Thermal-noise suppression in nano-scale Si field-effect transistors by feedback control based on single-electron detection

NASA Astrophysics Data System (ADS)

Chida, Kensaku; Nishiguchi, Katsuhiko; Yamahata, Gento; Tanaka, Hirotaka; Fujiwara, Akira

2015-08-01

We perform feedback (FB) control for suppressing thermal fluctuation in the number of electrons in a silicon single-electron (SE) device composed of a small transistor and capacitor. SEs enter and leave the capacitor via the transistor randomly at thermal equilibrium, which is monitored in real time using a high-charge-sensitivity detector. In order to suppress such random motion or thermal fluctuation of the electrons, SEs are injected and removed using the transistor according to the monitored change in the number of electrons in the capacitor, which is exactly the FB control. As a result, thermal fluctuation in the number of electrons in a SE device is suppressed by 60%, which corresponds to the so-called FB cooling from 300 to 110 K. Moreover, a thermodynamics analysis of this FB cooling reveals that entropy in the capacitor is reduced and the device is at non-equilibrium; i.e., the free energy of the device increases. Since this entropy reduction originates from information about the electrons' motion monitored by the detector, our results by the FB control represent one type of information-to-energy conversion.

Community Energy Storage Thermal Analysis and Management: Cooperative Research and Development Final Report, CRADA Number CRD-11-445

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, Kandler A.

The goal of this project is to create thermal solutions and models for community energy storage devices using both purpose-designed batteries and EV or PHEV batteries. Modeling will be employed to identify major factors of a device's lifetime and performance. Simultaneously, several devices will be characterized to determine their electrical and thermal performance under controlled conditions. After the factors are identified, a variety of thermal design approaches will be evaluated to improve the performance of energy storage devices. Upon completion of this project, recommendations for community energy storage device enclosures, thermal management systems, and/or battery sourcing will be made. NREL'smore » interest is in both new and aged batteries.« less

Embedded Thermal Control for Spacecraft Subsystems Miniaturization

NASA Technical Reports Server (NTRS)

Didion, Jeffrey R.

2014-01-01

Optimization of spacecraft size, weight and power (SWaP) resources is an explicit technical priority at Goddard Space Flight Center. Embedded Thermal Control Subsystems are a promising technology with many cross cutting NSAA, DoD and commercial applications: 1.) CubeSatSmallSat spacecraft architecture, 2.) high performance computing, 3.) On-board spacecraft electronics, 4.) Power electronics and RF arrays. The Embedded Thermal Control Subsystem technology development efforts focus on component, board and enclosure level devices that will ultimately include intelligent capabilities. The presentation will discuss electric, capillary and hybrid based hardware research and development efforts at Goddard Space Flight Center. The Embedded Thermal Control Subsystem development program consists of interrelated sub-initiatives, e.g., chip component level thermal control devices, self-sensing thermal management, advanced manufactured structures. This presentation includes technical status and progress on each of these investigations. Future sub-initiatives, technical milestones and program goals will be presented.

Rapid thermal processing by stamping

DOEpatents

Stradins, Pauls; Wang, Qi

2013-03-05

A rapid thermal processing device and methods are provided for thermal processing of samples such as semiconductor wafers. The device has components including a stamp (35) having a stamping surface and a heater or cooler (40) to bring it to a selected processing temperature, a sample holder (20) for holding a sample (10) in position for intimate contact with the stamping surface; and positioning components (25) for moving the stamping surface and the stamp (35) in and away from intimate, substantially non-pressured contact. Methods for using and making such devices are also provided. These devices and methods allow inexpensive, efficient, easily controllable thermal processing.

MEMS device for spacecraft thermal control applications

NASA Technical Reports Server (NTRS)

Swanson, Theordore D. (Inventor)

2003-01-01

A micro-electromechanical device that comprises miniaturized mechanical louvers, referred to as Micro Electro-Mechanical Systems (MEMS) louvers are employed to achieve a thermal control function for spacecraft and instruments. The MEMS louvers are another form of a variable emittance control coating and employ micro-electromechanical technology. In a function similar to traditional, macroscopic thermal louvers, the MEMS louvers of the present invention change the emissivity of a surface. With the MEMS louvers, as with the traditional macroscopic louvers, a mechanical vane or window is opened and closed to allow an alterable radiative view to space.

Micro-Scalable Thermal Control Device

NASA Technical Reports Server (NTRS)

Moran, Matthew E. (Inventor)

2002-01-01

A microscalable thermal control module consists of a Stirling cycle cooler that can be manipulated to operate at a selected temperature within the heating and cooling range of the module. The microscalable thermal control module is particularly suited for controlling the temperature of devices that must be maintained at precise temperatures. It is particularly suited for controlling the temperature of devices that need to be alternately heated or cooled. The module contains upper and lower opposing diaphragms, with a regenerator region containing a plurality of regenerators interposed between the diaphragms. Gaps exist on each side of each diaphragm to permit it to oscillate freely. The gap on the interior side one diaphragm is in fluid connection with the gap on the interior side of the other diaphragm through regenerators. As the diaphragms oscillate working gas is forced through the regenerators. The surface area of each regenerator is sufficiently large to effectively transfer thermal energy to and from the working gas as it is passed through them. The phase and amplitude of the oscillations can be manipulated electronically to control the steady state temperature of the active thermal control surface, and to switch the operation of the module from cooling to heating, or vice versa. The ability of the microscalable thermal control module to heat and cool may be enhanced by operating a plurality of modules in series, in parallel, or in connection through a shared bottom layer.

The effect of topical anesthetic hydration on the depth of thermal injury from the plasma skin regeneration device.

PubMed

Sanderson, Alicia R; Wu, Edward C; Liaw, Lih-Huei L; Garg, Rohit; Gangnes, Richard A

2014-02-01

The plasma skin regeneration (PSR) device delivers thermal energy to the skin by converting nitrogen gas to plasma. Prior to treatment, hydration of the skin is recommended as it is thought to limit the zone of thermal damage. However, there is limited data on optimal hydration time. This pilot study aims to determine the effect of topical anesthetic application time on the depth of thermal injury from a PSR device using histology. PSR (1.8 and 3.5 J) was performed after 0, 30, or 60 minutes of topical anesthetic application. Rhytidectomy was then performed and skin was fixed for histologic analysis. Four patients (two control and four treatment sites per patient) undergoing rhytidectomy were recruited for the study. Each patient served as his/her own control (no hydration). A scoring system for tissue injury was developed. Epidermal injury, the presence of vacuolization, blistering, damage to adnexal structures, and depth of dermal collagen changes were evaluated in over 1,400 high-power microscopy fields. There was a significant difference in the average thermal injury score, depth of thermal damage, and epidermal injury when comparing controls to 30 minutes of hydration (P = 0.012, 0.012, 0.017, respectively). There was no statistical difference between controls and 60 minutes of hydration or between 30 and 60 minutes of hydration. Epidermal vacuolization at low energy and patchy distribution of thermal injury was also observed. Topical hydration influences the amount of thermal damage when applied to skin for 30 minutes prior to treatment with the PSR device. There was a trend toward decreasing thermal damage at 60 minutes, and there was no difference between treatment for 30 or 60 minutes. The data suggest that application of topical anesthetic for a short period of time prior to treatment with the PSR device is cost-effective, safe, and may be clinically beneficial. © 2013 Wiley Periodicals, Inc.

Thermal-Responsive Polymers for Enhancing Safety of Electrochemical Storage Devices.

PubMed

Yang, Hui; Leow, Wan Ru; Chen, Xiaodong

2018-03-01

Thermal runway constitutes the most pressing safety issue in lithium-ion batteries and supercapacitors of large-scale and high-power density due to risks of fire or explosion. However, traditional strategies for averting thermal runaway do not enable the charging-discharging rate to change according to temperature or the original performance to resume when the device is cooled to room temperature. To efficiently control thermal runaway, thermal-responsive polymers provide a feasible and reversible strategy due to their ability to sense and subsequently act according to a predetermined sequence when triggered by heat. Herein, recent research progress on the use of thermal-responsive polymers to enhance the thermal safety of electrochemical storage devices is reviewed. First, a brief discussion is provided on the methods of preventing thermal runaway in electrochemical storage devices. Subsequently, a short review is provided on the different types of thermal-responsive polymers that can efficiently avoid thermal runaway, such as phase change polymers, polymers with sol-gel transitions, and polymers with positive temperature coefficients. The results represent the important development of thermal-responsive polymers toward the prevention of thermal runaway in next-generation smart electrochemical storage devices. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Millimeter-scale liquid metal droplet thermal switch

NASA Astrophysics Data System (ADS)

Yang, Tianyu; Kwon, Beomjin; Weisensee, Patricia B.; Kang, Jin Gu; Li, Xuejiao; Braun, Paul; Miljkovic, Nenad; King, William P.

2018-02-01

Devices capable of actively controlling heat flow have been desired by the thermal management community for decades. The need for thermal control has become particularly urgent with power densification resulting in devices with localized heat fluxes as high as 1 kW/cm2. Thermal switches, capable of modulating between high and low thermal conductances, enable the partitioning and active control of heat flow pathways. This paper reports a millimeter-scale thermal switch with a switching ratio >70, at heat fluxes near 10 W/cm2. The device consists of a silicone channel filled with a reducing liquid or vapor and an immersed liquid metal Galinstan slug. Galinstan has a relatively high thermal conductivity (≈16.5 W/mK at room temperature), and its position can be manipulated within the fluid channel, using either hydrostatic pressure or electric fields. When Galinstan bridges the hot and cold reservoirs (the "ON" state), heat flows across the channel. When the hot and cold reservoirs are instead filled with the encapsulating liquid or vapor (the "OFF" state), the cross-channel heat flow significantly reduces due to the lower thermal conductivity of the solution (≈0.03-0.6 W/mK). We demonstrate switching ratios as high as 15.6 for liquid filled channels and 71.3 for vapor filled channels. This work provides a framework for the development of millimeter-scale thermal switches and diodes capable of spatial and temporal control of heat flows.

21 CFR 870.5900 - Thermal regulating system.

Code of Federal Regulations, 2010 CFR

2010-04-01

... system. (a) Identification. A thermal regulating system is an external system consisting of a device that is placed in contact with the patient and a temperature controller for the device. The system is used to regulate patient temperature. (b) Classification. Class II (performance standards). ...

Phononic crystal devices

DOEpatents

El-Kady, Ihab F [Albuquerque, NM; Olsson, Roy H [Albuquerque, NM

2012-01-10

Phononic crystals that have the ability to modify and control the thermal black body phonon distribution and the phonon component of heat transport in a solid. In particular, the thermal conductivity and heat capacity can be modified by altering the phonon density of states in a phononic crystal. The present invention is directed to phononic crystal devices and materials such as radio frequency (RF) tags powered from ambient heat, dielectrics with extremely low thermal conductivity, thermoelectric materials with a higher ratio of electrical-to-thermal conductivity, materials with phononically engineered heat capacity, phononic crystal waveguides that enable accelerated cooling, and a variety of low temperature application devices.

Two dimensional thermal and charge mapping of power thyristors

NASA Technical Reports Server (NTRS)

Hu, S. P.; Rabinovici, B. M.

1975-01-01

The two dimensional static and dynamic current density distributions within the junction of semiconductor power switching devices and in particular the thyristors were obtained. A method for mapping the thermal profile of the device junctions with fine resolution using an infrared beam and measuring the attenuation through the device as a function of temperature were developed. The results obtained are useful in the design and quality control of high power semiconductor switching devices.

Variable Emittance Electrochromic Devices for Satellite Thermal Control

NASA Astrophysics Data System (ADS)

Demiryont, Hulya; Shannon, Kenneth C.

2007-01-01

An all-solid-state electrochromic device (ECD) was designed for electronic variable emissivity (VE) control. In this paper, a low weight (5g/m2) electrochromic thermal control device, the EclipseVEECD™, is detailed as a viable thermal control system for spacecraft outer surface temperatures. Discussion includes the technology's performance, satellite applications, and preparations for space based testing. This EclipseVEECD™ system comprises substrate/mirror electrode/active element/IR transparent electrode layers. This system tunes and modulates reflection/emittance from 5 μm to 15 μm region. Average reflectance/emittance modulation of the system from the 400 K to 250 K region is about 75%, while at room temperature (9.5 micron) reflectance/emittance is around 90%. Activation voltage of the EclipseVEECD™ is around ±1 Volt. The EclipseVEECD™ can be used as a smart thermal modulator for the thermal control of satellites and spacecraft by monitoring and adjusting the amount of energy emitted from the outer surfaces. The functionality of the EclipseVEECD™ was successfully demonstrated in vacuum using a multi-purpose heat dissipation/absorption test module, the EclipseHEAT™. The EclipseHEAT™ has been successfully flight checked and integrated onto the United States Naval Alchemy MidSTAR satellite, scheduled to launch December 2006.

Membrane Based Thermal Control Development

NASA Technical Reports Server (NTRS)

Murdoch, Karen

1997-01-01

The investigation of the feasibility of using a membrane device as a water boiler for thermal control is reported. The membrane device permits water vapor to escape to the vacuum of space but prevents the loss of liquid water. The vaporization of the water provides cooling to the water loop. This type of cooling device would have application for various types of short duration cooling needs where expenditure of water is allowed and a low pressure source is available such as in space or on a planet's surface. A variety of membrane samples, both hydrophilic and hydrophobic, were purchased to test for this thermal control application. An initial screening test determined if the membrane could pose a sufficient barrier to maintain water against vacuum. Further testing compared the heat transfer performance of those membranes that passed the screening test.

Cooling device featuring thermoelectric and diamond materials for temperature control of heat-dissipating devices

NASA Technical Reports Server (NTRS)

Vandersande, Ian W. (Inventor); Ewell, Richard (Inventor); Fleurial, Jean-Pierre (Inventor); Lyon, Hylan B. (Inventor)

1998-01-01

A cooling device for lowering the temperature of a heat-dissipating device. The cooling device includes a heat-conducting substrate (composed, e.g., of diamond or another high thermal conductivity material) disposed in thermal contact with the heat-dissipating device. During operation, heat flows from the heat-dissipating device into the heat-conducting substrate, where it is spread out over a relatively large area. A thermoelectric cooling material (e.g., a Bi.sub.2 Te.sub.3 -based film or other thermoelectric material) is placed in thermal contact with the heat-conducting substrate. Application of electrical power to the thermoelectric material drives the thermoelectric material to pump heat into a second heat-conducting substrate which, in turn, is attached to a heat sink.

Self-Protection of Electrochemical Storage Devices via a Thermal Reversible Sol-Gel Transition.

PubMed

Yang, Hui; Liu, Zhiyuan; Chandran, Bevita K; Deng, Jiyang; Yu, Jiancan; Qi, Dianpeng; Li, Wenlong; Tang, Yuxin; Zhang, Chenguang; Chen, Xiaodong

2015-10-07

Thermal self-protected intelligent electrochemical storage devices are fabricated using a reversible sol-gel transition of the electrolyte, which can decrease the specific capacitance and increase and enable temperature-dependent charging and discharging rates in the device. This work represents proof of a simple and useful concept, which shows tremendous promise for the safe and controlled power delivery in electrochemical devices. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Near-field thermal rectification devices using phase change periodic nanostructure.

PubMed

Ghanekar, Alok; Tian, Yanpei; Ricci, Matthew; Zhang, Sinong; Gregory, Otto; Zheng, Yi

2018-01-22

We theoretically analyze two near-field thermal rectification devices: a radiative thermal diode and a thermal transistor that utilize a phase change material to achieve dynamic control over heat flow by exploiting metal-insulator transition of VO 2 near 341 K. The thermal analogue of electronic diode allows high heat flow in one direction while it restricts the heat flow when the polarity of temperature gradient is reversed. We show that with the introduction of 1-D rectangular grating, thermal rectification is dramatically enhanced in the near-field due to reduced tunneling of surface waves across the interfaces for negative polarity. The radiative thermal transistor also works around phase transition temperature of VO 2 and controls heat flow. We demonstrate a transistor-like behavior wherein heat flow across the source and the drain can be greatly varied by making a small change in gate temperature.

Accelerated Aging System for Prognostics of Power Semiconductor Devices

NASA Technical Reports Server (NTRS)

Celaya, Jose R.; Vashchenko, Vladislav; Wysocki, Philip; Saha, Sankalita

2010-01-01

Prognostics is an engineering discipline that focuses on estimation of the health state of a component and the prediction of its remaining useful life (RUL) before failure. Health state estimation is based on actual conditions and it is fundamental for the prediction of RUL under anticipated future usage. Failure of electronic devices is of great concern as future aircraft will see an increase of electronics to drive and control safety-critical equipment throughout the aircraft. Therefore, development of prognostics solutions for electronics is of key importance. This paper presents an accelerated aging system for gate-controlled power transistors. This system allows for the understanding of the effects of failure mechanisms, and the identification of leading indicators of failure which are essential in the development of physics-based degradation models and RUL prediction. In particular, this system isolates electrical overstress from thermal overstress. Also, this system allows for a precise control of internal temperatures, enabling the exploration of intrinsic failure mechanisms not related to the device packaging. By controlling the temperature within safe operation levels of the device, accelerated aging is induced by electrical overstress only, avoiding the generation of thermal cycles. The temperature is controlled by active thermal-electric units. Several electrical and thermal signals are measured in-situ and recorded for further analysis in the identification of leading indicators of failures. This system, therefore, provides a unique capability in the exploration of different failure mechanisms and the identification of precursors of failure that can be used to provide a health management solution for electronic devices.

Modeling of endoluminal and interstitial ultrasound hyperthermia and thermal ablation: applications to device design, feedback control, and treatment planning

PubMed Central

Prakash, Punit; Salgaonkar, Vasant A.; Diederich, Chris J.

2014-01-01

Endoluminal and catheter-based ultrasound applicators are currently under development and are in clinical use for minimally invasive hyperthermia and thermal ablation of various tissue targets. Computational models play a critical role in in device design and optimization, assessment of therapeutic feasibility and safety, devising treatment monitoring and feedback control strategies, and performing patient-specific treatment planning with this technology. The critical aspects of theoretical modeling, applied specifically to endoluminal and interstitial ultrasound thermotherapy, are reviewed. Principles and practical techniques for modeling acoustic energy deposition, bioheat transfer, thermal tissue damage, and dynamic changes in the physical and physiological state of tissue are reviewed. The integration of these models and applications of simulation techniques in identification of device design parameters, development of real time feedback-control platforms, assessing the quality and safety of treatment delivery strategies, and optimization of inverse treatment plans are presented. PMID:23738697

Nuclear reactor safety device

DOEpatents

Hutter, Ernest

1986-01-01

A safety device is disclosed for use in a nuclear reactor for axially repositioning a control rod with respect to the reactor core in the event of an upward thermal excursion. Such safety device comprises a laminated helical ribbon configured as a tube-like helical coil having contiguous helical turns with slidably abutting edges. The helical coil is disclosed as a portion of a drive member connected axially to the control rod. The laminated ribbon is formed of outer and inner laminae. The material of the outer lamina has a greater thermal coefficient of expansion than the material of the inner lamina. In the event of an upward thermal excursion, the laminated helical coil curls inwardly to a smaller diameter. Such inward curling causes the total length of the helical coil to increase by a substantial increment, so that the control rod is axially repositioned by a corresponding amount to reduce the power output of the reactor.

Nuclear reactor safety device

DOEpatents

Hutter, E.

1983-08-15

A safety device is described for use in a nuclear reactor for axially repositioning a control rod with respect to the reactor core in the event of a thermal excursion. It comprises a laminated strip helically configured to form a tube, said tube being in operative relation to said control rod. The laminated strip is formed of at least two materials having different thermal coefficients of expansion, and is helically configured such that the material forming the outer lamina of the tube has a greater thermal coefficient of expansion than the material forming the inner lamina of said tube. In the event of a thermal excursion the laminated strip will tend to curl inwardly so that said tube will increase in length, whereby as said tube increases in length it exerts a force on said control rod to axially reposition said control rod with respect to said core.

40 CFR 63.361 - Definitions.

Code of Federal Regulations, 2013 CFR

2013-07-01

... oxidation control device or at the exhaust point from the combustion chamber of a thermal oxidation control... scrubber achieves at least 99-percent control of ethylene oxide emissions. Oxidation temperature means the temperature at the outlet point of a catalytic oxidation unit control device or at the exhaust point from the...

Observation of negative differential resistance in mesoscopic graphene oxide devices.

PubMed

Rathi, Servin; Lee, Inyeal; Kang, Moonshik; Lim, Dongsuk; Lee, Yoontae; Yamacli, Serhan; Joh, Han-Ik; Kim, Seongsu; Kim, Sang-Woo; Yun, Sun Jin; Choi, Sukwon; Kim, Gil-Ho

2018-05-08

The fractions of various functional groups in graphene oxide (GO) are directly related to its electrical and chemical properties and can be controlled by various reduction methods like thermal, chemical and optical. However, a method with sufficient controllability to regulate the reduction process has been missing. In this work, a hybrid method of thermal and joule heating processes is demonstrated where a progressive control of the ratio of various functional groups can be achieved in a localized area. With this precise control of carbon-oxygen ratio, negative differential resistance (NDR) is observed in the current-voltage characteristics of a two-terminal device in the ambient environment due to charge-activated electrochemical reactions at the GO surface. This experimental observation correlates with the optical and chemical characterizations. This NDR behavior offers new opportunities for the fabrication and application of such novel electronic devices in a wide range of devices applications including switches and oscillators.

A thermal control system for long-term survival of scientific instruments on lunar surface.

PubMed

Ogawa, K; Iijima, Y; Sakatani, N; Otake, H; Tanaka, S

2014-03-01

A thermal control system is being developed for scientific instruments placed on the lunar surface. This thermal control system, Lunar Mission Survival Module (MSM), was designed for scientific instruments that are planned to be operated for over a year in the future Japanese lunar landing mission SELENE-2. For the long-term operations, the lunar surface is a severe environment because the soil (regolith) temperature varies widely from nighttime -200 degC to daytime 100 degC approximately in which space electronics can hardly survive. The MSM has a tent of multi-layered insulators and performs a "regolith mound". Temperature of internal devices is less variable just like in the lunar underground layers. The insulators retain heat in the regolith soil in the daylight, and it can keep the device warm in the night. We conducted the concept design of the lunar survival module, and estimated its potential by a thermal mathematical model on the assumption of using a lunar seismometer designed for SELENE-2. Thermal vacuum tests were also conducted by using a thermal evaluation model in order to estimate the validity of some thermal parameters assumed in the computed thermal model. The numerical and experimental results indicated a sufficient survivability potential of the concept of our thermal control system.

Controlling Synergistic Oxidation Processes for Efficient and Stable Blue Thermally Activated Delayed Fluorescence Devices.

PubMed

Cui, Lin-Song; Deng, Ya-Li; Tsang, Daniel Ping-Kuen; Jiang, Zuo-Quan; Zhang, Qisheng; Liao, Liang-Sheng; Adachi, Chihaya

2016-09-01

Efficient sky-blue organic light-emitting diodes (OLEDs) employing thermally activated delayed fluorescence (TADF) display a three orders of magnitude increase in lifetime, which is superior to those of controlled phosphorescent OLEDs used in this study. The combination of electro-oxidation and photo-oxidation of the TADF emitters in their triplet excited-states is suppressed through molecule design and device engineering. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Dynamic Angular Control Of Thermal Therapy With Stationary Multi-Sectored Tubular Ultrasound Applicators Under MR Temperature Monitoring

NASA Astrophysics Data System (ADS)

Kinsey, Adam M.; Diederich, Chris J.; Nau, William H.; Ross, Anthony B.; Butts Pauly, Kim; Rieke, Viola; Sommer, Graham

2006-05-01

Multi-sectored ultrasound heating applicators with dynamic angular and longitudinal control of heating profiles are being investigated for the thermal treatment of tumors in sites such as prostate, uterus, and brain. Multi-sectored tubular ultrasound transducers with independent sector power control were incorporated into interstitial and transurethral applicators and provided dynamic angular control of a heating pattern without requiring device manipulation during treatment. Acoustic beam measurements of each applicator type demonstrated a 35-40° acoustic dead zone between each independent sector, with negligible mechanical or electrical coupling. Despite the acoustic dead zone between sectors, simulations and experiments under MR temperature (MRT) monitoring showed that the variance from the maximum lesion radius (scalloping) with all elements activated on a transducer was minimal and did not affect conformal heating of a target area. A biothermal model with a multi-point controller was used to adjust the applied power and treatment time of individual transducer segments as the tissue temperature changed in simulations of thermal lesions with both interstitial and transurethral applicators. Transurethral ultrasound applicators for benign prostatic hyperplasia (BPH) treatment with either three or four sectors conformed a thermal dose to a simulated target area in the angular and radial dimensions. The simulated treatment was controlled to a maximum temperature of 85°C, and had a maximum duration of 5 min when power was turned off as the 52°C temperature contour reach a predetermined control point for each sector in the tissue. Experiments conducted with multi-sectored applicators under MRT monitoring showed thermal ablation and hyperthermia treatments had little or no border `scalloping', conformed to a pretreatment target area, and correlated very well with the simulated thermal lesions. The radial penetration of the heat treatments in tissue with interstitial (1.5-1.8 mm OD transducer) and transurethral (2.5-4.0 mm OD transducer) applicators was at least 1.5 cm and 2.0 cm, respectively, for a treatment duration of 10 min. Angular control of thermal ablation and hyperthermia therapy often relies upon non-adjustable angular power deposition patterns and/or mechanical manipulation of the heating device. The multi-sectored ultrasound applicators developed in this study provide dynamic control of the angular heating distribution during treatment without device manipulation and maintain previously reported heating penetration and spatial control characteristics of similar ultrasound devices.

Thermal research of infrared sight thermoelectric cooler control circuit under temperature environment

NASA Astrophysics Data System (ADS)

Gao, Youtang; Ding, Huan; Xue, Xiao; Xu, Yuan; Chang, Benkang

2010-10-01

Testing device TST-05B, which is suitable for adaptability test of semiconductor devices, electronic products and other military equipment under the condition of the surrounding air temperature rapidly changing, is used here for temperature shock test.Thermal stability technology of thermoelectric cooler control circuit infrared sight under temperature shock is studied in this paper. Model parameters and geometry is configured for ADI devices (ADN8830), welding material and PCB which are used in system. Thermoelectric cooler control circuit packaged by CSP32 distribution are simulated and analyzed by thermal shock and waveform through engineering finite element analysis software ANSYYS. Because solders of the whole model have much stronger stress along X direction than that of other directions, initial stress constraints along X direction are primarily considered when the partial model of single solder is imposed by thermal load. When absolute thermal loads stresses of diagonal nodes with maximum strains are separated from the whole model, interpolation is processed according to thermal loads circulation. Plastic strains and thermal stresses of nodes in both sides of partial model are obtained. The analysis results indicates that with thermal load circulation, maximum forces of each circulation along X direction are increasingly enlarged and with the accumulation of plastic strains of danger point, at the same time structural deformation and the location of maximum equivalent plastic strain in the solder joints at the first and eighth, the composition will become invalid in the end.

40 CFR 63.3981 - What definitions apply to this subpart?

Code of Federal Regulations, 2011 CFR

2011-07-01

..., activators, accelerators). Add-on control means an air pollution control device, such as a thermal oxidizer or carbon adsorber, that reduces pollution in an air stream by destruction or removal before... directing those emissions into an add-on air pollution control device. Capture efficiency or capture system...

Integrated microelectrode array and microfluidics for temperature clamp of sensory neurons in culture.

PubMed

Pearce, Thomas M; Wilson, J Adam; Oakes, S George; Chiu, Shing-Yan; Williams, Justin C

2005-01-01

A device for cell culture is presented that combines MEMS technology and liquid-phase photolithography to create a microfluidic chip that influences and records electrical cellular activity. A photopolymer channel network is formed on top of a multichannel microelectrode array. Preliminary results indicated successful local thermal control within microfluidic channels and control of lamina position over the electrode array. To demonstrate the biological application of such a device, adult dissociated dorsal root ganglion neurons with a subpopulation of thermally-sensitive cells are attached onto the electrode array. Using laminar flow, dynamic control of local temperature of the neural cells was achieved while maintaining a constant chemical culture medium. Recording the expected altered cellular activity confirms the success of the integrated device.

Methods of measurement for semiconductor materials, process control, and devices

NASA Technical Reports Server (NTRS)

Bullis, W. M. (Editor)

1971-01-01

The development of methods of measurement for semiconductor materials, process control, and devices is discussed. The following subjects are also presented: (1) demonstration of the high sensitivity of the infrared response technique by the identification of gold in a germanium diode, (2) verification that transient thermal response is significantly more sensitive to the presence of voids in die attachment than steady-state thermal resistance, and (3) development of equipment for determining susceptibility of transistors to hot spot formation by the current-gain technique.

Thermal contact conductance as a method of rectification in bulk materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sayer, Robert A.

2016-08-01

A thermal rectifier that utilizes thermal expansion to directionally control interfacial conductance between two contacting surfaces is presented. The device consists of two thermal reservoirs contacting a beam with one rough and one smooth end. When the temperature of reservoir in contact with the smooth surface is raised, a similar temperature rise will occur in the beam, causing it to expand, thus increasing the contact pressure at the rough interface and reducing the interfacial contact resistance. However, if the temperature of the reservoir in contact with the rough interface is raised, the large contact resistance will prevent a similar temperaturemore » rise in the beam. As a result, the contact pressure will be marginally affected and the contact resistance will not change appreciably. Owing to the decreased contact resistance of the first scenario compared to the second, thermal rectification occurs. A parametric analysis is used to determine optimal device parameters including surface roughness, contact pressure, and device length. Modeling predicts that rectification factors greater than 2 are possible at thermal biases as small as 3 K. Lastly, thin surface coatings are discussed as a method to control the temperature bias at which maximum rectification occurs.« less

Optically Immersed Bolometer IR Detectors Based on V2O5 Thin Films with Polyimide Thermal Impedance Control Layer for Space Applications

NASA Astrophysics Data System (ADS)

Sumesh, M. A.; Thomas, Beno; Vijesh, T. V.; Mohan Rao, G.; Viswanathan, M.; Karanth, S. P.

2018-01-01

Optically immersed bolometer IR detectors were fabricated using electron beam evaporated vanadium oxide as the sensing material. Spin-coated polyimide was used as medium to optically immerse the sensing element to the flat surface of a hemispherical germanium lens. This optical immersion layer also serves as the thermal impedance control layer and decides the performance of the devices in terms of responsivity and noise parameters. The devices were packaged in suitable electro-optical packages and the detector parameters were studied in detail. Thermal time constant varies from 0.57 to 6.0 ms and responsivity from 75 to 757 V W-1 corresponding to polyimide thickness in the range 2 to 70 μm for a detector bias of 9 V in the wavelength region of 14-16 μm. Highest D* obtained was 1.2×108 cmHz1/2 W-1. Noise equivalent temperature difference (NETD) of 20 mK was achieved for devices with polyimide thickness more than 32 μm. The figure of merit, NETD × τ product which describes trade-off between thermal time constant and sensitivity is also extensively studied for devices having different thickness of thermal impedance layers.

Controllable Growth of Perovskite Films by Room-Temperature Air Exposure for Efficient Planar Heterojunction Photovoltaic Cells

DOE PAGES

Yang, Bin; Dyck, Ondrej; Poplawsky, Jonathan; ...

2015-12-01

A two-step-solution-processing approach has been established to grow void-free perovskite films for low-cost and high-performance planar heterojunction photovoltaic devices. We generally applied a high-temperature thermal annealing treatment in order to drive the diffusion of CH 3NH 3I precursor molecules into the compact PbI 2 layer to form perovskite films. But, thermal annealing for extended periods would lead to degraded device performance due to the defects generated by decomposition of perovskite into PbI 2. In this work, we explored a controllable layer-by-layer spin-coating method to grow bilayer CH 3NH 3I/PbI 2 films, and then drive the interdiffusion between PbI 2 andmore » CH 3NH 3I layers by a simple room-temperature-air-exposure for making well-oriented, highly-crystalline perovskite films without thermal annealing. This high degree of crystallinity resulted in a carrier diffusion length of ~ 800 nm and high device efficiency of 15.6%, which is comparable to the reported values from thermally-annealed perovskite films based counterparts. Finally, the simplicity and high device performance of this processing approach is highly promising for direct integration into industrial-scale device manufacture.« less

Simulation of a steady-state integrated human thermal system.

NASA Technical Reports Server (NTRS)

Hsu, F. T.; Fan, L. T.; Hwang, C. L.

1972-01-01

The mathematical model of an integrated human thermal system is formulated. The system consists of an external thermal regulation device on the human body. The purpose of the device (a network of cooling tubes held in contact with the surface of the skin) is to maintain the human body in a state of thermoneutrality. The device is controlled by varying the inlet coolant temperature and coolant mass flow rate. The differential equations of the model are approximated by a set of algebraic equations which result from the application of the explicit forward finite difference method to the differential equations. The integrated human thermal system is simulated for a variety of combinations of the inlet coolant temperature, coolant mass flow rate, and metabolic rates.

A thermal control system for long-term survival of scientific instruments on lunar surface

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ogawa, K., E-mail: ogawa@astrobio.k.u-tokyo.ac.jp; Iijima, Y.; Tanaka, S.

2014-03-15

A thermal control system is being developed for scientific instruments placed on the lunar surface. This thermal control system, Lunar Mission Survival Module (MSM), was designed for scientific instruments that are planned to be operated for over a year in the future Japanese lunar landing mission SELENE-2. For the long-term operations, the lunar surface is a severe environment because the soil (regolith) temperature varies widely from nighttime −200 degC to daytime 100 degC approximately in which space electronics can hardly survive. The MSM has a tent of multi-layered insulators and performs a “regolith mound”. Temperature of internal devices is lessmore » variable just like in the lunar underground layers. The insulators retain heat in the regolith soil in the daylight, and it can keep the device warm in the night. We conducted the concept design of the lunar survival module, and estimated its potential by a thermal mathematical model on the assumption of using a lunar seismometer designed for SELENE-2. Thermal vacuum tests were also conducted by using a thermal evaluation model in order to estimate the validity of some thermal parameters assumed in the computed thermal model. The numerical and experimental results indicated a sufficient survivability potential of the concept of our thermal control system.« less

Promising and Reversible Electrolyte with Thermal Switching Behavior for Safer Electrochemical Storage Devices.

PubMed

Shi, Yunhui; Zhang, Qian; Zhang, Yan; Jia, Limin; Xu, Xinhua

2018-02-28

A major stumbling block in large-scale adoption of high-energy-density electrochemical devices has been safety issues. Methods to control thermal runaway are limited by providing a one-time thermal protection. Herein, we developed a simple and reversible thermoresponsive electrolyte system that is efficient to shutdown the current flow according to temperature changes. The thermal management is ascribed to the thermally activated sol-gel transition of methyl cellulose solution, associated with the concentration of ions that can move between isolated chains freely or be restricted by entangled molecular chains. We studied the effect of cellulose concentration, substituent types, and operating temperature on the electrochemical performance, demonstrating an obvious capacity loss up to 90% approximately of its initial value. Moreover, this is a cost-effective approach that has the potential for use in practical electrochemical storage devices.

Variable Emissivity Through MEMS Technology

NASA Technical Reports Server (NTRS)

Darrin, Ann Garrison; Osiander, Robert; Champion, John; Swanson, Ted; Douglas, Donya; Grob, Lisa M.; Powers, Edward I. (Technical Monitor)

2000-01-01

This paper discusses a new technology for variable emissivity (vari-e) radiator surfaces, which has significant advantages over traditional radiators and promises an alternative design technique for future spacecraft thermal control systems. All spacecraft rely on radiative surfaces to dissipate waste heat. These radiators have special coatings, typically with a low solar absorptivity and a high infrared-red emissivity, that are intended to optimize performance under the expected heat load and thermal sink environment. The dynamics of the heat loads and thermal environment make it a challenge to properly size the radiator and often require some means of regulating the heat rejection rate of the radiators in order to achieve proper thermal balance. Specialized thermal control coatings, which can passively or actively adjust their emissivity offer an attractive solution to these design challenges. Such systems would allow intelligent control of the rate of heat loss from a radiator in response to heat load and thermal environmental variations. Intelligent thermal control through variable emissivity systems is well suited for nano and pico spacecraft applications where large thermal fluctuations are expected due to the small thermal mass and limited electric resources. Presently there are three different types of vari-e technologies under development: Micro ElectroMechanical Systems (MEMS) louvers, Electrochromic devices, and Electrophoretic devices. This paper will describe several prototypes of micromachined (MEMS) louvers and experimental results for the emissivity variations measured on theses prototypes. It will further discuss possible actuation mechanisms and space reliability aspects for different designs. Finally, for comparison parametric evaluations of the thermal performances of the new vari-e technology and standard thermal control systems are presented in this paper.

Impact of Reflow on the Output Characteristics of Piezoelectric Microelectromechanical System Devices

NASA Astrophysics Data System (ADS)

Nogami, Hirofumi; Kobayashi, Takeshi; Okada, Hironao; Masuda, Takashi; Maeda, Ryutaro; Itoh, Toshihiro

2012-09-01

An animal health monitoring system and a wireless sensor node aimed at preventing the spread of animal-transmitted diseases and improving pastoral efficiency which are especially suitable for chickens, were developed. The sensor node uses a piezoelectric microelectromechanical system (MEMS) device and an event-driven system that is activated by the movements of a chicken. The piezoelectric MEMS device has two functions: a) it measures the activity of a chicken and b) switches the micro-control unit (MCU) of the wireless sensor node from the sleep mode. The piezoelectric MEMS device is required to produce high output voltages when the chicken moves. However, after the piezoelectric MEMS device was reflowed to the wireless sensor node, the output voltages of the piezoelectric MEMS device decreased. The main reason for this might be the loss of residual polarization, which is affected by the thermal load during the reflow process. After the reflow process, we were not able to apply a voltage to the piezoelectric MEMS device; thus, the piezoelectric output voltage was not increased by repoling the piezoelectric MEMS device. To address the thermal load of the reflow process, we established a thermal poling treatment, which achieves a higher temperature than the reflow process. We found that on increasing the thermal poling temperature, the piezoelectric output voltages did not decreased low significantly. Thus, we considered that a thermal poling temperature higher than that of the reflow process prevents the piezoelectric output voltage reduction caused by the thermal load.

Thermal Switch for Satellite Temperature Control

NASA Technical Reports Server (NTRS)

Ziad, H.; Slater, T.; vanGerwen, P.; Masure, E.; Preudhomme, F.; Baert, K.

1995-01-01

An active radiator tile (ART) thermal valve has been fabricated using silicon micromachining. Intended for orbital satellite heat control applications, the operational principal of the ART is to control heat flow between two thermally isolated surfaces by bring the surfaces into intimate mechanical contact using electrostatic actuation. Prototype devices have been tested in a vacuum and demonstrate thermal actuation voltages as low as 40 volts, very good thermal insulation in the OFF state, and a large increase in radiative heat flow in the ON state. Thin, anodized aluminum was developed as a coating for high infrared emissivity and high solar reflectance.

40 CFR 63.4981 - What definitions apply to this subpart?

Code of Federal Regulations, 2013 CFR

2013-07-01

... subpart are defined in the CAA, in 40 CFR 63.2, and in this section as follows: Add-on control means an air pollution control device such as a thermal oxidizer or carbon adsorber that reduces pollution in... those emissions into an add-on air pollution control device. Capture efficiency or capture system...

40 CFR 63.4981 - What definitions apply to this subpart?

Code of Federal Regulations, 2012 CFR

2012-07-01

... subpart are defined in the CAA, in 40 CFR 63.2, and in this section as follows: Add-on control means an air pollution control device such as a thermal oxidizer or carbon adsorber that reduces pollution in... those emissions into an add-on air pollution control device. Capture efficiency or capture system...

40 CFR 63.4981 - What definitions apply to this subpart?

Code of Federal Regulations, 2014 CFR

2014-07-01

... subpart are defined in the CAA, in 40 CFR 63.2, and in this section as follows: Add-on control means an air pollution control device such as a thermal oxidizer or carbon adsorber that reduces pollution in... those emissions into an add-on air pollution control device. Capture efficiency or capture system...

Transient experimental demonstration of an elliptical thermal camouflage device.

PubMed

He, Xiao; Yang, Tianzhi; Zhang, Xingwei; Wu, Linzhi; He, Xiao Qiao

2017-11-30

The camouflage phenomenon (invisibility or illusion) of thermodynamics has attracted great attentions and many experimental demonstrations have been achieved by virtue of simplified approaches or the scattering cancellation. However, all of the experiments conducted are limited in the invisibility of spheres or two-dimensional (2D) cylinders. An ellipsoid camouflage device with a homogenous and isotropic shell is firstly reported based on the idea of the neutral inclusion and a 2D elliptical thermal camouflage device is realized by a thin-layer cloak of homogeneous isotropic material firstly. The robustness of this scheme is validated in both 2D and 3D configurations. The current work may provide a new avenue to the control of the thermal signatures and we believe this work will broaden the current research and pave a new path to the control of the path of the heat transfer.

Thermal modeling of phase change solidification in thermal control devices including natural convection effects

NASA Technical Reports Server (NTRS)

Ukanwa, A. O.; Stermole, F. J.; Golden, J. O.

1972-01-01

Natural convection effects in phase change thermal control devices were studied. A mathematical model was developed to evaluate natural convection effects in a phase change test cell undergoing solidification. Although natural convection effects are minimized in flight spacecraft, all phase change devices are ground tested. The mathematical approach to the problem was to first develop a transient two-dimensional conduction heat transfer model for the solidification of a normal paraffin of finite geometry. Next, a transient two-dimensional model was developed for the solidification of the same paraffin by a combined conduction-natural-convection heat transfer model. Throughout the study, n-hexadecane (n-C16H34) was used as the phase-change material in both the theoretical and the experimental work. The models were based on the transient two-dimensional finite difference solutions of the energy, continuity, and momentum equations.

Influence of intrinsic noise generated by a thermotesting device on thermal sensory detection and thermal pain detection thresholds.

PubMed

Pavlaković, G; Züchner, K; Zapf, A; Bachmann, C G; Graf, B M; Crozier, T A; Pavlaković, H

2009-08-01

Various factors can influence thermal perception threshold measurements and contribute significantly to unwanted variability of the tests. To minimize this variability, testing should be performed under strictly controlled conditions. Identifying the factors that increase the variability and eliminating their influence should increase reliability and reproducibility. Currently available thermotesting devices use a water-cooling system that generates a continuous noise of approximately 60 dB. In order to analyze whether this noise could influence the thermal threshold measurements we compared the thresholds obtained with a silent thermotesting device to those obtained with a commercially available device. The subjects were tested with one randomly chosen device on 1 day and with the other device 7 days later. At each session, heat, heat pain, cold, and cold pain thresholds were determined with three measurements. Bland-Altman analysis was used to assess agreement in measurements obtained with different devices and it was shown that the intersubject variability of the thresholds obtained with the two devices was comparable for all four thresholds tested. In contrast, the intrasubject variability of the thresholds for heat, heat pain, and cold pain detection was significantly lower with the silent device. Our results show that thermal sensory thresholds measured with the two devices are comparable. However, our data suggest that, for studies with repeated measurements on the same subjects, a silent thermotesting device may allow detection of smaller differences in the treatment effects and/or may permit the use of a smaller number of tested subjects. Muscle Nerve 40: 257-263, 2009.

Design of a handheld infrared imaging device based on uncooled infrared detector

NASA Astrophysics Data System (ADS)

Sun, Xianzhong; Li, Junwei; Zhang, Yazhou

2017-02-01

This paper, we introduced the system structure and operation principle of the device, and discussed our solutions for image data acquisition and storage, operating states and modes control and power management in detail. Besides, we proposed a algorithm of pseudo color for thermal image and applied it to the image processing module of the device. The thermal images can be real time displayed in a 1.8 inches TFT-LCD. The device has a compacted structure and can be held easily by one hand. It also has a good imaging performance with low power consumption, thermal sensitivity is less than 150mK. At last, we introduced one of its applications for fault diagnosis in electronic circuits, the test shows that: it's a good solution for fast fault detection.

Thermal conductivity and thermal boundary resistance of atomic layer deposited high-k dielectric aluminum oxide, hafnium oxide, and titanium oxide thin films on silicon

NASA Astrophysics Data System (ADS)

Scott, Ethan A.; Gaskins, John T.; King, Sean W.; Hopkins, Patrick E.

2018-05-01

The need for increased control of layer thickness and uniformity as device dimensions shrink has spurred increased use of atomic layer deposition (ALD) for thin film growth. The ability to deposit high dielectric constant (high-k) films via ALD has allowed for their widespread use in a swath of optical, optoelectronic, and electronic devices, including integration into CMOS compatible platforms. As the thickness of these dielectric layers is reduced, the interfacial thermal resistance can dictate the overall thermal resistance of the material stack compared to the resistance due to the finite dielectric layer thickness. Time domain thermoreflectance is used to interrogate both the thermal conductivity and the thermal boundary resistance of aluminum oxide, hafnium oxide, and titanium oxide films on silicon. We calculate a representative design map of effective thermal resistances, including those of the dielectric layers and boundary resistances, as a function of dielectric layer thickness, which will be of great importance in predicting the thermal resistances of current and future devices.

40 CFR 63.4981 - What definitions apply to this subpart?

Code of Federal Regulations, 2011 CFR

2011-07-01

... defined in the CAA, in 40 CFR 63.2, and in this section as follows: Add-on control means an air pollution control device such as a thermal oxidizer or carbon adsorber that reduces pollution in an air stream by... add-on air pollution control device. Capture efficiency or capture system efficiency means the portion...

Development of a prototype two-phase thermal bus system for Space Station

NASA Technical Reports Server (NTRS)

Myron, D. L.; Parish, R. C.

1987-01-01

This paper describes the basic elements of a pumped two-phase ammonia thermal control system designed for microgravity environments, the development of the concept into a Space Station flight design, and design details of the prototype to be ground-tested in the Johnson Space Center (JSC) Thermal Test Bed. The basic system concept is one of forced-flow heat transport through interface heat exchangers with anhydrous ammonia being pumped by a device expressly designed for two-phase fluid management in reduced gravity. Control of saturation conditions, and thus system interface temperatures, is accomplished with a single central pressure regulating valve. Flow control and liquid inventory are controlled by passive, nonelectromechanical devices. Use of these simple control elements results in minimal computer controls and high system reliability. Building on the basic system concept, a brief overview of a potential Space Station flight design is given. Primary verification of the system concept will involve testing at JSC of a 25-kW ground test article currently in fabrication.

ISOTOPE CONVERSION DEVICE

DOEpatents

Wigner, E.P.; Young, G.J.; Ohlinger, L.A.

1957-12-01

This patent relates to nuclear reactors of tbe type utilizing a liquid fuel and designed to convert a non-thermally fissionable isotope to a thermally fissionable isotope by neutron absorption. A tank containing a reactive composition of a thermally fissionable isotope dispersed in a liquid moderator is disposed within an outer tank containing a slurry of a non-thermally fissionable isotope convertible to a thermally fissionable isotope by neutron absorption. A control rod is used to control the chain reaction in the reactive composition and means are provided for circulating and cooling the reactive composition and slurry in separate circuits.

Silk-based resorbable electronic devices for remotely controlled therapy and in vivo infection abatement

PubMed Central

Tao, Hu; Hwang, Suk-Won; Marelli, Benedetto; An, Bo; Moreau, Jodie E.; Yang, Miaomiao; Brenckle, Mark A.; Kim, Stanley; Kaplan, David L.; Rogers, John A.; Omenetto, Fiorenzo G.

2014-01-01

A paradigm shift for implantable medical devices lies at the confluence between regenerative medicine, where materials remodel and integrate in the biological milieu, and technology, through the use of recently developed material platforms based on biomaterials and bioresorbable technologies such as optics and electronics. The union of materials and technology in this context enables a class of biomedical devices that can be optically or electronically functional and yet harmlessly degrade once their use is complete. We present here a fully degradable, remotely controlled, implantable therapeutic device operating in vivo to counter a Staphylococcus aureus infection that disappears once its function is complete. This class of device provides fully resorbable packaging and electronics that can be turned on remotely, after implantation, to provide the necessary thermal therapy or trigger drug delivery. Such externally controllable, resorbable devices not only obviate the need for secondary surgeries and retrieval, but also have extended utility as therapeutic devices that can be left behind at a surgical or suturing site, following intervention, and can be externally controlled to allow for infection management by either thermal treatment or by remote triggering of drug release when there is retardation of antibiotic diffusion, deep infections are present, or when systemic antibiotic treatment alone is insufficient due to the emergence of antibiotic-resistant strains. After completion of function, the device is safely resorbed into the body, within a programmable period. PMID:25422476

Silk-based resorbable electronic devices for remotely controlled therapy and in vivo infection abatement.

PubMed

Tao, Hu; Hwang, Suk-Won; Marelli, Benedetto; An, Bo; Moreau, Jodie E; Yang, Miaomiao; Brenckle, Mark A; Kim, Stanley; Kaplan, David L; Rogers, John A; Omenetto, Fiorenzo G

2014-12-09

A paradigm shift for implantable medical devices lies at the confluence between regenerative medicine, where materials remodel and integrate in the biological milieu, and technology, through the use of recently developed material platforms based on biomaterials and bioresorbable technologies such as optics and electronics. The union of materials and technology in this context enables a class of biomedical devices that can be optically or electronically functional and yet harmlessly degrade once their use is complete. We present here a fully degradable, remotely controlled, implantable therapeutic device operating in vivo to counter a Staphylococcus aureus infection that disappears once its function is complete. This class of device provides fully resorbable packaging and electronics that can be turned on remotely, after implantation, to provide the necessary thermal therapy or trigger drug delivery. Such externally controllable, resorbable devices not only obviate the need for secondary surgeries and retrieval, but also have extended utility as therapeutic devices that can be left behind at a surgical or suturing site, following intervention, and can be externally controlled to allow for infection management by either thermal treatment or by remote triggering of drug release when there is retardation of antibiotic diffusion, deep infections are present, or when systemic antibiotic treatment alone is insufficient due to the emergence of antibiotic-resistant strains. After completion of function, the device is safely resorbed into the body, within a programmable period.

Precision Control of Thermal Transport in Cryogenic Single-Crystal Silicon Devices

NASA Technical Reports Server (NTRS)

Rostem, K.; Chuss, D. T.; Colazo, F. A.; Crowe, E. J.; Denis, K. L.; Lourie, N. P.; Moseley, S. H.; Stevenson, T. R.; Wollack, E. J.

2014-01-01

We report on the diffusive-ballistic thermal conductance of multi-moded single-crystal silicon beams measured below 1 K. It is shown that the phonon mean-free-path is a strong function of the surface roughness characteristics of the beams. This effect is enhanced in diffuse beams with lengths much larger than, even when the surface is fairly smooth, 510 nm rms, and the peak thermal wavelength is 0.6 microns. Resonant phonon scattering has been observed in beams with a pitted surface morphology and characteristic pit depth of 30 nm. Hence, if the surface roughness is not adequately controlled, the thermal conductance can vary significantly for diffuse beams fabricated across a wafer. In contrast, when the beam length is of order, the conductance is dominated by ballistic transport and is effectively set by the beam cross-sectional area. We have demonstrated a uniformity of +/-8% in fractional deviation for ballistic beams, and this deviation is largely set by the thermal conductance of diffuse beams that support the micro-electro-mechanical device and electrical leads. In addition, we have found no evidence for excess specific heat in single-crystal silicon membranes. This allows for the precise control of the device heat capacity with normal metal films. We discuss the results in the context of the design and fabrication of large-format arrays of far-infrared and millimeter wavelength cryogenic detectors.

Controllable Growth of Perovskite Films by Room-Temperature Air Exposure for Efficient Planar Heterojunction Photovoltaic Cells.

PubMed

Yang, Bin; Dyck, Ondrej; Poplawsky, Jonathan; Keum, Jong; Das, Sanjib; Puretzky, Alexander; Aytug, Tolga; Joshi, Pooran C; Rouleau, Christopher M; Duscher, Gerd; Geohegan, David B; Xiao, Kai

2015-12-01

A two-step solution processing approach has been established to grow void-free perovskite films for low-cost high-performance planar heterojunction photovoltaic devices. A high-temperature thermal annealing treatment was applied to drive the diffusion of CH3NH3I precursor molecules into a compact PbI2 layer to form perovskite films. However, thermal annealing for extended periods led to degraded device performance owing to the defects generated by decomposition of perovskite into PbI2. A controllable layer-by-layer spin-coating method was used to grow "bilayer" CH3NH3I/PbI2 films, and then drive the interdiffusion between PbI2 and CH3NH3I layers by a simple air exposure at room temperature for making well-oriented, highly crystalline perovskite films without thermal annealing. This high degree of crystallinity resulted in a carrier diffusion length of ca. 800 nm and a high device efficiency of 15.6%, which is comparable to values reported for thermally annealed perovskite films. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Energy management system for a rotary machine and method therefor

DOEpatents

Bowman, Michael John; Sinha, Gautam; Sheldon, Karl Edward

2004-11-09

In energy management system is provided for a power generating device having a working fluid intake in which the energy management system comprises an electrical dissipation device coupled to the power generating device and a dissipation device cooling system configured to direct a portion of a working fluid to the electrical dissipation device so as to provide thermal control to the electrical dissipation device.

Invisibility problem in acoustics, electromagnetism and heat transfer. Inverse design method

NASA Astrophysics Data System (ADS)

Alekseev, G.; Tokhtina, A.; Soboleva, O.

2017-10-01

Two approaches (direct design and inverse design methods) for solving problems of designing devices providing invisibility of material bodies of detection using different physical fields - electromagnetic, acoustic and static are discussed. The second method is applied for solving problems of designing cloaking devices for the 3D stationary thermal scattering model. Based on this method the design problems under study are reduced to respective control problems. The material parameters (radial and tangential heat conductivities) of the inhomogeneous anisotropic medium filling the thermal cloak and the density of auxiliary heat sources play the role of controls. A unique solvability of direct thermal scattering problem in the Sobolev space is proved and the new estimates of solutions are established. Using these results, the solvability of control problem is proved and the optimality system is derived. Based on analysis of optimality system, the stability estimates of optimal solutions are established and numerical algorithms for solving particular thermal cloaking problem are proposed.

Thermoelectrically controlled device for studies of temperature-induced corneal shrinkage

NASA Astrophysics Data System (ADS)

Borja, David; Manns, Fabrice; Fernandez, Viviana; Lamar, Peggy; Soederberg, Per G.; Parel, Jean-Marie A.

2002-06-01

The purpose of this study was to design and calibrate a device to measure the dynamics of thermal shrinkage in corneal and scleral strips. The apparatus consists of a thermoelectric cell controlled by a temperature controller designed to generate temperatures up to 90 degree(s)C in rectangular corneal strips; a copper cuvette filled with Dextran solution that holds the corneal strip and a displacement sensor that measures the change in length of the tissue during heat-induced shrinkage. The device was tested on corneal tissue from Florida Eye-Bank eyes that were cut into 2x4mm rectangular strips. Preliminary results indicate that our system can reproducibly create and accurately measure thermally induced corneal shrinkage. Shrinkage experiments will be used to optimize laser parameters for corneal shrinkage during laser thermokeratoplasty and laser scleral buckling.

Semiconductor technology program. Progress briefs

NASA Technical Reports Server (NTRS)

Bullis, W. M.

1980-01-01

Measurement technology for semiconductor materials, process control, and devices is reviewed. Activities include: optical linewidth and thermal resistance measurements; device modeling; dopant density profiles; resonance ionization spectroscopy; and deep level measurements. Standardized oxide charge terminology is also described.

Infrared control coating of thin film devices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Berland, Brian Spencer; Stowell, Jr., Michael Wayne; Hollingsworth, Russell

Systems and methods for creating an infrared-control coated thin film device with certain visible light transmittance and infrared reflectance properties are disclosed. The device may be made using various techniques including physical vapor deposition, chemical vapor deposition, thermal evaporation, pulsed laser deposition, sputter deposition, and sol-gel processes. In particular, a pulsed energy microwave plasma enhanced chemical vapor deposition process may be used. Production of the device may occur at speeds greater than 50 Angstroms/second and temperatures lower than 200.degree. C.

Towards phase-coherent caloritronics in superconducting circuits

NASA Astrophysics Data System (ADS)

Fornieri, Antonio; Giazotto, Francesco

2017-10-01

The emerging field of phase-coherent caloritronics (from the Latin word calor, heat) is based on the possibility of controlling heat currents by using the phase difference of the superconducting order parameter. The goal is to design and implement thermal devices that can control energy transfer with a degree of accuracy approaching that reached for charge transport by contemporary electronic components. This can be done by making use of the macroscopic quantum coherence intrinsic to superconducting condensates, which manifests itself through the Josephson effect and the proximity effect. Here, we review recent experimental results obtained in the realization of heat interferometers and thermal rectifiers, and discuss a few proposals for exotic nonlinear phase-coherent caloritronic devices, such as thermal transistors, solid-state memories, phase-coherent heat splitters, microwave refrigerators, thermal engines and heat valves. Besides being attractive from the fundamental physics point of view, these systems are expected to have a vast impact on many cryogenic microcircuits requiring energy management, and possibly lay the first stone for the foundation of electronic thermal logic.

Towards phase-coherent caloritronics in superconducting circuits.

PubMed

Fornieri, Antonio; Giazotto, Francesco

2017-10-06

The emerging field of phase-coherent caloritronics (from the Latin word calor, heat) is based on the possibility of controlling heat currents by using the phase difference of the superconducting order parameter. The goal is to design and implement thermal devices that can control energy transfer with a degree of accuracy approaching that reached for charge transport by contemporary electronic components. This can be done by making use of the macroscopic quantum coherence intrinsic to superconducting condensates, which manifests itself through the Josephson effect and the proximity effect. Here, we review recent experimental results obtained in the realization of heat interferometers and thermal rectifiers, and discuss a few proposals for exotic nonlinear phase-coherent caloritronic devices, such as thermal transistors, solid-state memories, phase-coherent heat splitters, microwave refrigerators, thermal engines and heat valves. Besides being attractive from the fundamental physics point of view, these systems are expected to have a vast impact on many cryogenic microcircuits requiring energy management, and possibly lay the first stone for the foundation of electronic thermal logic.

MEMS Louvers for Thermal Control

NASA Technical Reports Server (NTRS)

Champion, J. L.; Osiander, R.; Darrin, M. A. Garrison; Swanson, T. D.

1998-01-01

Mechanical louvers have frequently been used for spacecraft and instrument thermal control purposes. These devices typically consist of parallel or radial vanes, which can be opened or closed to vary the effective emissivity of the underlying surface. This project demonstrates the feasibility of using Micro-Electromechanical Systems (MEMS) technology to miniaturize louvers for such purposes. This concept offers the possibility of substituting the smaller, lighter weight, more rugged, and less costly MEMS devices for such mechanical louvers. In effect, a smart skin that self adjusts in response to environmental influences could be developed composed of arrays of thousands of miniaturized louvers. Several orders of magnitude size, weight, and volume decreases are potentially achieved using micro-electromechanical techniques. The use of this technology offers substantial benefits in spacecraft/instrument design, integration and testing, and flight operations. It will be particularly beneficial for the emerging smaller spacecraft and instruments of the future. In addition, this MEMS thermal louver technology can form the basis for related spacecraft instrument applications. The specific goal of this effort was to develop a preliminary MEMS device capable of modulating the effective emissivity of radiators on spacecraft. The concept pursued uses hinged panels, or louvers, in a manner such that heat emitted from the radiators is a function of louver angle. An electrostatic comb drive or other such actuator can control the louver position. The initial design calls for the louvers to be gold coated while the underlying surface is of high emissivity. Since, the base MEMS material, silicon, is transparent in the InfraRed (IR) spectrum, the device has a minimum emissivity when closed and a maximum emissivity when open. An initial set of polysilicon louver devices was designed at the Johns Hopkins Applied Physics Laboratory in conjunction with the Thermal Engineering Branch at NASA's Goddard Space Flight Center.

Space thermal control development

NASA Technical Reports Server (NTRS)

Hoover, M. J.; Grodzka, P. G.; Oneill, M. J.

1971-01-01

The results of experimental investigations on a number of various phase change materials (PCMs) and PCMs in combination with metals and other materials are reported. The evaluations include the following PCM system performance characteristics: PCM and PCM/filler thermal diffusivities, the effects of long-term thermal cycling, PCM-container compatibility, and catalyst effectiveness and stability. Three PCMs demonstrated performance acceptable enough to be considered for use in prototype aluminum thermal control devices. These three PCMs are lithium nitrate trihydrate with zinc hydroxy nitrate catalyst, acetamide, and myristic acid. Of the fillers tested, aluminum honeycomb filler was found to offer the most increase in system thermal diffusivity.

40 CFR Table 1 to Subpart Sssss of... - Emission Limits

Code of Federal Regulations, 2012 CFR

2012-07-01

... that are controlled with a thermal or catalytic oxidizer a. The 3-hour block average THC concentration... the outlet of the control device; or b. The 3-hour block average THC mass emissions rate must be... than a thermal or catalytic oxidizer a. The 3-hour block average THC concentration must not exceed 20...

40 CFR Table 1 to Subpart Sssss of... - Emission Limits

Code of Federal Regulations, 2013 CFR

2013-07-01

... that are controlled with a thermal or catalytic oxidizer a. The 3-hour block average THC concentration... the outlet of the control device; or b. The 3-hour block average THC mass emissions rate must be... than a thermal or catalytic oxidizer a. The 3-hour block average THC concentration must not exceed 20...

40 CFR Table 1 to Subpart Sssss of... - Emission Limits

Code of Federal Regulations, 2014 CFR

2014-07-01

... that are controlled with a thermal or catalytic oxidizer a. The 3-hour block average THC concentration... the outlet of the control device; or b. The 3-hour block average THC mass emissions rate must be... than a thermal or catalytic oxidizer a. The 3-hour block average THC concentration must not exceed 20...

40 CFR Table 1 to Subpart Sssss of... - Emission Limits

Code of Federal Regulations, 2011 CFR

2011-07-01

... that are controlled with a thermal or catalytic oxidizer a. The 3-hour block average THC concentration... the outlet of the control device; or b. The 3-hour block average THC mass emissions rate must be... than a thermal or catalytic oxidizer a. The 3-hour block average THC concentration must not exceed 20...

40 CFR Table 1 to Subpart Sssss of... - Emission Limits

Code of Federal Regulations, 2010 CFR

2010-07-01

... that are controlled with a thermal or catalytic oxidizer a. The 3-hour block average THC concentration... the outlet of the control device; or b. The 3-hour block average THC mass emissions rate must be... than a thermal or catalytic oxidizer a. The 3-hour block average THC concentration must not exceed 20...

Gas reservoir and a method to supply gas to plasma tubes

DOEpatents

Stautner, Ernst Wolfgang; Michael, Joseph Darryl

2017-01-31

A reservoir for storing and supplying a portion of a reservoir gas into a gas-filled tube is presented. The reservoir includes a first vessel having a thermally conductive surface, a meshed vessel having a lid, and placed inside the first vessel to form a cavity between the meshed vessel and the first vessel, at least one tray placed inside the meshed vessel to divide an inner space of the meshed vessel into a plurality of compartments, a sorbent material placed inside the plurality of compartments in the meshed vessel, a temperature control device positioned such that a first portion of the temperature control device is in physical contact with at least a portion of the thermally conductive surface, and a change in the temperature of the temperature control device changes the temperature of the sorbent material, wherein the reservoir gas is retained by the sorbent material at the storage temperature.

Using a Tandem Pelletron accelerator to produce a thermal neutron beam for detector testing purposes.

PubMed

Irazola, L; Praena, J; Fernández, B; Macías, M; Bedogni, R; Terrón, J A; Sánchez-Nieto, B; Arias de Saavedra, F; Porras, I; Sánchez-Doblado, F

2016-01-01

Active thermal neutron detectors are used in a wide range of measuring devices in medicine, industry and research. For many applications, the long-term stability of these devices is crucial, so that very well controlled neutron fields are needed to perform calibrations and repeatability tests. A way to achieve such reference neutron fields, relying on a 3 MV Tandem Pelletron accelerator available at the CNA (Seville, Spain), is reported here. This paper shows thermal neutron field production and reproducibility characteristics over few days. Copyright © 2015 Elsevier Ltd. All rights reserved.

Analytical transient analysis of Peltier device for laser thermal tuning

NASA Astrophysics Data System (ADS)

Sheikhnejad, Yahya; Vujicic, Zoran; Almeida, Álvaro J.; Bastos, Ricardo; Shahpari, Ali; Teixeira, António L.

2017-08-01

Recently, industrial trends strongly favor the concepts of high density, low power consumption and low cost applications of Datacom and Telecom pluggable transceiver modules. Hence, thermal management plays an important role, especially in the design of high-performance compact optical transceivers. Extensive care should be taken on wavelength drift for thermal tuning lasers using thermoelectric cooler and indeed, accurate expression is needed to describe transient characteristics of the Peltier device to achieve maximum controllability. In this study, the exact solution of governing equation is presented, considering Joule heating, heat conduction, heat flux of laser diode and thermoelectric effect in one dimension.

A new solution of measuring thermal response of prestressed concrete bridge girders for structural health monitoring

NASA Astrophysics Data System (ADS)

Jiao, Pengcheng; Borchani, Wassim; Hasni, Hassene; Lajnef, Nizar

2017-08-01

This study develops a novel buckling-based mechanism to measure the thermal response of prestressed concrete bridge girders under continuous temperature changes for structural health monitoring. The measuring device consists of a bilaterally constrained beam and a piezoelectric polyvinylidene fluoride transducer that is attached to the beam. Under thermally induced displacement, the slender beam is buckled. The post-buckling events are deployed to convert the low-rate and low-frequency excitations into localized high-rate motions and, therefore, the attached piezoelectric transducer is triggered to generate electrical signals. Attaching the measuring device to concrete bridge girders, the electrical signals are used to detect the thermal response of concrete bridges. Finite element simulations are conducted to obtain the displacement of prestressed concrete girders under thermal loads. Using the thermal-induced displacement as input, experiments are carried out on a 3D printed measuring device to investigate the buckling response and corresponding electrical signals. A theoretical model is developed based on the nonlinear Euler-Bernoulli beam theory and large deformation assumptions to predict the buckling mode transitions of the beam. Based on the presented theoretical model, the geometry properties of the measuring device can be designed such that its buckling response is effectively controlled. Consequently, the thermally induced displacement can be designed as limit states to detect excessive thermal loads on concrete bridge girders. The proposed solution sufficiently measures the thermal response of concrete bridges.

A design handbook for phase change thermal control and energy storage devices. [selected paraffins

NASA Technical Reports Server (NTRS)

Humphries, W. R.; Griggs, E. I.

1977-01-01

Comprehensive survey is given of the thermal aspects of phase change material devices. Fundamental mechanisms of heat transfer within the phase change device are discussed. Performance in zero-g and one-g fields are examined as it relates to such a device. Computer models for phase change materials, with metal fillers, undergoing conductive and convective processes are detailed. Using these models, extensive parametric data are presented for a hypothetical configuration with a rectangular phase change housing, using straight fins as the filler, and paraffin as the phase change material. These data are generated over a range of realistic sizes, material properties, and thermal boundary conditions. A number of illustrative examples are given to demonstrate use of the parametric data. Also, a complete listing of phase change material property data are reproduced herein as an aid to the reader.

Controlled ripple texturing of suspended graphene and ultrathin graphite membranes.

PubMed

Bao, Wenzhong; Miao, Feng; Chen, Zhen; Zhang, Hang; Jang, Wanyoung; Dames, Chris; Lau, Chun Ning

2009-09-01

Graphene is nature's thinnest elastic material and displays exceptional mechanical and electronic properties. Ripples are an intrinsic feature of graphene sheets and are expected to strongly influence electronic properties by inducing effective magnetic fields and changing local potentials. The ability to control ripple structure in graphene could allow device design based on local strain and selective bandgap engineering. Here, we report the first direct observation and controlled creation of one- and two-dimensional periodic ripples in suspended graphene sheets, using both spontaneously and thermally generated strains. We are able to control ripple orientation, wavelength and amplitude by controlling boundary conditions and making use of graphene's negative thermal expansion coefficient (TEC), which we measure to be much larger than that of graphite. These results elucidate the ripple formation process, which can be understood in terms of classical thin-film elasticity theory. This should lead to an improved understanding of suspended graphene devices, a controlled engineering of thermal stress in large-scale graphene electronics, and a systematic investigation of the effect of ripples on the electronic properties of graphene.

Patternable PEDOT nanofilms with grid electrodes for transparent electrochromic devices targeting thermal camouflage.

PubMed

Kim, Bumsoo; Koh, Jong Kwan; Park, Junyong; Ahn, Changui; Ahn, Joonmo; Kim, Jong Hak; Jeon, Seokwoo

2015-01-01

This paper reports a new type of transmitting mode electrochromic device that uses the high-contrast electrochromism of poly(3,4-ethylenedioxythiophene) (PEDOT) and operates at long-wavelength infrared (8-12 μm) . To maximize the transmittance contrast and transmittance contrast ratio of the device for thermal camouflage, we control the thickness of the thin PEDOT layer from 25 nm to 400 nm and develop a design of grid-type counter electrodes. The cyclability can be greatly improved by selective deposition of the PEDOT film on grid electrodes as an ion storage layer without any loss of overall transmittance. The device with optimized architectures shows a high transmittance contrast ratio of 83 % at a wavelength of 10 μm with a response rate under 1.4 s when alternating voltage is applied. Captured images of an LED lamp behind the device prove the possibility of active, film-type camouflage against thermal detection.

Tunable reflectance of an inverse opal-chiral nematic liquid crystal multilayer device by electric- or thermal-control.

PubMed

Zhang, Yuxian; Zhao, Weidong; Wen, Jiahui; Li, Jinming; Yang, Zhou; Wang, Dong; Cao, Hui; Quan, Maohua

2017-05-21

A new type of electric- or thermal-responsive multilayer device composed of SiO 2 bilayer inverse opal (IOP) and chiral nematic liquid crystals (N*LCs) was developed. Bilayer IOP was fabricated by layer-by-layer assembly of polystyrene (PS) spheres with two different sizes and showed a reflectance in an extended range of the near-infrared region. Furthermore, the electrically or thermally tunable reflectance of the bilayer-IOP-N*LC device was investigated. The device exhibited the photonic bandgap (PBG) of the N*LC-IOP composite structure with the application of an electric field (voltage-on), while it presented the reflectance of N*LCs without an electric field (voltage-off) and the electrically-responsive behaviour could be reversibly switched. Besides, the device exhibited a gradient redshift of reflectance as temperature increased below the clearing point (T C ) while it showed the PBG of the N*LC-IOP composite structure when the temperature was above T C .

Flow Control and Measurement in Electric Propulsion Systems: Towards an AIAA Reference Standard

DTIC Science & Technology

2013-10-01

the spacecraft sensors, although some improvement can be made by averaging several measurements together. 3. Thermal Mass Gauging Thermal Mass...flow controllers (MFCs) to measure and control propellant into EP devices. To determine several key thruster performance parameters with a low level...the specified time interval may not be known. A first recourse is to perform several measurements and examine the linearity. In cases where the

Cooled, temperature controlled electrometer

DOEpatents

Morgan, John P.

1992-01-01

A cooled, temperature controlled electrometer for the measurement of small currents. The device employs a thermal transfer system to remove heat from the electrometer circuit and its environment and dissipate it to the external environment by means of a heat sink. The operation of the thermal transfer system is governed by a temperature regulation circuit which activates the thermal transfer system when the temperature of the electrometer circuit and its environment exceeds a level previously inputted to the external variable temperature control circuit. The variable temperature control circuit functions as subpart of the temperature control circuit. To provide temperature stability and uniformity, the electrometer circuit is enclosed by an insulated housing.

Cooled, temperature controlled electrometer

DOEpatents

Morgan, John P.

1992-08-04

A cooled, temperature controlled electrometer for the measurement of small currents. The device employs a thermal transfer system to remove heat from the electrometer circuit and its environment and dissipate it to the external environment by means of a heat sink. The operation of the thermal transfer system is governed by a temperature regulation circuit which activates the thermal transfer system when the temperature of the electrometer circuit and its environment exceeds a level previously inputted to the external variable temperature control circuit. The variable temperature control circuit functions as subpart of the temperature control circuit. To provide temperature stability and uniformity, the electrometer circuit is enclosed by an insulated housing.

Development of high frequency low weight power magnetics for aerospace power systems

NASA Technical Reports Server (NTRS)

Schwarze, G. E.

1984-01-01

A dominant design consideration in the development of space type power mangetic devices is the application of reliable thermal control methods to prevent device failure which is due to excessive temperature rises and hot temperatures in critical areas. The resultant design must also yield low weight, high efficiency, high reliability and maintainability, and long life. The weight savings and high efficiency that results by going to high frequency and unique thermal control techniques is demonstrated by the development of a 25 kVA, 20 kHz space type transformer under the power magnetics technology program. Work in the area of power rotary transformer is also discussed.

Ultralow thermal conductivity in all-inorganic halide perovskites

PubMed Central

Li, Huashan; Wong, Andrew B.; Zhang, Dandan; Lai, Minliang; Yu, Yi; Kong, Qiao; Lin, Elbert; Urban, Jeffrey J.; Grossman, Jeffrey C.; Yang, Peidong

2017-01-01

Controlling the flow of thermal energy is crucial to numerous applications ranging from microelectronic devices to energy storage and energy conversion devices. Here, we report ultralow lattice thermal conductivities of solution-synthesized, single-crystalline all-inorganic halide perovskite nanowires composed of CsPbI3 (0.45 ± 0.05 W·m−1·K−1), CsPbBr3 (0.42 ± 0.04 W·m−1·K−1), and CsSnI3 (0.38 ± 0.04 W·m−1·K−1). We attribute this ultralow thermal conductivity to the cluster rattling mechanism, wherein strong optical–acoustic phonon scatterings are driven by a mixture of 0D/1D/2D collective motions. Remarkably, CsSnI3 possesses a rare combination of ultralow thermal conductivity, high electrical conductivity (282 S·cm−1), and high hole mobility (394 cm2·V−1·s−1). The unique thermal transport properties in all-inorganic halide perovskites hold promise for diverse applications such as phononic and thermoelectric devices. Furthermore, the insights obtained from this work suggest an opportunity to discover low thermal conductivity materials among unexplored inorganic crystals beyond caged and layered structures. PMID:28760988

Ultralow thermal conductivity in all-inorganic halide perovskites

DOE PAGES

Lee, Woochul; Li, Huashan; Wong, Andrew B.; ...

2017-07-08

Controlling the flow of thermal energy is crucial to numerous applications ranging from microelectronic devices to energy storage and energy conversion devices. Here in this paper, we report ultralow lattice thermal conductivities of solution-synthesized, single-crystalline all-inorganic halide perovskite nanowires composed of CsPbI 3 (0.45 ± 0.05 W·m -1 ·K -1), CsPbBr 3 (0.42 ± 0.04 W·m -1·K -1), and CsSnI 3 (0.38 ± 0.04 W·m -1 ·K -1). We attribute this ultralow thermal conductivity to the cluster rattling mechanism, wherein strong optical–acoustic phonon scatterings are driven by a mixture of 0D/1D/2D collective motions. Remarkably, CsSnI 3 possesses a rare combinationmore » of ultralow thermal conductivity, high electrical conductivity (282 S·cm -1), and high hole mobility (394 cm 2 ·V -1 ·s -1). The unique thermal transport properties in all-inorganic halide perovskites hold promise for diverse applications such as phononic and thermoelectric devices. Furthermore, the insights obtained from this work suggest an opportunity to discover low thermal conductivity materials among unexplored inorganic crystals beyond caged and layered structures.« less

Ultralow thermal conductivity in all-inorganic halide perovskites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Woochul; Li, Huashan; Wong, Andrew B.

Controlling the flow of thermal energy is crucial to numerous applications ranging from microelectronic devices to energy storage and energy conversion devices. Here in this paper, we report ultralow lattice thermal conductivities of solution-synthesized, single-crystalline all-inorganic halide perovskite nanowires composed of CsPbI 3 (0.45 ± 0.05 W·m -1 ·K -1), CsPbBr 3 (0.42 ± 0.04 W·m -1·K -1), and CsSnI 3 (0.38 ± 0.04 W·m -1 ·K -1). We attribute this ultralow thermal conductivity to the cluster rattling mechanism, wherein strong optical–acoustic phonon scatterings are driven by a mixture of 0D/1D/2D collective motions. Remarkably, CsSnI 3 possesses a rare combinationmore » of ultralow thermal conductivity, high electrical conductivity (282 S·cm -1), and high hole mobility (394 cm 2 ·V -1 ·s -1). The unique thermal transport properties in all-inorganic halide perovskites hold promise for diverse applications such as phononic and thermoelectric devices. Furthermore, the insights obtained from this work suggest an opportunity to discover low thermal conductivity materials among unexplored inorganic crystals beyond caged and layered structures.« less

Ultralow thermal conductivity in all-inorganic halide perovskites.

PubMed

Lee, Woochul; Li, Huashan; Wong, Andrew B; Zhang, Dandan; Lai, Minliang; Yu, Yi; Kong, Qiao; Lin, Elbert; Urban, Jeffrey J; Grossman, Jeffrey C; Yang, Peidong

2017-08-15

Controlling the flow of thermal energy is crucial to numerous applications ranging from microelectronic devices to energy storage and energy conversion devices. Here, we report ultralow lattice thermal conductivities of solution-synthesized, single-crystalline all-inorganic halide perovskite nanowires composed of CsPbI 3 (0.45 ± 0.05 W·m -1 ·K -1 ), CsPbBr 3 (0.42 ± 0.04 W·m -1 ·K -1 ), and CsSnI 3 (0.38 ± 0.04 W·m -1 ·K -1 ). We attribute this ultralow thermal conductivity to the cluster rattling mechanism, wherein strong optical-acoustic phonon scatterings are driven by a mixture of 0D/1D/2D collective motions. Remarkably, CsSnI 3 possesses a rare combination of ultralow thermal conductivity, high electrical conductivity (282 S·cm -1 ), and high hole mobility (394 cm 2 ·V -1 ·s -1 ). The unique thermal transport properties in all-inorganic halide perovskites hold promise for diverse applications such as phononic and thermoelectric devices. Furthermore, the insights obtained from this work suggest an opportunity to discover low thermal conductivity materials among unexplored inorganic crystals beyond caged and layered structures.

Computer control of a scanning electron microscope for digital image processing of thermal-wave images

NASA Technical Reports Server (NTRS)

Gilbert, Percy; Jones, Robert E.; Kramarchuk, Ihor; Williams, Wallace D.; Pouch, John J.

1987-01-01

Using a recently developed technology called thermal-wave microscopy, NASA Lewis Research Center has developed a computer controlled submicron thermal-wave microscope for the purpose of investigating III-V compound semiconductor devices and materials. This paper describes the system's design and configuration and discusses the hardware and software capabilities. Knowledge of the Concurrent 3200 series computers is needed for a complete understanding of the material presented. However, concepts and procedures are of general interest.

Thermal-Wave Microscope

NASA Technical Reports Server (NTRS)

Jones, Robert E.; Kramarchuk, Ihor; Williams, Wallace D.; Pouch, John J.; Gilbert, Percy

1989-01-01

Computer-controlled thermal-wave microscope developed to investigate III-V compound semiconductor devices and materials. Is nondestructive technique providing information on subsurface thermal features of solid samples. Furthermore, because this is subsurface technique, three-dimensional imaging also possible. Microscope uses intensity-modulated electron beam of modified scanning electron microscope to generate thermal waves in sample. Acoustic waves generated by thermal waves received by transducer and processed in computer to form images displayed on video display of microscope or recorded on magnetic disk.

Cryogenic Technology Development for Exploration Missions

NASA Technical Reports Server (NTRS)

Chato, David J.

2007-01-01

This paper reports the status and findings of different cryogenic technology research projects in support of the President s Vision for Space Exploration. The exploration systems architecture study is reviewed for cryogenic fluid management needs. It is shown that the exploration architecture is reliant on the cryogenic propellants of liquid hydrogen, liquid oxygen and liquid methane. Needs identified include: the key technologies of liquid acquisition devices, passive thermal and pressure control, low gravity mass gauging, prototype pressure vessel demonstration, active thermal control; as well as feed system testing, and Cryogenic Fluid Management integrated system demonstration. Then five NASA technology projects are reviewed to show how these needs are being addressed by technology research. Projects reviewed include: In-Space Cryogenic Propellant Depot; Experimentation for the Maturation of Deep Space Cryogenic Refueling Technology; Cryogenic Propellant Operations Demonstrator; Zero Boil-Off Technology Experiment; and Propulsion and Cryogenic Advanced Development. Advances are found in the areas of liquid acquisition of liquid oxygen, mass gauging of liquid oxygen via radio frequency techniques, computational modeling of thermal and pressure control, broad area cooling thermal control strategies, flight experiments for resolving low gravity issues of cryogenic fluid management. Promising results are also seen for Joule-Thomson pressure control devices in liquid oxygen and liquid methane and liquid acquisition of methane, although these findings are still preliminary.

Control and design heat flux bending in thermal devices with transformation optics.

PubMed

Xu, Guoqiang; Zhang, Haochun; Jin, Yan; Li, Sen; Li, Yao

2017-04-17

We propose a fundamental latent function of control heat transfer and heat flux density vectors at random positions on thermal materials by applying transformation optics. The expressions for heat flux bending are obtained, and the factors influencing them are investigated in both 2D and 3D cloaking schemes. Under certain conditions, more than one degree of freedom of heat flux bending exists corresponding to the temperature gradients of the 3D domain. The heat flux path can be controlled in random space based on the geometrical azimuths, radial positions, and thermal conductivity ratios of the selected materials.

DOE Office of Scientific and Technical Information (OSTI.GOV)

He, Xiao; Wu, Linzhi, E-mail: wlz@hit.edu.cn

The previously reported magical thermal devices, such as the thermal invisible cloak and the thermal concentrator, are generalized into one general case named here thermal illusion device. The thermal illusion device is displayed by the design of a thermal reshaper which can reshape an arbitrary thermal object into another one with arbitrary cross section. General expressions of the material parameters for the thermal reshaper are derived unambiguously to greatly facilitate the design of general thermal illusion device. We believe that this work will broaden the current research and pave a path to the thermal invisibility. Numerical simulations show good agreementmore » with the analytical results of the thermal illusion device.« less

Evidence of thermal transport anisotropy in stable glasses of vapor deposited organic molecules

NASA Astrophysics Data System (ADS)

Ràfols-Ribé, Joan; Dettori, Riccardo; Ferrando-Villalba, Pablo; Gonzalez-Silveira, Marta; Abad, Llibertat; Lopeandía, Aitor F.; Colombo, Luciano; Rodríguez-Viejo, Javier

2018-03-01

Vapor deposited organic glasses are currently in use in many optoelectronic devices. Their operation temperature is limited by the glass transition temperature of the organic layers and thermal management strategies become increasingly important to improve the lifetime of the device. Here we report the unusual finding that molecular orientation heavily influences heat flow propagation in glassy films of small molecule organic semiconductors. The thermal conductivity of vapor deposited thin-film semiconductor glasses is anisotropic and controlled by the deposition temperature. We compare our data with extensive molecular dynamics simulations to disentangle the role of density and molecular orientation on heat propagation. Simulations do support the view that thermal transport along the backbone of the organic molecule is strongly preferred with respect to the perpendicular direction. This is due to the anisotropy of the molecular interaction strength that limits the transport of atomic vibrations. This approach could be used in future developments to implement small molecule glassy films in thermoelectric or other organic electronic devices.

Epidermal photonic devices for quantitative imaging of temperature and thermal transport characteristics of the skin

NASA Astrophysics Data System (ADS)

Gao, Li; Zhang, Yihui; Malyarchuk, Viktor; Jia, Lin; Jang, Kyung-In; Chad Webb, R.; Fu, Haoran; Shi, Yan; Zhou, Guoyan; Shi, Luke; Shah, Deesha; Huang, Xian; Xu, Baoxing; Yu, Cunjiang; Huang, Yonggang; Rogers, John A.

2014-09-01

Characterization of temperature and thermal transport properties of the skin can yield important information of relevance to both clinical medicine and basic research in skin physiology. Here we introduce an ultrathin, compliant skin-like, or ‘epidermal’, photonic device that combines colorimetric temperature indicators with wireless stretchable electronics for thermal measurements when softly laminated on the skin surface. The sensors exploit thermochromic liquid crystals patterned into large-scale, pixelated arrays on thin elastomeric substrates; the electronics provide means for controlled, local heating by radio frequency signals. Algorithms for extracting patterns of colour recorded from these devices with a digital camera and computational tools for relating the results to underlying thermal processes near the skin surface lend quantitative value to the resulting data. Application examples include non-invasive spatial mapping of skin temperature with milli-Kelvin precision (±50 mK) and sub-millimetre spatial resolution. Demonstrations in reactive hyperaemia assessments of blood flow and hydration analysis establish relevance to cardiovascular health and skin care, respectively.

Epidermal photonic devices for quantitative imaging of temperature and thermal transport characteristics of the skin.

PubMed

Gao, Li; Zhang, Yihui; Malyarchuk, Viktor; Jia, Lin; Jang, Kyung-In; Webb, R Chad; Fu, Haoran; Shi, Yan; Zhou, Guoyan; Shi, Luke; Shah, Deesha; Huang, Xian; Xu, Baoxing; Yu, Cunjiang; Huang, Yonggang; Rogers, John A

2014-09-19

Characterization of temperature and thermal transport properties of the skin can yield important information of relevance to both clinical medicine and basic research in skin physiology. Here we introduce an ultrathin, compliant skin-like, or 'epidermal', photonic device that combines colorimetric temperature indicators with wireless stretchable electronics for thermal measurements when softly laminated on the skin surface. The sensors exploit thermochromic liquid crystals patterned into large-scale, pixelated arrays on thin elastomeric substrates; the electronics provide means for controlled, local heating by radio frequency signals. Algorithms for extracting patterns of colour recorded from these devices with a digital camera and computational tools for relating the results to underlying thermal processes near the skin surface lend quantitative value to the resulting data. Application examples include non-invasive spatial mapping of skin temperature with milli-Kelvin precision (±50 mK) and sub-millimetre spatial resolution. Demonstrations in reactive hyperaemia assessments of blood flow and hydration analysis establish relevance to cardiovascular health and skin care, respectively.

Ex vivo evaluation of super pulse diode laser system with smart temperature feedback for contact soft-tissue surgery

NASA Astrophysics Data System (ADS)

Yaroslavsky, Ilya; Boutoussov, Dmitri; Vybornov, Alexander; Perchuk, Igor; Meleshkevich, Val; Altshuler, Gregory

2018-02-01

Until recently, Laser Diodes (LD) have been limited in their ability to deliver high peak power levels, which, in turn, limited their clinical capabilities. New technological developments made possible advent of "super pulse" LD (SPLD). Moreover, advanced means of smart thermal feedback enable precise control of laser power, thus ensuring safe and optimally efficacious application. In this work, we have evaluated a prototype SPLD system ex vivo. The device provided up to 25 W average and up to 150 W pulse power at 940 nm wavelength. The laser was operated in the thermal feedback-controlled mode, where power of the laser was varied automatically as a function of real-time thermal feedback to maintain constant tip temperature. The system was also equipped with a fiber tip initiated with advanced TiO2 /tungsten technique. Evaluation methods were designed to assess: 1) Speed and depth of cutting; 2) Dimensions of coagulative margin. The SPLD system was compared with industry-leading conventional diode and CO2 devices. The results indicate that the SPLD system provides increase in speed of controlled cutting by a factor of >2 in comparison with the conventional diode laser and approaching that of CO2 device. The produced ratio of the depth of cut to the thermal damage margin was significantly higher than conventional diodes and close to that of the CO2 system, suggesting optimal hemostasis conditions. SPLD technology with real-time temperature control has a potential for creating a new standard of care in the field of precision soft tissue surgery.

Thermal Spray Applications in Electronics and Sensors: Past, Present, and Future

NASA Astrophysics Data System (ADS)

Sampath, Sanjay

2010-09-01

Thermal spray has enjoyed unprecedented growth and has emerged as an innovative and multifaceted deposition technology. Thermal spray coatings are crucial to the enhanced utilization of various engineering systems. Industries, in recognition of thermal spray's versatility and economics, have introduced it into manufacturing environments. The majority of modern thermal spray applications are "passive" protective coatings, and they rarely perform an electronic function. The ability to consolidate dissimilar material multilayers without substrate thermal loading has long been considered a virtue for thick-film electronics. However, the complexity of understanding/controlling materials functions especially those resulting from rapid solidification and layered assemblage has stymied expansion into electronics. That situation is changing: enhancements in process/material science are allowing reconsideration for novel electronic/sensor devices. This review critically examines past efforts in terms of materials functionality from a device perspective, along with ongoing/future concepts addressing the aforementioned deficiencies. The analysis points to intriguing future possibilities for thermal spray technology in the world of thick-film sensors.

Illusion thermal device based on material with constant anisotropic thermal conductivity for location camouflage

NASA Astrophysics Data System (ADS)

Hou, Quanwen; Zhao, Xiaopeng; Meng, Tong; Liu, Cunliang

2016-09-01

Thermal metamaterials and devices based on transformation thermodynamics often require materials with anisotropic and inhomogeneous thermal conductivities. In this study, still based on the concept of transformation thermodynamics, we designed a planar illusion thermal device, which can delocalize a heat source in the device such that the temperature profile outside the device appears to be produced by a virtual source at another position. This device can be constructed by only one kind of material with constant anisotropic thermal conductivity. The condition which should be satisfied by the device is provided, and the required anisotropic thermal conductivity is then deduced theoretically. This study may be useful for the designs of metamaterials or devices since materials with constant anisotropic parameters have great facility in fabrication. A prototype device has been fabricated based on a composite composed by two naturally occurring materials. The experimental results validate the effectiveness of the device.

Sound and heat revolutions in phononics

NASA Astrophysics Data System (ADS)

Maldovan, Martin

2013-11-01

The phonon is the physical particle representing mechanical vibration and is responsible for the transmission of everyday sound and heat. Understanding and controlling the phononic properties of materials provides opportunities to thermally insulate buildings, reduce environmental noise, transform waste heat into electricity and develop earthquake protection. Here I review recent progress and the development of new ideas and devices that make use of phononic properties to control both sound and heat. Advances in sonic and thermal diodes, optomechanical crystals, acoustic and thermal cloaking, hypersonic phononic crystals, thermoelectrics, and thermocrystals herald the next technological revolution in phononics.

Controlling Thermal Expansion: A Metal–Organic Frameworks Route

PubMed Central

2016-01-01

Controlling thermal expansion is an important, not yet resolved, and challenging problem in materials research. A conceptual design is introduced here, for the first time, for the use of metal–organic frameworks (MOFs) as platforms for controlling thermal expansion devices that can operate in the negative, zero, and positive expansion regimes. A detailed computer simulation study, based on molecular dynamics, is presented to support the targeted application. MOF-5 has been selected as model material, along with three molecules of similar size and known differences in terms of the nature of host–guest interactions. It has been shown that adsorbate molecules can control, in a colligative way, the thermal expansion of the solid, so that changing the adsorbate molecules induces the solid to display positive, zero, or negative thermal expansion. We analyze in depth the distortion mechanisms, beyond the ligand metal junction, to cover the ligand distortions, and the energetic and entropic effect on the thermo-structural behavior. We provide an unprecedented atomistic insight on the effect of adsorbates on the thermal expansion of MOFs as a basic tool toward controlling the thermal expansion. PMID:28190918

Flow Visualization Study of Natural Convection from a Heated Protrusion in a Liquid Filled Rectangular Enclosure.

DTIC Science & Technology

1983-12-01

PROPOSED SOLUTIONS Many papers have been published outlining alternative methods of thermally controlling microelectronic devices. Hannemann [3] describes...Workshop, NSF Grant ENG-7701297, Directions of Heat Transfer in Electronic Equipment, Fy R. C. Chu, 1977. 3. Hannemann , R., "Electronic System Thermal

Manipulating Steady Heat Conduction by Sensu-shaped Thermal Metamaterials

PubMed Central

Han, Tiancheng; Bai, Xue; Liu, Dan; Gao, Dongliang; Li, Baowen; Thong, John T. L.; Qiu, Cheng-Wei

2015-01-01

The ability to design the control of heat flow has innumerable benefits in the design of electronic systems such as thermoelectric energy harvesters, solid-state lighting, and thermal imagers, where the thermal design plays a key role in performance and device reliability. In this work, we employ one identical sensu-unit with facile natural composition to experimentally realize a new class of thermal metamaterials for controlling thermal conduction (e.g., thermal concentrator, focusing/resolving, uniform heating), only resorting to positioning and locating the same unit element of sensu-shape structure. The thermal metamaterial unit and the proper arrangement of multiple identical units are capable of transferring, redistributing and managing thermal energy in a versatile fashion. It is also shown that our sensu-shape unit elements can be used in manipulating dc currents without any change in the layout for the thermal counterpart. These could markedly enhance the capabilities in thermal sensing, thermal imaging, thermal-energy storage, thermal packaging, thermal therapy, and more domains beyond. PMID:25974383

Time-Separating Heating and Sensor Functions of Thermistors in Precision Thermal Control Applications

NASA Technical Reports Server (NTRS)

Cho, Hyung J.; Sukhatme, Kalyani G.; Mahoney, John C.; Penanen, Konstantin Penanen; Vargas, Rudolph, Jr.

2010-01-01

A method allows combining the functions of a heater and a thermometer in a single device, a thermistor, with minimal temperature read errors. Because thermistors typically have a much smaller thermal mass than the objects they monitor, the thermal time to equilibrate the thermometer to the temperature of the object is typically much shorter than the thermal time of the object to change its temperature in response to an external perturbation.

Temperature control of power semiconductor devices in traction applications

NASA Astrophysics Data System (ADS)

Pugachev, A. A.; Strekalov, N. N.

2017-02-01

The peculiarity of thermal management of traction frequency converters of a railway rolling stock is highlighted. The topology and the operation principle of the automatic temperature control system of power semiconductor modules of the traction frequency converter are designed and discussed. The features of semiconductors as an object of temperature control are considered; the equivalent circuit of thermal processes in the semiconductors is suggested, the power losses in the two-level voltage source inverters are evaluated and analyzed. The dynamic properties and characteristics of the cooling fan induction motor electric drive with the scalar control are presented. The results of simulation in Matlab are shown for the steady state of thermal processes.

Engineering thermal conductance using a two-dimensional phononic crystal.

PubMed

Zen, Nobuyuki; Puurtinen, Tuomas A; Isotalo, Tero J; Chaudhuri, Saumyadip; Maasilta, Ilari J

2014-03-19

Controlling thermal transport has become relevant in recent years. Traditionally, this control has been achieved by tuning the scattering of phonons by including various types of scattering centres in the material (nanoparticles, impurities, etc). Here we take another approach and demonstrate that one can also use coherent band structure effects to control phonon thermal conductance, with the help of periodically nanostructured phononic crystals. We perform the experiments at low temperatures below 1 K, which not only leads to negligible bulk phonon scattering, but also increases the wavelength of the dominant thermal phonons by more than two orders of magnitude compared to room temperature. Thus, phononic crystals with lattice constants ≥1 μm are shown to strongly reduce the thermal conduction. The observed effect is in quantitative agreement with the theoretical calculation presented, which accurately determined the ballistic thermal conductance in a phononic crystal device.

Method and device for predicting wavelength dependent radiation influences in thermal systems

DOEpatents

Kee, Robert J.; Ting, Aili

1996-01-01

A method and apparatus for predicting the spectral (wavelength-dependent) radiation transport in thermal systems including interaction by the radiation with partially transmitting medium. The predicted model of the thermal system is used to design and control the thermal system. The predictions are well suited to be implemented in design and control of rapid thermal processing (RTP) reactors. The method involves generating a spectral thermal radiation transport model of an RTP reactor. The method also involves specifying a desired wafer time dependent temperature profile. The method further involves calculating an inverse of the generated model using the desired wafer time dependent temperature to determine heating element parameters required to produce the desired profile. The method also involves controlling the heating elements of the RTP reactor in accordance with the heating element parameters to heat the wafer in accordance with the desired profile.

The performance of residential micro-cogeneration coupled with thermal and electrical storage

NASA Astrophysics Data System (ADS)

Kopf, John

Over 80% of residential secondary energy consumption in Canada and Ontario is used for space and water heating. The peak electricity demands resulting from residential energy consumption increase the reliance on fossil-fuel generation stations. Distributed energy resources can help to decrease the reliance on central generation stations. Presently, distributed energy resources such as solar photovoltaic, wind and bio-mass generation are subsidized in Ontario. Micro-cogeneration is an emerging technology that can be implemented as a distributed energy resource within residential or commercial buildings. Micro-cogeneration has the potential to reduce a building's energy consumption by simultaneously generating thermal and electrical power on-site. The coupling of a micro-cogeneration device with electrical storage can improve the system's ability to reduce peak electricity demands. The performance potential of micro-cogeneration devices has yet to be fully realized. This research addresses the performance of a residential micro-cogeneration device and it's ability to meet peak occupant electrical loads when coupled with electrical storage. An integrated building energy model was developed of a residential micro-cogeneration system: the house, the micro-cogeneration device, all balance of plant and space heating components, a thermal storage device, an electrical storage device, as well as the occupant electrical and hot water demands. This model simulated the performance of a micro-cogeneration device coupled to an electrical storage system within a Canadian household. A customized controller was created in ESP-r to examine the impact of various system control strategies. The economic performance of the system was assessed from the perspective of a local energy distribution company and an end-user under hypothetical electricity export purchase price scenarios. It was found that with certain control strategies the micro-cogeneration system was able to improve the economic performance for both the end user and local distribution company.

Review on Variable Emissivity Materials and Devices Based on Smart Chromism

NASA Astrophysics Data System (ADS)

Lang, FengPei; Wang, Hao; Zhang, ShengJun; Liu, JingBing; Yan, Hui

2018-01-01

Variable emissivity material (VEM) can dynamically vary its emissivity and infrared radiation under certain conditions, which may find potential applications in infrared stealth/camouflage, solar thermal collector, spacecraft thermal control, and smart energy-saving windows. In this paper, the variable emissivity materials and devices based on electrochromism and thermochromism are introduced. The basic principle and present status of the research in these fields are overviewed. Four kinds of representative VEMs are extensively summarized, which are tungsten trioxides (WO3), conducting polymers (CPs), perovskite oxides (A_{1-{x}}B_{{x}}MO3), and vanadium dioxide (VO2). Finally, specific issues confronted with electrochromic and thermochromic materials and devices are prospected.

Liquid rocket engine combustion stabilization devices

NASA Technical Reports Server (NTRS)

1974-01-01

Combustion instability, which results from a coupling of the combustion process and the fluid dynamics of the engine system, was investigated. The design of devices which reduce coupling (combustion chamber baffles) and devices which increase damping (acoustic absorbers) are described. Included in the discussion are design criteria and recommended practices, structural and mechanical design, thermal control, baffle geometry, baffle/engine interactions, acoustic damping analysis, and absorber configurations.

Component technology for space power systems

NASA Technical Reports Server (NTRS)

Finke, R.

1982-01-01

The Lewis/OAST program for the development of Component Technology for Space Power Systems is described. The program is divided into five generic areas: semiconductor devices (transistors, thyristors, and diodes); conductors (materials and transmission lines); dielectrics; magnetic devices; and thermal control devices. Examples of progress in each of the five areas is discussed. Bipolar power transistors up to 1000 V at 100 A with a gain of 10 and a 0.5 mu sec rise and fall time are presented. A new class of semiconductor devices with a possibility of switching 1000 000 V is described. Several 100 kW rotary power transformer designs and a 25 kW, 20 kHz transformer weighting 3.2 kg have been developed. Progress on the creation of diamond-like films for thermal devices and intercalated carbon fibers with the strength of steel and the conductivity of copper at one third the mass of copper is presented.

Agricultural Electricity. Electric Controls. Student Manual. Report No. 820/20.

ERIC Educational Resources Information Center

Benson, Robert T.

Addressed to the student, this manual presents terms, abbreviations, and symbols used in discussing manual or automatic control of the flow of electric current. Diagrams accompany discussion of the following types of control devices and principles of operation: Heat sensitive controls (thermostats, thermal relays), light sensitive controls…

A multiple functional connector for high-resolution optical satellites

NASA Astrophysics Data System (ADS)

She, Fengke; Zheng, Gangtie

2017-11-01

For earth observation satellites, perturbations from actuators, such as CMGs and momentum wheels, and thermal loadings from support structures often have significant impact on the image quality of an optical. Therefore, vibration isolators and thermal deformation releasing devices nowadays often become important parts of an image satellite. However, all these devices will weak the connection stiffness between the optical instrument and the satellite bus structure. This will cause concern of the attitude control system design for worrying about possible negative effect on the attitude control. Therefore, a connection design satisfying all three requirements is a challenge of advanced image satellites. Chinese scientists have proposed a large aperture high-resolution satellite for earth observation. To meet all these requirements and ensure image quality, specified multiple function connectors are designed to meet these challenging requirements, which are: isolating vibration, releasing thermal deformation and ensuring whole satellite dynamic properties [1]. In this paper, a parallel spring guide flexure is developed for both vibration isolation and thermal deformation releasing. The stiffness of the flexure is designed to meet the vibration isolation requirement. To attenuate vibration, and more importantly to satisfy the stability requirement of the attitude control system, metal damping, which has many merits for space applications, are applied in this connecter to provide a high damping ratio and nonlinear stiffness. The capability of the connecter for vibration isolation and attenuation is validated through numerical simulation and experiments. Connecter parameter optimization is also conducted to meet both requirements of thermal deformation releasing and attitude control. Analysis results show that the in-orbit attitude control requirement is satisfied while the thermal releasing performance is optimized. The design methods and analysis results are also provided in the present paper.

An experimental study on the performance of closed loop pulsating heat pipe (CLPHP) with methanol as a working fluid

NASA Astrophysics Data System (ADS)

Rahman, Md. Lutfor; Nourin, Farah Nazifa; Salsabil, Zaimaa; Yasmin, Nusrat; Ali, Mohammad

2016-07-01

Thermal control is an important topic for thermal management of small electrical and electronic devices. Closed loop pulsating heat pipe (CLPHP) arises as the best solution for thermal control. The aim of this experimental study is to search a CLPHP of better thermal performance for cooling different electrical and electronic devices. In this experiment, methanol is used as working fluid. The effect of using methanol as a working fluid is studied on thermal performance in different filling ratios and angles of inclination. A copper capillary tube is used where the inner diameter is 2mm,outer diameter is 2.5mm and 250mm long. The CLPHP has 8 loops where the evaporation section is 50mm, adiabatic section is 120mm and condensation section is 80mm. The experiment is done using FR of 40%-70% with 10% of interval and angles of inclination 0° (vertical), 30°, 45°, 60° varying heat input. The results are compared on the basis of evaporator temperature, condenser temperature and their differences, thermal resistance, heat transfer co-efficient, power input and pulsating time. The results demonstrate the effect of methanol in different filling ratios and angles of inclination. M ethanol shows better performance at 30° inclination with 40% FR.

Interior and exterior ballistics coupled optimization with constraints of attitude control and mechanical-thermal conditions

NASA Astrophysics Data System (ADS)

Liang, Xin-xin; Zhang, Nai-min; Zhang, Yan

2016-07-01

For solid launch vehicle performance promotion, a modeling method of interior and exterior ballistics associated optimization with constraints of attitude control and mechanical-thermal condition is proposed. Firstly, the interior and external ballistic models of the solid launch vehicle are established, and the attitude control model of the high wind area and the stage of the separation is presented, and the load calculation model of the drag reduction device is presented, and thermal condition calculation model of flight is presented. Secondly, the optimization model is established to optimize the range, which has internal and external ballistic design parameters as variables selected by sensitivity analysis, and has attitude control and mechanical-thermal conditions as constraints. Finally, the method is applied to the optimal design of a three stage solid launch vehicle simulation with differential evolution algorithm. Simulation results are shown that range capability is improved by 10.8%, and both attitude control and mechanical-thermal conditions are satisfied.

Semi-transparent solar energy thermal storage device

DOEpatents

McClelland, John F.

1986-04-08

A visually transmitting solar energy absorbing thermal storage module includes a thermal storage liquid containment chamber defined by an interior solar absorber panel, an exterior transparent panel having a heat mirror surface substantially covering the exterior surface thereof and associated top, bottom and side walls. Evaporation of the thermal storage liquid is controlled by a low vapor pressure liquid layer that floats on and seals the top surface of the liquid. Porous filter plugs are placed in filler holes of the module. An algicide and a chelating compound are added to the liquid to control biological and chemical activity while retaining visual clarity. A plurality of modules may be supported in stacked relation by a support frame to form a thermal storage wall structure.

Semi-transparent solar energy thermal storage device

DOEpatents

McClelland, John F.

1985-06-18

A visually transmitting solar energy absorbing thermal storage module includes a thermal storage liquid containment chamber defined by an interior solar absorber panel, an exterior transparent panel having a heat mirror surface substantially covering the exterior surface thereof and associated top, bottom and side walls, Evaporation of the thermal storage liquid is controlled by a low vapor pressure liquid layer that floats on and seals the top surface of the liquid. Porous filter plugs are placed in filler holes of the module. An algicide and a chelating compound are added to the liquid to control biological and chemical activity while retaining visual clarity. A plurality of modules may be supported in stacked relation by a support frame to form a thermal storage wall structure.

A Theoretical Review on Interfacial Thermal Transport at the Nanoscale.

PubMed

Zhang, Ping; Yuan, Peng; Jiang, Xiong; Zhai, Siping; Zeng, Jianhua; Xian, Yaoqi; Qin, Hongbo; Yang, Daoguo

2018-01-01

With the development of energy science and electronic technology, interfacial thermal transport has become a key issue for nanoelectronics, nanocomposites, energy transmission, and conservation, etc. The application of thermal interfacial materials and other physical methods can reliably improve the contact between joined surfaces and enhance interfacial thermal transport at the macroscale. With the growing importance of thermal management in micro/nanoscale devices, controlling and tuning the interfacial thermal resistance (ITR) at the nanoscale is an urgent task. This Review examines nanoscale interfacial thermal transport mainly from a theoretical perspective. Traditional theoretical models, multiscale models, and atomistic methodologies for predicting ITR are introduced. Based on the analysis and summary of the factors that influence ITR, new methods to control and reduce ITR at the nanoscale are described in detail. Furthermore, the challenges facing interfacial thermal management and the further progress required in this field are discussed. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Photodetectors with passive thermal radiation control

DOEpatents

Lin, Shawn-Yu; Fleming, James G.; Dodson, Brian W.

2001-10-02

A new class of photodetectors which include means for passive shielding against undesired thermal radiation is disclosed. Such devices can substitute in applications currently requiring cooled optical sensors, such as IR detection and imaging. This description is included for purposes of searching, and is not intended to limit or otherwise influence the interpretation of the present invention.

Cryogenic Two-Phase Flight Experiment: Results overview

NASA Technical Reports Server (NTRS)

Swanson, T.; Buchko, M.; Brennan, P.; Bello, M.; Stoyanof, M.

1995-01-01

This paper focuses on the flight results of the Cryogenic Two-Phase Flight Experiment (CRYOTP), which was a Hitchhiker based experiment that flew on the space shuttle Columbia in March of 1994 (STS-62). CRYOTP tested two new technologies for advanced cryogenic thermal control; the Space Heat Pipe (SHP), which was a constant conductance cryogenic heat pipe, and the Brilliant Eyes Thermal Storage Unit (BETSU), which was a cryogenic phase-change thermal storage device. These two devices were tested independently during the mission. Analysis of the flight data indicated that the SHP was unable to start in either of two attempts, for reasons related to the fluid charge, parasitic heat leaks, and cryocooler capacity. The BETSU test article was successfully operated with more than 250 hours of on-orbit testing including several cooldown cycles and 56 freeze/thaw cycles. Some degradation was observed with the five tactical cryocoolers used as thermal sinks, and one of the cryocoolers failed completely after 331 hours of operation. Post-flight analysis indicated that this problem was most likely due to failure of an electrical controller internal to the unit.

Phase-tunable temperature amplifier

NASA Astrophysics Data System (ADS)

Paolucci, F.; Marchegiani, G.; Strambini, E.; Giazotto, F.

2017-06-01

Coherent caloritronics, the thermal counterpart of coherent electronics, has drawn growing attention since the discovery of heat interference in 2012. Thermal interferometers, diodes, transistors and nano-valves have been theoretically proposed and experimentally demonstrated by exploiting the quantum phase difference between two superconductors coupled through a Josephson junction. So far, the quantum-phase modulator has been realized in the form of a superconducting quantum interference device (SQUID) or a superconducting quantum interference proximity transistor (SQUIPT). Thence, an external magnetic field is necessary in order to manipulate the heat transport. Here, we theoretically propose the first on-chip fully thermal caloritronic device: the phase-tunable temperature amplifier (PTA). Taking advantage of a recently discovered thermoelectric effect in spin-split superconductors coupled to a spin-polarized system, we generate the magnetic flux controlling the transport through a temperature-biased SQUIPT by applying a temperature gradient. We simulate the behavior of the device and define a number of figures of merit in full analogy with voltage amplifiers. Notably, our architecture ensures almost infinite input thermal impedance, maximum gain of about 11 and efficiency reaching the 95%. This concept paves the way for applications in radiation sensing, thermal logics and quantum information.

Thermal Integration of a Liquid Acquisition Device into a Cryogenic Feed System

NASA Technical Reports Server (NTRS)

Hastings, L. J.; Bolshinskiy, L. G.; Schunk, R. G.; Martin, A. K.; Eskridge, R. H.; Frenkel, A.; Grayson, G.; Pendleton, M. L.

2011-01-01

Primary objectives of this effort were to define the following: (1) Approaches for quantification of the accumulation of thermal energy within a capillary screen liquid acquisition device (LAD) for a lunar lander upper stage during periods of up to 210 days on the lunar surface, (2) techniques for mitigating heat entrapment, and (3) perform initial testing, data evaluation. The technical effort was divided into the following categories: (1) Detailed thermal modeling of the LAD/feed system interactions using both COMSOL computational fluid device and standard codes, (2) FLOW-3D modeling of bulk liquid to provide interfacing conditions for the LAD thermal modeling, (3) condensation conditioning of capillary screens to stabilize surface tension retention capability, and (4) subscale testing of an integrated LAD/feed system. Substantial progress was achieved in the following technical areas: (1) Thermal modeling and experimental approaches for evaluating integrated cryogen LAD/feed systems, at both the system and component levels, (2) reduced gravity pressure control analyses, (3) analytical modeling and testing for capillary screen conditioning using condensation and wicking, and (4) development of rapid turnaround testing techniques for evaluating LAD/feed system thermal and fluid integration. A comprehensive effort, participants included a diverse cross section of representatives from academia, contractors, and multiple Marshall Space Flight Center organizations.

Micro-Structured Two-Component 3D Metamaterials with Negative Thermal-Expansion Coefficient from Positive Constituents

PubMed Central

Qu, Jingyuan; Kadic, Muamer; Naber, Andreas; Wegener, Martin

2017-01-01

Controlling the thermal expansion of materials is of great technological importance. Uncontrolled thermal expansion can lead to failure or irreversible destruction of structures and devices. In ordinary crystals, thermal expansion is governed by the asymmetry of the microscopic binding potential, which cannot be adjusted easily. In artificial crystals called metamaterials, thermal expansion can be controlled by structure. Here, following previous theoretical work, we fabricate three-dimensional (3D) two-component polymer micro-lattices by using gray-tone laser lithography. We perform cross-correlation analysis of optical microscopy images taken at different sample temperatures. The derived displacement-vector field reveals that the thermal expansion and resulting bending of the bi-material beams leads to a rotation of the 3D chiral crosses arranged onto a 3D checkerboard pattern within one metamaterial unit cell. These rotations can compensate the expansion of the all positive constituents, leading to an effectively near-zero thermal length-expansion coefficient, or over-compensate the expansion, leading to an effectively negative thermal length-expansion coefficient. This evidences a striking level of thermal-expansion control. PMID:28079161

21 CFR 870.5900 - Thermal regulating system.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Thermal regulating system. 870.5900 Section 870...) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Therapeutic Devices § 870.5900 Thermal regulating system. (a) Identification. A thermal regulating system is an external system consisting of a device that...

21 CFR 870.5900 - Thermal regulating system.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Thermal regulating system. 870.5900 Section 870...) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Therapeutic Devices § 870.5900 Thermal regulating system. (a) Identification. A thermal regulating system is an external system consisting of a device that...

21 CFR 870.5900 - Thermal regulating system.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Thermal regulating system. 870.5900 Section 870...) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Therapeutic Devices § 870.5900 Thermal regulating system. (a) Identification. A thermal regulating system is an external system consisting of a device that...

21 CFR 870.5900 - Thermal regulating system.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Thermal regulating system. 870.5900 Section 870...) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Therapeutic Devices § 870.5900 Thermal regulating system. (a) Identification. A thermal regulating system is an external system consisting of a device that...

Thermally responsive polymer electrolytes for inherently safe electrochemical energy storage

NASA Astrophysics Data System (ADS)

Kelly, Jesse C.

Electrochemical double layer capacitors (EDLCs), supercapacitors and Li-ion batteries have emerged as premier candidates to meet the rising demands in energy storage; however, such systems are limited by thermal hazards, thermal runaway, fires and explosions, all of which become increasingly more dangerous in large-format devices. To prevent such scenarios, thermally-responsive polymer electrolytes (RPEs) that alter properties in electrochemical energy storage devices were designed and tested. These RPEs will be used to limit or halt device operation when temperatures increase beyond a predetermined threshold, therefore limiting further heating. The development of these responsive systems will offer an inherent safety mechanism in electrochemical energy storage devices, while preserving the performance, lifetimes, and versatility that large-format systems require. Initial work focused on the development of a model system that demonstrated the concept of RPEs in an electrochemical device. Aqueous electrolyte solutions of polymers exhibiting properties that change in response to temperature were developed for applications in EDLCs and supercapacitors. These "smart materials" provide a means to control electrochemical systems where polymer phase separation at high temperatures affects electrolyte properties and inhibits device performance. Aqueous RPEs were synthesized using N-isopropylacrylamide, which governs the thermal properties, and fractions of acrylic acid or vinyl sulfonic acids, which provide ions to the solution. The molecular properties of these aqueous RPEs, specifically the ionic composition, were shown to influence the temperature-dependent electrolyte properties and the extent to which these electrolytes control the energy storage characteristics of a supercapacitor device. Materials with high ionic content provided the highest room temperature conductivity and electrochemical activity; however, RPEs with low ionic content provided the highest "on-off" ratio in electrochemical activity at elevated temperatures. Overall, solution pH and conductivity were altered by an order of magnitude and device performance (ability to store charge) decreased by over 70%. After demonstration of a model responsive electrolyte in an aqueous system, ionic liquid (IL) based electrolytes were developed as a means of controlling the electrochemical performance in the non-aqueous environments that batteries, specifically Li-ion, require. Here, two systems were developed: (1) an electrolyte comprising poly(ethylene oxide) (PEO), the IL, [EMIM][BF4], and a lithium salt and (2) an electrolyte comprising poly(benzyl methacrylate) (PBzMA), the IL, [EMIM][TFSI], and a lithium salt. In each system, the polymer-IL phase separation inhibited device operation at elevated temperatures. For the PEO/IL electrolyte, the thermally induced liquid-liquid phase separation was shown to decrease the ionic conductivity, thereby affecting the concentration of ions at the electrode. Additionally, an increasing charge transfer resistance associated with the phase separated polymer coating the porous electrode was shown to limit electrochemical activity significantly. For the PBzMA/IL electrolyte, the solid-liquid phase separation did not show a change in conductivity, but did cause a drastic increase in charge transfer resistance, effectively shutting off Li-ion battery operation at high temperatures. Such responsive mixtures provide a transformative approach to regulating electrochemical processes, which is necessary to achieve inherently safe operation in large format energy storage with EDLCs, supercapacitors and Li-ion batteries.

Evaporation on/in Capillary Structures of High Heat Flux Two-Phase Devices

NASA Technical Reports Server (NTRS)

Faghri, Amir; Khrustalev, Dmitry

1996-01-01

Two-phase devices (heat pipes, capillary pumped loops, loop heat pipes, and evaporators) have become recognized as key elements in thermal control systems of space platforms. Capillary and porous structures are necessary and widely used in these devices, especially in high heat flux and zero-g applications, to provide fluid transport and enhanced heat transfer during vaporization and condensation. However, some unexpected critical phenomena, such as dryout in long heat pipe evaporators and high thermal resistance of loop heat pipe evaporators with high heat fluxes, are possible and have been encountered in the use of two-phase devices in the low gravity environment. Therefore, a detailed fundamental investigation is proposed to better understand the fluid behavior in capillary-porous structures during vaporization at high heat fluxes. The present paper addresses some theoretical aspects of this investigation.

Two Decades of Negative Thermal Expansion Research: Where Do We Stand?

PubMed Central

Lind, Cora

2012-01-01

Negative thermal expansion (NTE) materials have become a rapidly growing area of research over the past two decades. The initial discovery of materials displaying NTE over a large temperature range, combined with elucidation of the mechanism behind this unusual property, was followed by predictions that these materials will find use in various applications through controlled thermal expansion composites. While some patents have been filed and devices built, a number of obstacles have prevented the widespread implementation of NTE materials to date. This paper reviews NTE materials that contract due to transverse atomic vibrations, their potential for use in controlled thermal expansion composites, and known problems that could interfere with such applications. PMID:28817027

Two-dimensional thermography image retrieval from zig-zag scanned data with TZ-SCAN

NASA Astrophysics Data System (ADS)

Okumura, Hiroshi; Yamasaki, Ryohei; Arai, Kohei

2008-10-01

TZ-SCAN is a simple and low cost thermal imaging device which consists of a single point radiation thermometer on a tripod with a pan-tilt rotator, a DC motor controller board with a USB interface, and a laptop computer for rotator control, data acquisition, and data processing. TZ-SCAN acquires a series of zig-zag scanned data and stores the data as CSV file. A 2-D thermal distribution image can be retrieved by using the second quefrency peak calculated from TZ-SCAN data. An experiment is conducted to confirm the validity of the thermal retrieval algorithm. The experimental result shows efficient accuracy for 2-D thermal distribution image retrieval.

Organic Light Emitting Devices with Linearly-Graded Mixed Host Architecture

NASA Astrophysics Data System (ADS)

Lee, Sang Min

Organic Light Emitting Devices (OLEDs) with a linearly-graded mixed (LGM) host architecture in the emissive layer (EML) were studied by the application of a newly-developed thermal deposition boat. A new thermal deposition boat, featuring indirect deposition control and fast rate response, was developed in order to make an evaporation coater of high space utilization and to achieve a real time linearly-graded rate control during the device fabrication process. A new design of dual-hole boat, based on the reduced wall resistance of the side hole toward the vapor flow, enabled the indirect deposition rate control with sufficient control accuracy by using the feature of the stable ratio of rates from top and side holes. Minimizing the thermal mass of the body and designing a direct heat transfer with a coil placed inside the boat resulted in the realization of the linearly-graded deposition rate within acceptable deviation range. Thanks to the feature of fast rate response, it was possible to control the linearly-graded rate of each host material during the process and to apply the architecture to some of the fluorescent and phosphorescent OLED devices. The reported efficiency improvement of a fluorescent OLED, based on step-graded junction in the literature, was well reproduced in an OLED with a LGM architecture, demonstrating that charge balance in the emissive layer can be further improved using the LGM architecture. By minimizing the internal energy barrier in the LGM device, a higher EL efficiency was well demonstrated over the uniformly-mixed (UM) host device, where residual internal interfaces were present as additional quenching sites in the EML. Similar effects were observed in blue phosphorescent OLED devices, where the mobility of the hole transport material (HTM) was usually much higher than that of the electron transport material (ETM) such that the recombination zone was more localized at the EML/ETL interface. It was found that the main effect of the LGM host was to shift the recombination zone inside of the EML and away from and ETL interface such that luminance quenching near the interface was much lower compared to the UM host, where the main recombination zone was localized near the interface and so more sensitive to the interface quenching.

High-Temperature Optical Sensor

NASA Technical Reports Server (NTRS)

Adamovsky, Grigory; Juergens, Jeffrey R.; Varga, Donald J.; Floyd, Bertram M.

2010-01-01

A high-temperature optical sensor (see Figure 1) has been developed that can operate at temperatures up to 1,000 C. The sensor development process consists of two parts: packaging of a fiber Bragg grating into a housing that allows a more sturdy thermally stable device, and a technological process to which the device is subjected to in order to meet environmental requirements of several hundred C. This technology uses a newly discovered phenomenon of the formation of thermally stable secondary Bragg gratings in communication-grade fibers at high temperatures to construct robust, optical, high-temperature sensors. Testing and performance evaluation (see Figure 2) of packaged sensors demonstrated operability of the devices at 1,000 C for several hundred hours, and during numerous thermal cycling from 400 to 800 C with different heating rates. The technology significantly extends applicability of optical sensors to high-temperature environments including ground testing of engines, flight propulsion control, thermal protection monitoring of launch vehicles, etc. It may also find applications in such non-aerospace arenas as monitoring of nuclear reactors, furnaces, chemical processes, and other hightemperature environments where other measurement techniques are either unreliable, dangerous, undesirable, or unavailable.

Thermal Control Using Electrochromism

NASA Technical Reports Server (NTRS)

Vaidyanathan, Hari; Rao, Gopalakrishna

1998-01-01

The applicability of a charge balanced electrochromic device to modulate the frequencies in the thermal infra red region is examined in this study. The device consisted of a transparent conductor, WO3 anode, PMMA/LiClO4, electrolyte, V2O5, cathode and transparent conductor. The supporting structure in the device is SnO2 coated glass and the edges are sealed with epoxy to reduce moisture absorption. The performance evaluation comprised of cyclic voltammetric measurements and determination of transmittance at various wavelengths. The device was subjected to anodic and cathodic polarization by sweeping the potential at a rate of 10 mV/sec from -0.8 V to 1.8 V. The current versus voltage profile indicated no reaction between -0.5 and +0.5 V. The device is colored green at 1.8 V with a transmittance of 5% at a wavelength, lambda = 900 nm and colorless at -0.8 V with a transmittance of 74% at X = 500 nm. The optical modulation is limited to 400-1500 nm and there is no activity in the thermal infrared. The switching time is 75 seconds for transmittance to decrease from 74% to 50%. The device yielded reproducible values for transmittance when cycled between colored and bleached states by application of 1.8 V and -0.8 V, respectively.

Thermal Control Using Electrochromism

NASA Technical Reports Server (NTRS)

Vaidyanathan, Hari; Rao, Gopalakrishna

1999-01-01

The applicability of a charge balanced electrochromic device to modulate the frequencies in the thermal infrared region is examined in this study. The device consisted of a transparent conductor, WO3, anode, PMMA/LiClO4 electrolyte, V2O5 cathode and transparent conductor. The supporting structure in the device is SnO2 coated glass and the edges are sealed with epoxy to reduce moisture absorption. The performance evaluation comprised of cyclic voltammetric measurements and determination of transmittance at various wavelengths. The device was subjected to anodic and cathodic polarization by sweeping the potential at a rate of 10 mV/sec from -0.8V to 1.8V. The current versus voltage profile indicated no reaction between -0.5 and +0.5 V. The device is colored green at 1.8 V with a transmittance of 5% at a wavelength, lambda = 900 nm and colorless at -0.8 V with a transmittance of 74% at lambda = 500 nm. The optical modulation is limited to 400-1500 nm and there is no activity in the thermal infrared. The switching time is a function of temperature and time for coloring reaction was slower than the bleaching reaction. The device yielded reproducible values for transmittance when cycled between colored and bleached states by application of 1.8V and -0.8V, respectively.

Thermal Control using Electrochromism

NASA Technical Reports Server (NTRS)

Vaidyanathan, Hari; Rao, Gopalakrishna

1998-01-01

The applicability of a charge balanced electrochromic device to modulate the frequencies in the thermal infrared region is examined in this study. The device consisted of a transparent conductor, WO3 anode, PMMA/LiClO4 electrolyte, V2O5 cathode and transparent conductor. The supporting structure in the device is SnO2 coated glass and the edges are sealed with epoxy to reduce moisture absorption. The performance evaluation comprised of cyclic voltammetric measurements and determination of transmittance at various wavelengths. The device was subjected to anodic and cathodic polarization by sweeping the potential at a rate of 10 mV/sec from -0.8V to 1.8V. The current versus voltage profile indicated no reaction between -0.5 and +0.5 V. The device is colored green at 1.8V with a transmittance of 5% at a wavelength, lambda=900 nm and colorless at -0.8V with a transmittance of 74% at lambda=500 nm. The optical modulation is limited to 400-1500 nm and there is no activity in the thermal infrared. The switching time is 75 seconds for transmittance to decrease from 74% to 50%. The device yielded reproducible values for transmittance when cycled between colored and bleached states by application of 1.8V and -0.8V, respectively.

Photo-response behavior of organic transistors based on thermally annealed semiconducting diketopyrrolopyrrole core

NASA Astrophysics Data System (ADS)

Tarsoly, Gergely; Pyo, Seungmoon

2018-06-01

We report the opto-electrical response of organic field-effect transistors based on a thin-film of a semiconducting diketopyrrolopyrrole (DPP) core, a popular building block for molecular semiconductors, and a polymeric gate dielectric. The thin-film of the DPP core was thermally annealed at different temperatures under N2 atmosphere to investigate the relationship between the annealing temperature and the electrical properties of the device. The results showed that the annealing process induces morphological changes in the thin film, and properly controlling the thermal annealing conditions can enhance the device performance. In addition, we also investigated in detail the photo-response behaviors by analyzing the responsivity (R) of the device with the optimally annealed DPP-core thin film under two light illumination conditions by considering the irradiance absorbed by the thin film instead of the total irradiance of the light source. We found that the proposed model could lead to a light-source-independent description of the photo-response behavior of the device, and which can be used for other applications.

Development of a Microelectromechanical System for Small Satellite Thermal Control

DTIC Science & Technology

2004-05-06

polymer frame or post over a silicon substrate. The membrane should be coated with a high emissivity material. This design was based on the principle...allowing heat conduction to the silicon. While the device was off, both the poor thermal conductivity of the polymer and the gap between membrane and...EnergyThermally Isolating Vacuum and Polymer Heat Conduction (a) (b) Figure 4. Heat conduction and radiation in the on and off states

Electro-opto-thermal addressing bistable and re-addressable display device based on gelator-doped liquid crystals in a poly(N-vinylcarbazole) film-coated liquid crystal cell.

PubMed

Cheng, Ko-Ting; Tang, Yi; Liu, Cheng-Kai

2016-10-03

This paper reports an electro-opto-thermal addressing bistable and re-addressable display device based on gelator-doped liquid crystals (LCs) in a poly(N-vinylcarbazole) film-coated LC cell. The bistability and re-addressability of the devices were achieved through the formation of a rubbery LC/gel mixture at room temperature. The desired patterns were addressed, erased, and re-addressed by controlling the temperature, applied voltage, and UV light illumination. Moreover, grayscales were obtained by adjusting UV light intensity. The initiation, relaxation, rise, and fall times of photoconductive poly(N-vinylcarbazole) via UV light illumination of various intensities were also examined.

Considerations for ex vivo thermal tissue testing exemplified using the fresh porcine longissimus muscle model for endometrial ablation

NASA Astrophysics Data System (ADS)

Fugett, James H.; Bennett, Haydon E.; Shrout, Joshua L.; Coad, James E.

2017-02-01

Expansions in minimally invasive medical devices and technologies with thermal mechanisms of action are continuing to advance the practice of medicine. These expansions have led to an increasing need for appropriate animal models to validate and quantify device performance. The planning of these studies should take into consideration a variety of parameters, including the appropriate animal model (test system - ex vivo or in vivo; species; tissue type), treatment conditions (test conditions), predicate device selection (as appropriate, control article), study timing (Day 0 acute to more than Day 90 chronic survival studies), and methods of tissue analysis (tissue dissection - staining methods). These considerations are discussed and illustrated using the fresh extirpated porcine longissimus muscle model for endometrial ablation.

Fast Conformal Thermal Ablation in the Prostate with Transurethral Multi-Sectored Ultrasound Devices and MR Guidance

NASA Astrophysics Data System (ADS)

Kinsey, Adam M.; Diederich, Chris J.; Nau, William H.; Ross, Anthony B.; Pauly, Kim Butts; Rieke, Viola; Sommer, Graham

2007-05-01

Transurethral ultrasound applicators incorporating an array of multisectored tubular transducers were evaluated in theoretical simulations and in vivo canine prostates under MR guidance as a method for fast, conformal thermal therapy of the prostate. Comprehensive simulations with a biothermal model investigated the effect on lesion creation of sector size, perfusion, treatment time, rectal cooling, prostate target dimensions, and feedback controller parameters (maximum temperature, pilot points at boundary, update times). In vivo canine prostates (n = 4) were treated with trisectored ultrasound transducers (3 mm OD) under MR temperature monitoring to contour the ablation zone (>52 C for 1-2 min) to the boundary of the prostate. Contiguous thermal lesions extended 2 cm in radius from the urethra in less than 15 min and independent sector control simultaneously allowed for conformal treatment in the angular dimension. Experiments investigated sequential translation of the transducer assembly within the catheter for tailoring heat treatments to different partitions in the prostate (base, apex) without changing the initial setup. This treatment method offered greater lesion shape control in three dimensions and slightly lengthened the overall treatment time. The MR temperature images correlated with post-treatment histology and accurately controlled the heating to the target boundary. MR-based control of transurethral ultrasound devices appeared more practical with multisectored transducers compared to rotating curvilinear and planar applicators due to less stringent requirements on spatial and temporal MR parameters. This study demonstrated the applicability of these devices in the prostate for anterior-lateral BPH treatment, and whole gland or quadrant target volumes for cancer treatment.

21 CFR 886.4115 - Thermal cautery unit.

Code of Federal Regulations, 2013 CFR

2013-04-01

...) MEDICAL DEVICES OPHTHALMIC DEVICES Surgical Devices § 886.4115 Thermal cautery unit. (a) Identification. A thermal cautery unit is an AC-powered or battery-powered device intended for use during ocular surgery to... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Thermal cautery unit. 886.4115 Section 886.4115...

21 CFR 886.4115 - Thermal cautery unit.

Code of Federal Regulations, 2012 CFR

2012-04-01

...) MEDICAL DEVICES OPHTHALMIC DEVICES Surgical Devices § 886.4115 Thermal cautery unit. (a) Identification. A thermal cautery unit is an AC-powered or battery-powered device intended for use during ocular surgery to... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Thermal cautery unit. 886.4115 Section 886.4115...

21 CFR 886.4115 - Thermal cautery unit.

Code of Federal Regulations, 2010 CFR

2010-04-01

...) MEDICAL DEVICES OPHTHALMIC DEVICES Surgical Devices § 886.4115 Thermal cautery unit. (a) Identification. A thermal cautery unit is an AC-powered or battery-powered device intended for use during ocular surgery to... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Thermal cautery unit. 886.4115 Section 886.4115...

21 CFR 886.4115 - Thermal cautery unit.

Code of Federal Regulations, 2011 CFR

2011-04-01

...) MEDICAL DEVICES OPHTHALMIC DEVICES Surgical Devices § 886.4115 Thermal cautery unit. (a) Identification. A thermal cautery unit is an AC-powered or battery-powered device intended for use during ocular surgery to... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Thermal cautery unit. 886.4115 Section 886.4115...

21 CFR 886.4115 - Thermal cautery unit.

Code of Federal Regulations, 2014 CFR

2014-04-01

...) MEDICAL DEVICES OPHTHALMIC DEVICES Surgical Devices § 886.4115 Thermal cautery unit. (a) Identification. A thermal cautery unit is an AC-powered or battery-powered device intended for use during ocular surgery to... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Thermal cautery unit. 886.4115 Section 886.4115...

Combustion Device Failures During Space Shuttle Main Engine Development

NASA Technical Reports Server (NTRS)

Goetz, Otto K.; Monk, Jan C.

2005-01-01

Major Causes: Limited Initial Materials Properties. Limited Structural Models - especially fatigue. Limited Thermal Models. Limited Aerodynamic Models. Human Errors. Limited Component Test. High Pressure. Complicated Control.

Doping-tunable thermal emission from plasmon polaritons in semiconductor epsilon-near-zero thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jun, Young Chul; Luk, Ting S.; Robert Ellis, A.

2014-09-29

Here, we utilize the unique dispersion properties of leaky plasmon polaritons in epsilon-near-zero (ENZ) thin films to demonstrate thermal radiation control. Owing to its highly flat dispersion above the light line, a thermally excited leaky wave at the ENZ frequency out-couples into free space without any scattering structures, resulting in a narrowband, wide-angle, p-polarized thermal emission spectrum. We demonstrate this idea by measuring angle- and polarization-resolved thermal emission spectra from a single layer of unpatterned, doped semiconductors with deep-subwavelength film thickness (d/λ0 ~ 6 ×10 -3, where d is the film thickness and λ0 is the free space wavelength). Wemore » show that this semiconductor ENZ film effectively works as a leaky wave thermal radiation antenna, which generates far-field radiation from a thermally excited mode. The use of semiconductors makes the radiation frequency highly tunable by controlling doping densities and also facilitates device integration with other components. Therefore, this leaky plasmon polariton emission from semiconductor ENZ films provides an avenue for on-chip control of thermal radiation.« less

Magneto-Hydrodynamics Based Microfluidics

PubMed Central

Qian, Shizhi; Bau, Haim H.

2009-01-01

In microfluidic devices, it is necessary to propel samples and reagents from one part of the device to another, stir fluids, and detect the presence of chemical and biological targets. Given the small size of these devices, the above tasks are far from trivial. Magnetohydrodynamics (MHD) offers an elegant means to control fluid flow in microdevices without a need for mechanical components. In this paper, we review the theory of MHD for low conductivity fluids and describe various applications of MHD such as fluid pumping, flow control in fluidic networks, fluid stirring and mixing, circular liquid chromatography, thermal reactors, and microcoolers. PMID:20046890

40 CFR 63.5994 - How do I conduct tests and procedures for tire production affected sources?

Code of Federal Regulations, 2010 CFR

2010-07-01

... a thermal oxidizer, monitor the firebox secondary chamber temperature. (ii) If you use a carbon... the carbon bed temperature after each regeneration, and within 15 minutes of completing any cooling cycle. (iii) If you use a control device other than a thermal oxidizer or a regenerative carbon adsorber...

40 CFR 63.6000 - How do I conduct tests and procedures for puncture sealant application affected sources?

Code of Federal Regulations, 2012 CFR

2012-07-01

... thermal oxidizer, monitor the firebox secondary chamber temperature. (ii) If you use a carbon adsorber, monitor the total regeneration stream mass or volumetric flow for each regeneration cycle, and the carbon...) For each control device used other than a thermal oxidizer or a regenerative carbon adsorber, install...

40 CFR 63.5994 - How do I conduct tests and procedures for tire production affected sources?

Code of Federal Regulations, 2012 CFR

2012-07-01

... a thermal oxidizer, monitor the firebox secondary chamber temperature. (ii) If you use a carbon... the carbon bed temperature after each regeneration, and within 15 minutes of completing any cooling cycle. (iii) If you use a control device other than a thermal oxidizer or a regenerative carbon adsorber...

40 CFR 63.6000 - How do I conduct tests and procedures for puncture sealant application affected sources?

Code of Federal Regulations, 2014 CFR

2014-07-01

... thermal oxidizer, monitor the firebox secondary chamber temperature. (ii) If you use a carbon adsorber, monitor the total regeneration stream mass or volumetric flow for each regeneration cycle, and the carbon...) For each control device used other than a thermal oxidizer or a regenerative carbon adsorber, install...

40 CFR 63.6000 - How do I conduct tests and procedures for puncture sealant application affected sources?

Code of Federal Regulations, 2013 CFR

2013-07-01

... thermal oxidizer, monitor the firebox secondary chamber temperature. (ii) If you use a carbon adsorber, monitor the total regeneration stream mass or volumetric flow for each regeneration cycle, and the carbon...) For each control device used other than a thermal oxidizer or a regenerative carbon adsorber, install...

Design of a Nanoscale, CMOS-Integrable, Thermal-Guiding Structure for Boolean-Logic and Neuromorphic Computation.

PubMed

Loke, Desmond; Skelton, Jonathan M; Chong, Tow-Chong; Elliott, Stephen R

2016-12-21

One of the requirements for achieving faster CMOS electronics is to mitigate the unacceptably large chip areas required to steer heat away from or, more recently, toward the critical nodes of state-of-the-art devices. Thermal-guiding (TG) structures can efficiently direct heat by "meta-materials" engineering; however, some key aspects of the behavior of these systems are not fully understood. Here, we demonstrate control of the thermal-diffusion properties of TG structures by using nanometer-scale, CMOS-integrable, graphene-on-silica stacked materials through finite-element-methods simulations. It has been shown that it is possible to implement novel, controllable, thermally based Boolean-logic and spike-timing-dependent plasticity operations for advanced (neuromorphic) computing applications using such thermal-guide architectures.

Thermal expansion as a precision actuator

NASA Astrophysics Data System (ADS)

Miller, Chris; Montgomery, David; Black, Martin; Schnetler, Hermine

2016-07-01

The UK ATC has developed a novel thermal actuator design as part of an OPTICON project focusing on the development of a Freeform Active Mirror Element (FAME). The actuator uses the well understood concept of thermal expansion to generate the required force and displacement. As heat is applied to the actuator material it expands linearly. A resistance temperature device (RTD) is embedded in the centre of the actuator and is used both as a heater and a sensor. The RTD temperature is controlled electronically by injecting a varying amount of current into the device whilst measuring the voltage across it. Temperature control of the RTD has been achieved to within 0.01°C. A 3D printed version of the actuator is currently being used at the ATC to deform a mirror but it has several advantages that may make it suitable to other applications. The actuator is cheap to produce whilst obtaining a high accuracy and repeatability. The actuator design would be suitable for applications requiring large numbers of actuators with high precision.

Methods of Measurement for Semiconductor Materials, Process Control, and Devices

NASA Technical Reports Server (NTRS)

Bullis, W. M. (Editor)

1973-01-01

The development of methods of measurement for semiconductor materials, process control, and devices is reported. Significant accomplishments include: (1) Completion of an initial identification of the more important problems in process control for integrated circuit fabrication and assembly; (2) preparations for making silicon bulk resistivity wafer standards available to the industry; and (3) establishment of the relationship between carrier mobility and impurity density in silicon. Work is continuing on measurement of resistivity of semiconductor crystals; characterization of generation-recombination-trapping centers, including gold, in silicon; evaluation of wire bonds and die attachment; study of scanning electron microscopy for wafer inspection and test; measurement of thermal properties of semiconductor devices; determination of S-parameters and delay time in junction devices; and characterization of noise and conversion loss of microwave detector diodes.

Refractometric sensitivity and thermal stabilization of fluorescent core microcapillary sensors: theory and experiment.

PubMed

Lane, S; Marsiglio, F; Zhi, Y; Meldrum, A

2015-02-20

Fluorescent-core microcapillaries (FCMs) present a robust basis for the application of optical whispering gallery modes toward refractometric sensing. An important question concerns whether these devices can be rendered insensitive to local temperature fluctuations, which may otherwise limit their refractometric detection limits, mainly as a result of thermorefractive effects. Here, we first use a standard cylindrical cavity formalism to develop the refractometric and thermally limited detection limits for the FCM structure. We then measure the thermal response of a real device with different analytes in the channel and compare the result to the theory. Good stability against temperature fluctuations was obtained for an ethanol solvent, with a near-zero observed thermal shift for the transverse magnetic modes. Similarly good results could in principle be obtained for any other solvent (e.g., water), if the thickness of the fluorescent layer can be sufficiently well controlled.

P91-1 ARGOS spacecraft thermal control

NASA Astrophysics Data System (ADS)

Sadunas, Jonas; Baginski, Ben; McCarthy, Daniel

1993-07-01

The P91-1, or ARGOS, is a Department of Defense funded (DOD) Space Test Program (STP) satellite managed by the Space and Missile Systems Center Space and Small Launch Vehicle Programs Office (SMC/CUL). Rockwell International Space Systems Division is the space vehicle prime contractor. The P91-1 mission is to fly a suite of eight experiments in a 450 nautical mile sun-synchronous orbit dedicated to three dimensional UV imaging of the ionosphere, X-ray source mapping, navigation, space debris characterization, performance characterization of high temperature super conductivity RF devices, and on orbit demonstration of an electrical propulsion system. The primary purpose of this paper is to acquaint the thermal control community, and potential future follow on mission users, with the thermal control characteristics of the spacecraft, experiment/SV thermal integration aspects, and test verification plans.

Hydrogen generation systems utilizing sodium silicide and sodium silica gel materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wallace, Andrew P.; Melack, John M.; Lefenfeld, Michael

Systems, devices, and methods combine reactant materials and aqueous solutions to generate hydrogen. The reactant materials can sodium silicide or sodium silica gel. The hydrogen generation devices are used in fuels cells and other industrial applications. One system combines cooling, pumping, water storage, and other devices to sense and control reactions between reactant materials and aqueous solutions to generate hydrogen. Multiple inlets of varied placement geometries deliver aqueous solution to the reaction. The reactant materials and aqueous solution are churned to control the state of the reaction. The aqueous solution can be recycled and returned to the reaction. One systemmore » operates over a range of temperatures and pressures and includes a hydrogen separator, a heat removal mechanism, and state of reaction control devices. The systems, devices, and methods of generating hydrogen provide thermally stable solids, near-instant reaction with the aqueous solutions, and a non-toxic liquid by-product.« less

Hydrogen generation systems utilizing sodium silicide and sodium silica gel materials

DOEpatents

Wallace, Andrew P.; Melack, John M.; Lefenfeld, Michael

2015-07-14

Systems, devices, and methods combine reactant materials and aqueous solutions to generate hydrogen. The reactant materials can sodium silicide or sodium silica gel. The hydrogen generation devices are used in fuels cells and other industrial applications. One system combines cooling, pumping, water storage, and other devices to sense and control reactions between reactant materials and aqueous solutions to generate hydrogen. Multiple inlets of varied placement geometries deliver aqueous solution to the reaction. The reactant materials and aqueous solution are churned to control the state of the reaction. The aqueous solution can be recycled and returned to the reaction. One system operates over a range of temperatures and pressures and includes a hydrogen separator, a heat removal mechanism, and state of reaction control devices. The systems, devices, and methods of generating hydrogen provide thermally stable solids, near-instant reaction with the aqueous solutions, and a non-toxic liquid by-product.

Three-dimensional illusion thermal device for location camouflage.

PubMed

Wang, Jing; Bi, Yanqiang; Hou, Quanwen

2017-08-08

Thermal metamaterials, proposed in recent years, provide a new method to manipulate the energy flux in heat transfer, and result in many novel thermal devices. In this paper, an illusion thermal device for location camouflage in 3-dimensional heat conduction regime is proposed based on the transformation thermodynamics. The heat source covered by the device produces a fake signal outside the device, which makes the source look like appearing at another position away from its real position. The parameters required by the device are deduced and the method is validated by simulations. The possible scheme to obtain the thermal conductivities required in the device by composing natural materials is supplied, and the influence of some problems in practical fabrication process of the device on the effect of the camouflage is also discussed.

A New Route toward Systematic Control of Electronic Structures of Graphene and Fabrication of Graphene Field Effect Transistors

DTIC Science & Technology

2016-05-31

Graphene has been proposed as a material for heat dissipation owing to its extremely high thermal conductivity . It was reported that the incorporation...between the thermal conductivity and adhesion forces depending on the number of graphene layers used. Therefore, it is important to optimize growth...during various processes involved in device fabrication and will degrade the electrical and thermal conductivity of graphene due to charge trapping and

An experimental study on the performance of closed loop pulsating heat pipe (CLPHP) with methanol as a working fluid

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rahman, Md. Lutfor; Nourin, Farah Nazifa, E-mail: farahnazifanourin@gmail.com; Salsabil, Zaimaa

Thermal control is an important topic for thermal management of small electrical and electronic devices. Closed loop pulsating heat pipe (CLPHP) arises as the best solution for thermal control. The aim of this experimental study is to search a CLPHP of better thermal performance for cooling different electrical and electronic devices. In this experiment, methanol is used as working fluid. The effect of using methanol as a working fluid is studied on thermal performance in different filling ratios and angles of inclination. A copper capillary tube is used where the inner diameter is 2 mm,outer diameter is 2.5 mm andmore » 250 mm long. The CLPHP has 8 loops where the evaporation section is 50 mm, adiabatic section is 120 mm and condensation section is 80 mm. The experiment is done using FR of 40%-70% with 10% of interval and angles of inclination 0° (vertical), 30°, 45°, 60° varying heat input. The results are compared on the basis of evaporator temperature, condenser temperature and their differences, thermal resistance, heat transfer co-efficient, power input and pulsating time. The results demonstrate the effect of methanol in different filling ratios and angles of inclination. M ethanol shows better performance at 30° inclination with 40% FR.« less

Fabrication of glass-ceramics containing spin-chain compound SrCuO{sub 2} and its high thermal conductivity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Terakado, Nobuaki, E-mail: terakado@laser.apph.tohoku.ac.jp; Watanabe, Kouki; Kawamata, Takayuki

2015-04-06

High thermal conductivity materials are in great demand for heat-flow control and heat dissipation in electronic devices. In this study, we have produced a glass-ceramics that contains spin-chain compound SrCuO{sub 2} and have found that the glass-ceramics yields high thermal conductivity of ∼5 W K{sup −1} m{sup −1} even at room temperature. The glass-ceramics is fabricated through crystallization of inhomogeneous melt-quenched oxides made from SrCO{sub 3}, CuO, Li{sub 2}CO{sub 3}, Ga{sub 2}O{sub 3}, and Al{sub 2}O{sub 3}. Transmission electron microscopy and X-ray and electron diffraction reveal that SrCuO{sub 2} crystallites with a size of 100–200 nm are precipitated in the glass-ceramics. Themore » highness of the thermal conductivity is attributable to two sources: one is elongation of phonon mean free path due to the crystallization of the inhomogeneous structure or structural ordering. The other is emergence of the heat carriers, spinons, in the SrCuO{sub 2}. This highly thermal conductive glass-ceramics is expected to be utilized as base materials for heat-flow control devices.« less

Effect of Back Contact and Rapid Thermal Processing Conditions on Flexible CdTe Device Performance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mahabaduge, Hasitha; Meysing, D. M.; Rance, Will L.

Flexible CdTe solar cells on ultra-thin glass substrates can enable new applications that require high specific power, unique form-factors, and low manufacturing costs. To be successful, these cells must be cost competitive, have high efficiency, and have high reliability. Here we present back contact processing conditions that enabled us to achieve over 16% efficiency on flexible Corning (R) Willow (R) Glass substrates. We used co-evaporated ZnTe:Cu and Au as our back contact and used rapid thermal processing (RTP) to activate the back contact. Both the ZnTe to Cu ratio and the RTP activation temperature provide independent control over the devicemore » performance. We have investigated the influence of various RTP conditions to Cu activation and distribution. Current density-voltage, capacitance-voltage measurements along with device simulations were used to examine the device performance in terms of ZnTe to Cu ratio and rapid thermal activation temperature.« less

Refurbishment and Automation of Thermal Vacuum Facilities at NASA/GSFC

NASA Technical Reports Server (NTRS)

Dunn, Jamie; Gomez, Carlos; Donohue, John; Johnson, Chris; Palmer, John; Sushon, Janet

1999-01-01

The thermal vacuum facilities located at the Goddard Space Flight Center (GSFC) have supported both manned and unmanned space flight since the 1960s. Of the eleven facilities, currently ten of the systems are scheduled for refurbishment or replacement as part of a five-year implementation. Expected return on investment includes the reduction in test schedules, improvements in safety of facility operations, and reduction in the personnel support required for a test. Additionally, GSFC will become a global resource renowned for expertise in thermal engineering, mechanical engineering, and for the automation of thermal vacuum facilities and tests. Automation of the thermal vacuum facilities includes the utilization of Programmable Logic Controllers (PLCs), the use of Supervisory Control and Data Acquisition (SCADA) systems, and the development of a centralized Test Data Management System. These components allow the computer control and automation of mechanical components such as valves and pumps. The project of refurbishment and automation began in 1996 and has resulted in complete computer control of one facility (Facility 281), and the integration of electronically controlled devices and PLCs in multiple others.

Refurbishment and Automation of Thermal Vacuum Facilities at NASA/GSFC

NASA Technical Reports Server (NTRS)

Dunn, Jamie; Gomez, Carlos; Donohue, John; Johnson, Chris; Palmer, John; Sushon, Janet

1998-01-01

The thermal vacuum facilities located at the Goddard Space Flight Center (GSFC) have supported both manned and unmanned space flight since the 1960s. Of the eleven facilities, currently ten of the systems are scheduled for refurbishment or replacement as part of a five-year implementation. Expected return on investment includes the reduction in test schedules, improvements in safety of facility operations, and reduction in the personnel support required for a test. Additionally, GSFC will become a global resource renowned for expertise in thermal engineering, mechanical engineering, and for the automation of thermal vacuum facilities and tests. Automation of the thermal vacuum facilities includes the utilization of Programmable Logic Controllers (PLCs), the use of Supervisory Control and Data Acquisition (SCADA) systems, and the development of a centralized Test Data Management System. These components allow the computer control and automation of mechanical components such as valves and pumps. The project of refurbishment and automation began in 1996 and has resulted in complete computer control of one facility (Facility 281), and the integration of electronically controlled devices and PLCs in multiple others.

Method and Apparatus for the Portable Identification Of Material Thickness And Defects Along Uneven Surfaces Using Spatially Controlled Heat Application

NASA Technical Reports Server (NTRS)

Reilly, Thomas L. (Inventor); Jacobstein, A. Ronald (Inventor); Cramer, K. Elliott (Inventor)

2006-01-01

A method and apparatus for testing a material such as the water-wall tubes in boilers includes the use of a portable thermal line heater having radiation shields to control the amount of thermal radiation that reaches a thermal imager. A procedure corrects for variations in the initial temperature of the material being inspected. A method of calibrating the testing device to determine an equation relating thickness of the material to temperatures created by the thermal line heater uses empirical data derived from tests performed on test specimens for each material type, geometry, density, specific heat, speed at which the line heater is moved across the material and heat intensity.

A Thermal and Electrical Analysis of Power Semiconductor Devices

NASA Technical Reports Server (NTRS)

Vafai, Kambiz

1997-01-01

The state-of-art power semiconductor devices require a thorough understanding of the thermal behavior for these devices. Traditional thermal analysis have (1) failed to account for the thermo-electrical interaction which is significant for power semiconductor devices operating at high temperature, and (2) failed to account for the thermal interactions among all the levels involved in, from the entire device to the gate micro-structure. Furthermore there is a lack of quantitative studies of the thermal breakdown phenomenon which is one of the major failure mechanisms for power electronics. This research work is directed towards addressing. Using a coupled thermal and electrical simulation, in which the drift-diffusion equations for the semiconductor and the energy equation for temperature are solved simultaneously, the thermo-electrical interactions at the micron scale of various junction structures are thoroughly investigated. The optimization of gate structure designs and doping designs is then addressed. An iterative numerical procedure which incorporates the thermal analysis at the device, chip and junction levels of the power device is proposed for the first time and utilized in a BJT power semiconductor device. In this procedure, interactions of different levels are fully considered. The thermal stability issue is studied both analytically and numerically in this research work in order to understand the mechanism for thermal breakdown.

A Real-Time Thermal Self-Elimination Method for Static Mode Operated Freestanding Piezoresistive Microcantilever-Based Biosensors.

PubMed

Ku, Yu-Fu; Huang, Long-Sun; Yen, Yi-Kuang

2018-02-28

Here, we provide a method and apparatus for real-time compensation of the thermal effect of single free-standing piezoresistive microcantilever-based biosensors. The sensor chip contained an on-chip fixed piezoresistor that served as a temperature sensor, and a multilayer microcantilever with an embedded piezoresistor served as a biomolecular sensor. This method employed the calibrated relationship between the resistance and the temperature of piezoresistors to eliminate the thermal effect on the sensor, including the temperature coefficient of resistance (TCR) and bimorph effect. From experimental results, the method was verified to reduce the signal of thermal effect from 25.6 μV/°C to 0.3 μV/°C, which was approximately two orders of magnitude less than that before the processing of the thermal elimination method. Furthermore, the proposed approach and system successfully demonstrated its effective real-time thermal self-elimination on biomolecular detection without any thermostat device to control the environmental temperature. This method realizes the miniaturization of an overall measurement system of the sensor, which can be used to develop portable medical devices and microarray analysis platforms.

Fabrication of 3D electro-thermal micro actuators in silica glass by femtosecond laser wet etch and microsolidics

NASA Astrophysics Data System (ADS)

Li, Qichao; Shan, Chao; Yang, Qing; Chen, Feng; Bian, Hao; Hou, Xun

2017-02-01

This paper demonstrates a novel electro-thermal micro actuator's design, fabrication and device tests which combine microfluidic technology and microsolidics process. A three-dimensional solenoid microchannel with high aspect ratio is fabricated inside the silica glass by an improved femtosecond laser wet etch (FLWE) technology, and the diameter of the spiral coil is only 200 μm. Molten alloy (Bi/In/Sn/Pb) with high melting point is injected into the three-dimensional solenoid microchannel inside the silica glass , then it solidifys and forms an electro-thermal micro actuator. The device is capable of achieving precise temperature control and quick response, and can also be easily integrated into MEMS, sensors and `lab on a chip' (LOC) platform inside the fused silica substrate.

Graphene Aerogel Templated Fabrication of Phase Change Microspheres as Thermal Buffers in Microelectronic Devices.

PubMed

Wang, Xuchun; Li, Guangyong; Hong, Guo; Guo, Qiang; Zhang, Xuetong

2017-11-29

Phase change materials, changing from solid to liquid and vice versa, are capable of storing and releasing a large amount of thermal energy during the phase change, and thus hold promise for numerous applications including thermal protection of electronic devices. Shaping these materials into microspheres for additional fascinating properties is efficient but challenging. In this regard, a novel phase change microsphere with the design for electrical-regulation and thermal storage/release properties was fabricated via the combination of monodispersed graphene aerogel microsphere (GAM) and phase change paraffin. A programmable method, i.e., coupling ink jetting-liquid marbling-supercritical drying (ILS) techniques, was demonstrated to produce monodispersed graphene aerogel microspheres (GAMs) with precise size-control. The resulting GAMs showed ultralow density, low electrical resistance, and high specific surface area with only ca. 5% diameter variation coefficient, and exhibited promising performance in smart switches. The phase change microspheres were obtained by capillary filling of phase change paraffin inside the GAMs and exhibited excellent properties, such as low electrical resistance, high latent heat, well sphericity, and thermal buffering. Assembling the phase change microsphere into the microcircuit, we found that this tiny device was quite sensitive and could respond to heat as low as 0.027 J.

Transformer-rectifier flux pump using inductive current transfer and thermally controlled Nb(3)Sn cryotrons.

PubMed

Atherton, D L; Davies, R

1979-10-01

Transformer-rectifier flux pumps using thermally switched Nb(3)Sn cryotrons are being investigated as a loss make-up device for the proposed isochorically operated (sealed) superconducting magnets for the Canadian Maglev vehicle. High currents (1000 A) were obtained in an experimental flux pump using inductive current transfer and operating at 2 Hz.

High Precision Piezoelectric Linear Motors for Operations at Cryogenic Temperatures and Vacuum

NASA Technical Reports Server (NTRS)

Wong, D.; Carman, G.; Stam, M.; Bar-Cohen, Y.; Sen, A.; Henry, P.; Bearman, G.; Moacanin, J.

1995-01-01

The Jet Propulsion Laboratory evaluated the use of an electromechanical device for optically positioning a mirror system during the pre-project phase of the Pluto-Fast-Flyby (PFF) mission. The device under consideration was a piezoelectric driven linear motor functionally dependent upon a time varying electric field which induces displacements ranging from submicrons to millimeters with positioning accuracy within nanometers. Using a control package, the mirror system provides image motion compensation and mosaicking capabilities. While this device offers unique advantages, there were concerns pertaining to its operational capabilities for the PFF mission. The issues include irradiation effects and thermal concerns. A literature study indicated that irradiation effects will not significantly impact the linear motor's operational characteristics. On the other hand, thermal concerns necessitated an in depth study.

Energy-Efficient Phase-Change Memory with Graphene as a Thermal Barrier.

PubMed

Ahn, Chiyui; Fong, Scott W; Kim, Yongsung; Lee, Seunghyun; Sood, Aditya; Neumann, Christopher M; Asheghi, Mehdi; Goodson, Kenneth E; Pop, Eric; Wong, H-S Philip

2015-10-14

Phase-change memory (PCM) is an important class of data storage, yet lowering the programming current of individual devices is known to be a significant challenge. Here we improve the energy-efficiency of PCM by placing a graphene layer at the interface between the phase-change material, Ge2Sb2Te5 (GST), and the bottom electrode (W) heater. Graphene-PCM (G-PCM) devices have ∼40% lower RESET current compared to control devices without the graphene. This is attributed to the graphene as an added interfacial thermal resistance which helps confine the generated heat inside the active PCM volume. The G-PCM achieves programming up to 10(5) cycles, and the graphene could further enhance the PCM endurance by limiting atomic migration or material segregation at the bottom electrode interface.

Methods of measurement for semiconductor materials, process control, and devices

NASA Technical Reports Server (NTRS)

Bullis, W. M. (Editor)

1972-01-01

Activities directed toward the development of methods of measurement for semiconductor materials, process control, and devices are described. Topics investigated include: measurements of transistor delay time; application of the infrared response technique to the study of radiation-damaged, lithium-drifted silicon detectors; and identification of a condition that minimizes wire flexure and reduces the failure rate of wire bonds in transistors and integrated circuits under slow thermal cycling conditions. Supplementary data concerning staff, standards committee activities, technical services, and publications are included as appendixes.

Improved Electrophoresis Cell

NASA Technical Reports Server (NTRS)

Rhodes, P. H.; Snyder, R. S.

1982-01-01

Several proposed modifications are expected to improve performance of a continous-flow electrophoresis cell. Changes would allow better control of buffer flow and would increase resolution by suppressing thermal gradients. Improved electrophoresis device would have high resolution and be easy to operate. Improvements would allow better flow control and heat dissipation.

Impact of defects on the electrical transport, optical properties and failure mechanisms of GaN nanowires.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Armstrong, Andrew M.; Aubry, Sylvie; Shaner, Eric Arthur

2010-09-01

We present the results of a three year LDRD project that focused on understanding the impact of defects on the electrical, optical and thermal properties of GaN-based nanowires (NWs). We describe the development and application of a host of experimental techniques to quantify and understand the physics of defects and thermal transport in GaN NWs. We also present the development of analytical models and computational studies of thermal conductivity in GaN NWs. Finally, we present an atomistic model for GaN NW electrical breakdown supported with experimental evidence. GaN-based nanowires are attractive for applications requiring compact, high-current density devices such asmore » ultraviolet laser arrays. Understanding GaN nanowire failure at high-current density is crucial to developing nanowire (NW) devices. Nanowire device failure is likely more complex than thin film due to the prominence of surface effects and enhanced interaction among point defects. Understanding the impact of surfaces and point defects on nanowire thermal and electrical transport is the first step toward rational control and mitigation of device failure mechanisms. However, investigating defects in GaN NWs is extremely challenging because conventional defect spectroscopy techniques are unsuitable for wide-bandgap nanostructures. To understand NW breakdown, the influence of pre-existing and emergent defects during high current stress on NW properties will be investigated. Acute sensitivity of NW thermal conductivity to point-defect density is expected due to the lack of threading dislocation (TD) gettering sites, and enhanced phonon-surface scattering further inhibits thermal transport. Excess defect creation during Joule heating could further degrade thermal conductivity, producing a viscous cycle culminating in catastrophic breakdown. To investigate these issues, a unique combination of electron microscopy, scanning luminescence and photoconductivity implemented at the nanoscale will be used in concert with sophisticated molecular-dynamics calculations of surface and defect-mediated NW thermal transport. This proposal seeks to elucidate long standing material science questions for GaN while addressing issues critical to realizing reliable GaN NW devices.« less

Local probing of thermal energy transfer and conversion processes in VO2 nanostructures

NASA Astrophysics Data System (ADS)

Menges, Fabian

Nanostructures of strongly correlated materials, such as metal-insulator transition (MIT) oxides, enable unusual coupling of charge and heat transport. Hence, they provide an interesting pathway to the development of non-linear thermal devices for active heat flux control. Here, we will report the characterization of local thermal non-equilibrium processes in vanadium dioxide (VO2) thin films and single-crystalline nanobeams. Using a scanning thermal microscope and calorimetric MEMS platforms, we studied the MIT triggered by electrical currents, electrical fields, near-field thermal radiation and thermal conduction. Based on out recently introduced scanning probe thermometry method, which enables direct imaging of local Joule and Peltier effects, we quantified self-heating processes in VO2 memristors using the tip of a resistively heated scanning probe both as local sensor and nanoscopic heat source. Finally, we will report on recent approaches to build radiative thermal switches and oscillators using VO2 nanostructures. We quantified variations of near-field radiative thermal transport between silicon dioxide and VO2 down to nanoscopic gap sizes, and will discuss its implications for the development of phonon polariton based radiative thermal devices. Funding of the Swiss Federal Office of Energy under Grant Agreement No. SI/501093-01 is gratefully acknowledged.

Actuating materials. Voxelated liquid crystal elastomers.

PubMed

Ware, Taylor H; McConney, Michael E; Wie, Jeong Jae; Tondiglia, Vincent P; White, Timothy J

2015-02-27

Dynamic control of shape can bring multifunctionality to devices. Soft materials capable of programmable shape change require localized control of the magnitude and directionality of a mechanical response. We report the preparation of soft, ordered materials referred to as liquid crystal elastomers. The direction of molecular order, known as the director, is written within local volume elements (voxels) as small as 0.0005 cubic millimeters. Locally, the director controls the inherent mechanical response (55% strain) within the material. In monoliths with spatially patterned director, thermal or chemical stimuli transform flat sheets into three-dimensional objects through controlled bending and stretching. The programmable mechanical response of these materials could yield monolithic multifunctional devices or serve as reconfigurable substrates for flexible devices in aerospace, medicine, or consumer goods. Copyright © 2015, American Association for the Advancement of Science.

Baseline experimental investigation of an electrohydrodynamically assisted heat pipe

NASA Technical Reports Server (NTRS)

Duncan, A. B.

1995-01-01

The increases in power demand and associated thermal management requirements of future space programs such as potential Lunar/Mars missions will require enhancing the operating efficiencies of thermal management devices. Currently, the use of electrohydrodynamically (EHD) assisted thermal control devices is under consideration as a potential method of increasing thermal management system capacity. The objectives of the currently described investigation included completing build-up of the EHD-Assisted Heat Pipe Test bed, developing test procedures for an experimental evaluation of the unassisted heat pipe, developing an analytical model capable of predicting the performance limits of the unassisted heat pipe, and obtaining experimental data which would define the performance characteristics of the unassisted heat pipe. The information obtained in the currently proposed study will be used in order to provide extensive comparisons with the EHD-assisted performance observations to be obtained during the continuing investigation of EHD-Assisted heat transfer devices. Through comparisons of the baseline test bed data and the EHD assisted test bed data, accurate insight into the performance enhancing characteristics of EHD augmentation may be obtained. This may lead to optimization, development, and implementation of EHD technology for future space programs.

Ge/IIIV fin field-effect transistor common gate process and numerical simulations

NASA Astrophysics Data System (ADS)

Chen, Bo-Yuan; Chen, Jiann-Lin; Chu, Chun-Lin; Luo, Guang-Li; Lee, Shyong; Chang, Edward Yi

2017-04-01

This study investigates the manufacturing process of thermal atomic layer deposition (ALD) and analyzes its thermal and physical mechanisms. Moreover, experimental observations and computational fluid dynamics (CFD) are both used to investigate the formation and deposition rate of a film for precisely controlling the thickness and structure of the deposited material. First, the design of the TALD system model is analyzed, and then CFD is used to simulate the optimal parameters, such as gas flow and the thermal, pressure, and concentration fields, in the manufacturing process to assist the fabrication of oxide-semiconductors and devices based on them, and to improve their characteristics. In addition, the experiment applies ALD to grow films on Ge and GaAs substrates with three-dimensional (3-D) transistors having high electric performance. The electrical analysis of dielectric properties, leakage current density, and trapped charges for the transistors is conducted by high- and low-frequency measurement instruments to determine the optimal conditions for 3-D device fabrication. It is anticipated that the competitive strength of such devices in the semiconductor industry will be enhanced by the reduction of cost and improvement of device performance through these optimizations.

A temperature control method for shortening thermal cycling time to achieve rapid polymerase chain reaction (PCR) in a disposable polymer microfluidic device

NASA Astrophysics Data System (ADS)

Bu, Minqiang; Perch-Nielsen, Ivan R.; Sørensen, Karen S.; Skov, Julia; Sun, Yi; Duong Bang, Dang; Pedersen, Michael E.; Hansen, Mikkel F.; Wolff, Anders

2013-07-01

We present a temperature control method capable of effectively shortening the thermal cycling time of polymerase chain reaction (PCR) in a disposable polymer microfluidic device with an external heater and a temperature sensor. The method employs optimized temperature overshooting and undershooting steps to achieve a rapid ramping between the temperature steps for DNA denaturation, annealing and extension. The temperature dynamics within the microfluidic PCR chamber was characterized and the overshooting and undershooting parameters were optimized using the temperature-dependent fluorescence signal from Rhodamine B. The method was validated with the PCR amplification of mecA gene (162 bp) from methicillin-resistant Staphylococcus aureus bacterium (MRSA), where the time for 30 cycles was reduced from 50 min (without over- and undershooting) to 20 min.

General theories and features of interfacial thermal transport

NASA Astrophysics Data System (ADS)

Zhou, Hangbo; Zhang, Gang

2018-03-01

A clear understanding and proper control of interfacial thermal transport is important in nanoscale device. In this review, we first discuss the theoretical methods to handle the interfacial thermal transport problem, such as the macroscopic model, molecular dynamics, lattice dynamics and modern quantum transport theories. Then we discuss various effects that can significantly affect the interfacial thermal transport, such as the formation of chemical bonds at interface, defects and interface roughness, strain and substrates, atomic species and mass ratios, structural orientations. Then importantly, we analyze the role of inelastic scatterings at the interface, and discuss its application in thermal rectifications. Finally, the challenges and promising directions are discussed.

Unconventional thermal cloak hiding an object outside the cloak

NASA Astrophysics Data System (ADS)

Gao, Y.; Huang, J. P.

2013-11-01

All the thermal cloaks reported in the literature can be used to thermally hide an object inside the cloak. However, a common limitation of this kind of thermal cloaks is that the cloaked object cannot feel the external heat flow since it is located inside the cloak; thus we call these cloaks “conventional thermal cloaks”. Here we manage to overcome this limitation by exploiting a class of unconventional thermal cloaks that enable the cloaked object to feel the external heat flow. Our finite-element simulations in two dimensions show the desired cloaking effect. The underlying mechanism originates from the complementary effect of thermal metamaterials with negative thermal conductivities. This work suggests a different method to design thermal devices where heat conduction can be controlled at will.

Thermal design concept for a high resolution UV spectrometer

NASA Technical Reports Server (NTRS)

Caruso, P.; Stipandic, E.

1979-01-01

The thermal design concept described has been developed for the High Resolution UV Spectrometer/Polarimeter to be flown on the Solar Maximum Mission. Based on experience gained from a similar Orbiting Solar Observatory mission payload, it has been recognized that initial protection of the optical elements, contamination control, reduction of scattered light, tight bulk temperature, and gradient constraints are key elements that must be accommodated in any thermal control concept for this class of instrument. Salient features of the design include: (1) a telescope door providing contamination protection of an aplanatic Gregorian telescope; (2) a rastering system for the secondary mirror; (3) a unique solar heat absorbing device; (4) heat pipes and special radiators; (5) heaters for active temperature control and optics contamination protection; and (6) high precision platinum resistance thermometers. Viability of the design concept has been established by extensive thermal analysis and some subsystem testing. A summary of analytical and test results is included.

Doping-tunable thermal emission from plasmon polaritons in semiconductor epsilon-near-zero thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jun, Young Chul, E-mail: youngchul.jun@inha.ac.kr; Luk, Ting S., E-mail: tsluk@sandia.gov; Brener, Igal

2014-09-29

We utilize the unique dispersion properties of leaky plasmon polaritons in epsilon-near-zero (ENZ) thin films to demonstrate thermal radiation control. Owing to its highly flat dispersion above the light line, a thermally excited leaky wave at the ENZ frequency out-couples into free space without any scattering structures, resulting in a narrowband, wide-angle, p-polarized thermal emission spectrum. We demonstrate this idea by measuring angle- and polarization-resolved thermal emission spectra from a single layer of unpatterned, doped semiconductors with deep-subwavelength film thickness (d/λ{sub 0} ∼ 6×10{sup −3}, where d is the film thickness and  λ{sub 0} is the free space wavelength). We show thatmore » this semiconductor ENZ film effectively works as a leaky wave thermal radiation antenna, which generates far-field radiation from a thermally excited mode. The use of semiconductors makes the radiation frequency highly tunable by controlling doping densities and also facilitates device integration with other components. Therefore, this leaky plasmon polariton emission from semiconductor ENZ films provides an avenue for on-chip control of thermal radiation.« less

Synthesis of Carbon Dots with Multiple Color Emission by Controlled Graphitization and Surface Functionalization.

PubMed

Miao, Xiang; Qu, Dan; Yang, Dongxue; Nie, Bing; Zhao, Yikang; Fan, Hongyou; Sun, Zaicheng

2018-01-01

Multiple-color-emissive carbon dots (CDots) have potential applications in various fields such as bioimaging, light-emitting devices, and photocatalysis. The majority of the current CDots to date exhibit excitation-wavelength-dependent emissions with their maximum emission limited at the blue-light region. Here, a synthesis of multiple-color-emission CDots by controlled graphitization and surface function is reported. The CDots are synthesized through controlled thermal pyrolysis of citric acid and urea. By regulating the thermal-pyrolysis temperature and ratio of reactants, the maximum emission of the resulting CDots gradually shifts from blue to red light, covering the entire light spectrum. Specifically, the emission position of the CDots can be tuned from 430 to 630 nm through controlling the extent of graphitization and the amount of surface functional groups, COOH. The relative photoluminescence quantum yields of the CDots with blue, green, and red emission reach up to 52.6%, 35.1%, and 12.9%, respectively. Furthermore, it is demonstrated that the CDots can be uniformly dispersed into epoxy resins and be fabricated as transparent CDots/epoxy composites for multiple-color- and white-light-emitting devices. This research opens a door for developing low-cost CDots as alternative phosphors for light-emitting devices. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Thermally modulated nano-trampoline material as smart skin for gas molecular mass detection

NASA Astrophysics Data System (ADS)

Xia, Hua

2012-06-01

Conventional multi-component gas analysis is based either on laser spectroscopy, laser and photoacoustic absorption at specific wavelengths, or on gas chromatography by separating the components of a gas mixture primarily due to boiling point (or vapor pressure) differences. This paper will present a new gas molecular mass detection method based on thermally modulated nano-trampoline material as smart skin for gas molecular mass detection by fiber Bragg grating-based gas sensors. Such a nanomaterial and fiber Bragg grating integrated sensing device has been designed to be operated either at high-energy level (highly thermal strained status) or at low-energy level (low thermal strained status). Thermal energy absorption of gas molecular trigs the sensing device transition from high-thermal-energy status to low-thermal- energy status. Experiment has shown that thermal energy variation due to gas molecular thermal energy absorption is dependent upon the gas molecular mass, and can be detected by fiber Bragg resonant wavelength shift with a linear function from 17 kg/kmol to 32 kg/kmol and a sensitivity of 0.025 kg/kmol for a 5 micron-thick nano-trampoline structure and fiber Bragg grating integrated gas sensing device. The laboratory and field validation data have further demonstrated its fast response characteristics and reliability to be online gas analysis instrument for measuring effective gas molecular mass from single-component gas, binary-component gas mixture, and multi-gas mixture. The potential industrial applications include fouling and surge control for gas charge centrifugal compressor ethylene production, gas purity for hydrogen-cooled generator, gasification for syngas production, gasoline/diesel and natural gas fuel quality monitoring for consumer market.

40 CFR 63.4581 - What definitions apply to this subpart?

Code of Federal Regulations, 2010 CFR

2010-07-01

... National Emission Standards for Hazardous Air Pollutants for Surface Coating of Plastic Parts and Products...). Add-on control means an air pollution control device, such as a thermal oxidizer or carbon adsorber, that reduces pollution in an air stream by destruction or removal before discharge to the atmosphere...

40 CFR 63.4581 - What definitions apply to this subpart?

Code of Federal Regulations, 2011 CFR

2011-07-01

... National Emission Standards for Hazardous Air Pollutants for Surface Coating of Plastic Parts and Products...). Add-on control means an air pollution control device, such as a thermal oxidizer or carbon adsorber, that reduces pollution in an air stream by destruction or removal before discharge to the atmosphere...

Thermal Properties of Microstrain Gauges Used for Protection of Lithium-Ion Cells of Different Designs

NASA Technical Reports Server (NTRS)

Jeevarajan, Judith

2011-01-01

The purpose of this innovation is to use microstrain gauges to monitor minute changes in temperature along with material properties of the metal cans and pouches used in the construction of lithium-ion cells. The sensitivity of the microstrain gauges to extremely small changes in temperatures internal to the cells makes them a valuable asset in controlling the hazards in lithium-ion cells. The test program on lithium-ion cells included various cell configurations, including the pouch type configurations. The thermal properties of microstrain gauges have been found to contribute significantly as safety monitors in lithium-ion cells that are designed even with hard metal cases. Although the metal cans do not undergo changes in material property, even under worst-case unsafe conditions, the small changes in thermal properties observed during charge and discharge of the cell provide an observable change in resistance of the strain gauge. Under abusive or unsafe conditions, the change in the resistance is large. This large change is observed as a significant change in slope, and this can be used to prevent cells from going into a thermal runaway condition. For flexible metal cans or pouch-type lithium-ion cells, combinations of changes in material properties along with thermal changes can be used as an indication for the initiation of an unsafe condition. Lithium-ion cells have a very high energy density, no memory effect, and almost 100-percent efficiency of charge and discharge. However, due to the presence of a flammable electrolyte, along with the very high energy density and the capability of releasing oxygen from the cathode, these cells can go into a hazardous condition of venting, fire, and thermal runaway. Commercial lithium-ion cells have current and voltage monitoring devices that are used to control the charge and discharge of the batteries. Some lithium-ion cells have internal protective devices, but when used in multi-cell configurations, these protective devices either do not protect or are themselves a hazard to the cell due to their limitations. These devices do not help in cases where the cells develop high impedance that suddenly causes them to go into a thermal runaway condition. Temperature monitoring typically helps with tracking the performance of a battery. But normal thermistors or thermal sensors do not provide the accuracy needed for this and cannot track a change in internal cell temperatures until it is too late to stop a thermal runaway.

Lateral heat flow distribution and defect-dependent thermal resistance in an individual silicon nanowire.

PubMed

Lee, Seung-Yong; Lee, Won-Yong; Thong, John T L; Kim, Gil-Sung; Lee, Sang-Kwon

2016-03-18

Studies aiming to significantly improve thermal properties, such as figure-of-merit, of silicon nanowires (SiNW) have focused on diameter reduction and surface or interface roughness control. However, the mechanism underlying thermal conductivity enhancement of roughness controlled NWs remains unclear. Here, we report a significant influence of stacking faults (SFs) on the lateral thermal conductivity of a single SiNW, using a combination of newly developed in situ spatially-resolved thermal resistance experiments and high-resolution transmission electron microscopy measurements. We used as-grown SiNWs tapered along the growth direction with progressively lower roughness and SFs density. The results clearly confirmed that both surface roughness and twins or SFs densities suppress the thermal conductivity of an individual SiNW. The results and measurement techniques presented here hold great potential for inspecting minute changes in thermal resistance along an individual SiNW, caused by induced SFs on the nanostructure, and for improving one-dimensional nanowire-based thermoelectric device performance.

Solid-state Distributed Temperature Control for International Space Station

NASA Technical Reports Server (NTRS)

Holladay, Jon B.; Reagan, Shawn E.; Day, Greg

2004-01-01

A newly developed solid-state temperature controller will offer greater flexibility in the thermal control of aerospace vehicle structures. A status of the hardware development along with its implementation on the Multi- Purpose Logistics Module will be provided. Numerous advantages of the device will also be discussed with regards to current and future flight vehicle implementations.

Thermal electron-tunneling devices as coolers and amplifiers

NASA Astrophysics Data System (ADS)

Su, Shanhe; Zhang, Yanchao; Chen, Jincan; Shih, Tien-Mo

2016-02-01

Nanoscale thermal systems that are associated with a pair of electron reservoirs have been previously studied. In particular, devices that adjust electron tunnels relatively to reservoirs’ chemical potentials enjoy the novelty and the potential. Since only two reservoirs and one tunnel exist, however, designers need external aids to complete a cycle, rendering their models non-spontaneous. Here we design thermal conversion devices that are operated among three electron reservoirs connected by energy-filtering tunnels and also referred to as thermal electron-tunneling devices. They are driven by one of electron reservoirs rather than the external power input, and are equivalent to those coupling systems consisting of forward and reverse Carnot cycles with energy selective electron functions. These previously-unreported electronic devices can be used as coolers and thermal amplifiers and may be called as thermal transistors. The electron and energy fluxes of devices are capable of being manipulated in the same or oppsite directions at our disposal. The proposed model can open a new field in the application of nano-devices.

Thermal electron-tunneling devices as coolers and amplifiers

PubMed Central

Su, Shanhe; Zhang, Yanchao; Chen, Jincan; Shih, Tien-Mo

2016-01-01

Nanoscale thermal systems that are associated with a pair of electron reservoirs have been previously studied. In particular, devices that adjust electron tunnels relatively to reservoirs’ chemical potentials enjoy the novelty and the potential. Since only two reservoirs and one tunnel exist, however, designers need external aids to complete a cycle, rendering their models non-spontaneous. Here we design thermal conversion devices that are operated among three electron reservoirs connected by energy-filtering tunnels and also referred to as thermal electron-tunneling devices. They are driven by one of electron reservoirs rather than the external power input, and are equivalent to those coupling systems consisting of forward and reverse Carnot cycles with energy selective electron functions. These previously-unreported electronic devices can be used as coolers and thermal amplifiers and may be called as thermal transistors. The electron and energy fluxes of devices are capable of being manipulated in the same or oppsite directions at our disposal. The proposed model can open a new field in the application of nano-devices. PMID:26893109

Realization of a thermal cloak-concentrator using a metamaterial transformer.

PubMed

Liu, Ding-Peng; Chen, Po-Jung; Huang, Hsin-Haou

2018-02-06

By combining rotating squares with auxetic properties, we developed a metamaterial transformer capable of realizing metamaterials with tunable functionalities. We investigated the use of a metamaterial transformer-based thermal cloak-concentrator that can change from a cloak to a concentrator when the device configuration is transformed. We established that the proposed dual-functional metamaterial can either thermally protect a region (cloak) or focus heat flux in a small region (concentrator). The dual functionality was verified by finite element simulations and validated by experiments with a specimen composed of copper, epoxy, and rotating squares. This work provides an effective and efficient method for controlling the gradient of heat, in addition to providing a reference for other thermal metamaterials to possess such controllable functionalities by adapting the concept of a metamaterial transformer.

Analytical investigations on the thermal properties of microscale inorganic light-emitting diodes on an orthotropic substrate

NASA Astrophysics Data System (ADS)

Li, Y.; Chen, J.; Xing, Y.; Song, J.

2017-03-01

The microscale inorganic light-emitting diodes (μ-ILEDs) create novel opportunities in biointegrated applications such as wound healing acceleration and optogenetics. Analytical expressions, validated by finite element analysis, are obtained for the temperature increase of a rectangular μ-ILED device on an orthotropic substrate, which could offer an appealing advantage in controlling the heat flow direction to achieve the goal in thermal management. The influences of various parameters (e.g., thermal conductivities of orthotropic substrate, loading parameters) on the temperature increase of the μ-ILED are investigated based on the obtained closed-form solutions. These results provide a novel route to control the temperature distribution in the μ-ILED system and provide easily interpretable guidelines to minimize the adverse thermal effects.

Open cycle gas core nuclear rockets

NASA Technical Reports Server (NTRS)

Ragsdale, Robert

1991-01-01

The open cycle gas core engine is a nuclear propulsion device. Propulsion is provided by hot hydrogen which is heated directly by thermal radiation from the nuclear fuel. Critical mass is sustained in the uranium plasma in the center. It has typically 30 to 50 kg of fuel. It is a thermal reactor in the sense that fissions are caused by absorption of thermal neutrons. The fast neutrons go out to an external moderator/reflector material and, by collision, slow down to thermal energy levels, and then come back in and cause fission. The hydrogen propellant is stored in a tank. The advantage of the concept is very high specific impulse because you can take the plasma to any temperature desired by increasing the fission level by withdrawing or turning control rods or control drums.

Fabrication and Performance of Large Format Transition Edge Sensor Microcalorimeter Arrays

NASA Technical Reports Server (NTRS)

Chervenak, James A.; Adams, James S.; Bandler, Simon R.; Busch, Sara E.; Eckart, M. E.; Ewin, A. E.; Finkbeiner, F. M.; Kilbourne, C. A.; Kelley, R. L.; Porst, Jan-Patrick;

40 CFR 265.383 - Interim status thermal treatment devices burning particular hazardous waste.

Code of Federal Regulations, 2010 CFR

2010-07-01

... devices burning particular hazardous waste. 265.383 Section 265.383 Protection of Environment... status thermal treatment devices burning particular hazardous waste. (a) Owners or operators of thermal treatment devices subject to this subpart may burn EPA Hazardous Wastes FO20, FO21, FO22, FO23, FO26, or...

40 CFR 265.383 - Interim status thermal treatment devices burning particular hazardous waste.

Code of Federal Regulations, 2013 CFR

2013-07-01

... devices burning particular hazardous waste. 265.383 Section 265.383 Protection of Environment... status thermal treatment devices burning particular hazardous waste. (a) Owners or operators of thermal treatment devices subject to this subpart may burn EPA Hazardous Wastes FO20, FO21, FO22, FO23, FO26, or...

40 CFR 265.383 - Interim status thermal treatment devices burning particular hazardous waste.

Code of Federal Regulations, 2014 CFR

2014-07-01

... devices burning particular hazardous waste. 265.383 Section 265.383 Protection of Environment... status thermal treatment devices burning particular hazardous waste. (a) Owners or operators of thermal treatment devices subject to this subpart may burn EPA Hazardous Wastes FO20, FO21, FO22, FO23, FO26, or...

40 CFR 265.383 - Interim status thermal treatment devices burning particular hazardous waste.

Code of Federal Regulations, 2012 CFR

2012-07-01

... devices burning particular hazardous waste. 265.383 Section 265.383 Protection of Environment... status thermal treatment devices burning particular hazardous waste. (a) Owners or operators of thermal treatment devices subject to this subpart may burn EPA Hazardous Wastes FO20, FO21, FO22, FO23, FO26, or...

40 CFR 265.383 - Interim status thermal treatment devices burning particular hazardous waste.

Code of Federal Regulations, 2011 CFR

2011-07-01

... devices burning particular hazardous waste. 265.383 Section 265.383 Protection of Environment... status thermal treatment devices burning particular hazardous waste. (a) Owners or operators of thermal treatment devices subject to this subpart may burn EPA Hazardous Wastes FO20, FO21, FO22, FO23, FO26, or...

An experimental and theoretical evaluation of increased thermal diffusivity phase change devices

NASA Technical Reports Server (NTRS)

White, S. P.; Golden, J. O.; Stermole, F. J.

1972-01-01

This study was to experimentally evaluate and mathematically model the performance of phase change thermal control devices containing high thermal conductivity metal matrices. Three aluminum honeycomb filters were evaluated at five different heat flux levels using n-oct-adecane as the test material. The system was mathematically modeled by approximating the partial differential equations with a three-dimensional implicit alternating direction technique. The mathematical model predicts the system quite well. All of the phase change times are predicted. The heating of solid phase is predicted exactly while there is some variation between theoretical and experimental results in the liquid phase. This variation in the liquid phase could be accounted for by the fact that there are some heat losses in the cell and there could be some convection in the experimental system.

The thermal stability of sodium beta'-Alumina solid electrolyte ceramic in AMTEC cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Williams, Roger M.; Ryan, Margaret A.; Homer, Margie L.

1999-01-22

A critical component of alkali metal thermal-to electric converter (AMTEC) devices for long duration space missions is the beta'-alumina solid electrolyte ceramic (BASE), for which there exists no substitute. The temperature and environmental conditions under which BASE remains stable control operational parameters of AMTEC devices. We have used mass loss experiments in vacuum to 1573K to characterize the kinetics of BASE decomposition, and conductivity and exchange current measurements in sodium vapor filled exposure cells to 1223K to investigate changes in the BASE which affect its ionic conductivity. There is no clear evidence of direct thermal decomposition of BASE below 1273K,more » although limited soda loss may occur. Reactive metals such as Mn or Cr can react with BASE at temperatures at least as low as 1223K.« less

Applications of high thermal conductivity composites to electronics and spacecraft thermal design

NASA Technical Reports Server (NTRS)

Sharp, G. Richard; Loftin, Timothy A.

1990-01-01

Recently, high thermal conductivity continuous graphite fiber reinforced metal matrix composites (MMC's) have become available that can save much weight over present methods of heat conduction. These materials have two or three times higher thermal conductivity in the fiber direction than the pure metals when compared on a thermal conductivity to weight basis. Use of these materials for heat conduction purposes can result in weight savings of from 50 to 70 percent over structural aluminum. Another significant advantage is that these materials can be used without the plumbing and testing complexities that accompany the use of liquid heat pipes. A spinoff of this research was the development of other MMC's as electronic device heat sinks. These use particulates rather than fibers and are formulated to match the coefficient of thermal expansion of electronic substrates in order to alleviate thermally induced stresses. The development of both types of these materials as viable weight saving substitutes for traditional methods of thermal control for electronics packaging and also for spacecraft thermal control applications are the subject of this report.

Endocervical ultrasound applicator for integrated hyperthermia and HDR brachytherapy in the treatment of locally advanced cervical carcinoma.

PubMed

Wootton, Jeffery H; Hsu, I-Chow Joe; Diederich, Chris J

2011-02-01

The clinical success of hyperthermia adjunct to radiotherapy depends on adequate temperature elevation in the tumor with minimal temperature rise in organs at risk. Existing technologies for thermal treatment of the cervix have limited spatial control or rapid energy falloff. The objective of this work is to develop an endocervical applicator using a linear array of multisectored tubular ultrasound transducers to provide 3-D conformal, locally targeted hyperthermia concomitant to radiotherapy in the uterine cervix. The catheter-based device is integrated within a HDR brachytherapy applicator to facilitate sequential and potentially simultaneous heat and radiation delivery. Treatment planning images from 35 patients who underwent HDR brachytherapy for locally advanced cervical cancer were inspected to assess the dimensions of radiation clinical target volumes (CTVs) and gross tumor volumes (GTVs) surrounding the cervix and the proximity of organs at risk. Biothermal simulation was used to identify applicator and catheter material parameters to adequately heat the cervix with minimal thermal dose accumulation in nontargeted structures. A family of ultrasound applicators was fabricated with two to three tubular transducers operating at 6.6-7.4 MHz that are unsectored (360 degrees), bisectored (2 x 180 degrees), or trisectored (3 x 120 degrees) for control of energy deposition in angle and along the device length in order to satisfy anatomical constraints. The device is housed in a 6 mm diameter PET catheter with cooling water flow for endocervical implantation. Devices were characterized by measuring acoustic efficiencies, rotational acoustic intensity distributions, and rotational temperature distributions in phantom. The CTV in HDR brachytherapy plans extends 20.5 +/- 5.0 mm from the endocervical tandem with the rectum and bladder typically <8 mm from the target boundary. The GTV extends 19.4 +/- 7.3 mm from the tandem. Simulations indicate that for 60 min treatments the applicator can heat to 41 degrees C and deliver > 5EM(43 degrees C) over 4-5 cm diameter with Tmax < 45 degrees C and 1 kg m(-3) s(-1) blood perfusion. The 41 degrees C contour diameter is reduced to 3-4 cm at 3 kg m(-3) s(-1) perfusion. Differential power control to transducer elements and sectors demonstrates tailoring of heating along the device length and in angle. Sector cuts are associated with a 14-47 degrees acoustic dead zone, depending on cut width, resulting in a approximately 2-4 degrees C temperature reduction within the dead zone below Tmax. Dead zones can be oriented for thermal protection of the rectum and bladder. Fabricated devices have acoustic efficiencies of 33.4%-51.8% with acoustic output that is well collimated in length, reflects the sectoring strategy, and is strongly correlated with temperature distributions. A catheter-based ultrasound applicator was developed for endocervical implantation with locally targeted, 3-D conformal thermal delivery to the uterine cervix. Feasibility of heating clinically relevant target volumes was demonstrated with power control along the device length and in angle to treat the cervix with minimal thermal dose delivery to the rectum and bladder.

A programmable heater control circuit for spacecraft

NASA Technical Reports Server (NTRS)

Nguyen, D. D.; Owen, J. W.; Smith, D. A.; Lewter, W. J.

1994-01-01

Spacecraft thermal control is accomplished for many components through use of multilayer insulation systems, electrical heaters, and radiator systems. The heaters are commanded to maintain component temperatures within design specifications. The programmable heater control circuit (PHCC) was designed to obtain an effective and efficient means of spacecraft thermal control. The hybrid circuit provides use of control instrumentation as temperature data, available to the spacecraft central data system, reprogramming capability of the local microprocessor during the spacecraft's mission, and the elimination of significant spacecraft wiring. The hybrid integrated circuit has a temperature sensing and conditioning circuit, a microprocessor, and a heater power and control circuit. The device is miniature and housed in a volume which allows physical integration with the component to be controlled. Applications might include alternate battery-powered logic-circuit configurations. A prototype unit with appropriate physical and functional interfaces was procured for testing. The physical functionality and the feasibility of fabrication of the hybrid integrated circuit were successfully verified. The remaining work to develop a flight-qualified device includes fabrication and testing of a Mil-certified part. An option for completing the PHCC flight qualification testing is to enter into a joint venture with industry.

CONTROL DEVICE

DOEpatents

Dickson, J.J.

1959-09-15

A bimetallic helix is described comprising a neutronflux-responsive strip and a second strip having the same coefficient of thermal expansion for adjusting the extent to which an inner neutron-absorbing member protrudes from an outer hollow neutron-absorbing member.

Designing a Polymerase Chain Reaction Device Working with Radiation and Convection Heat Transfer

NASA Astrophysics Data System (ADS)

Madadelahi, M.; Kalan, K.; Shamloo, A.

2018-05-01

Gene proliferation is vital for infectious and genetic diseases diagnosis from a blood sample, even before birth. In addition, DNA sequencing, genetic finger-print analyzing, and genetic mutation detecting can be mentioned as other procedures requiring gene reproduction. Polymerase chain reaction, briefly known as PCR, is a convenient and effective way to accomplish this task; where the DNA containing sample faces three temperature phases alternatively. These phases are known as denaturation, annealing, and elongation/extension which in this study -regarding the type of the primers and the target DNA sequence- are set to occur at 95, 58, and 72 degrees of Celsius. In this study, a PCR device has been designed and fabricated which uses radiation and convection heat transfer at the same time to set and control the mentioned thermal sections. A 300W incandescent light bulb able to immediately turn off and on along with two 8×8 cm DC fans, controlled by a microcontroller as well as PID and PD controller codes are used to monitor the applied thermal cycles. In designing the controller codes it has been concerned that they not only control the temperature over the set-points as well as possible, but also increase the temperature variation rate between each two phases. The temperature data were plotted and DNA samples were used to assess the device function.

Quantum Thermal Transistor.

PubMed

Joulain, Karl; Drevillon, Jérémie; Ezzahri, Younès; Ordonez-Miranda, Jose

2016-05-20

We demonstrate that a thermal transistor can be made up with a quantum system of three interacting subsystems, coupled to a thermal reservoir each. This thermal transistor is analogous to an electronic bipolar one with the ability to control the thermal currents at the collector and at the emitter with the imposed thermal current at the base. This is achieved by determining the heat fluxes by means of the strong-coupling formalism. For the case of three interacting spins, in which one of them is coupled to the other two, that are not directly coupled, it is shown that high amplification can be obtained in a wide range of energy parameters and temperatures. The proposed quantum transistor could, in principle, be used to develop devices such as a thermal modulator and a thermal amplifier in nanosystems.

Patterning and reduction of graphene oxide using femtosecond-laser irradiation

NASA Astrophysics Data System (ADS)

Kang, SeungYeon; Evans, Christopher C.; Shukla, Shobha; Reshef, Orad; Mazur, Eric

2018-07-01

Graphene has emerged as one of the most versatile materials ever discovered due to its extraordinary electronic, optical, thermal, and mechanical properties. However, device fabrication is a well-known challenge and requires novel fabrication methods to realize the complex integration of graphene-based devices. Here, we demonstrate direct laser writing of reduced graphene oxide using femtosecond-laser irradiation at λ = 795 nm. We perform a systematic study of the reduction process of graphene oxide to graphene by varying both the laser fluence and the pulse repetition rate. Our observations show that the reduction has both thermal and non-thermal features, and suggest that we can achieve better resolution and conductivity using kHz pulse trains than using MHz pulse trains or a continuous wave laser. Our reduced graphene oxide lines written at 10-kHz exhibit a 5 order-of-magnitude decrease in resistivity compared to a non-irradiated control sample. This study provides new insight into the reduction process of graphene oxide and opens doors to achieving a high degree of flexibility and control in the fabrication of graphene layers.

Magnon-drag thermopile.

PubMed

Costache, Marius V; Bridoux, German; Neumann, Ingmar; Valenzuela, Sergio O

2011-12-18

Thermoelectric effects in spintronics are gathering increasing attention as a means of managing heat in nanoscale structures and of controlling spin information by using heat flow. Thermal magnons (spin-wave quanta) are expected to play a major role; however, little is known about the underlying physical mechanisms involved. The reason is the lack of information about magnon interactions and of reliable methods to obtain it, in particular for electrical conductors because of the intricate influence of electrons. Here, we demonstrate a conceptually new device that enables us to gather information on magnon-electron scattering and magnon-drag effects. The device resembles a thermopile formed by a large number of pairs of ferromagnetic wires placed between a hot and a cold source and connected thermally in parallel and electrically in series. By controlling the relative orientation of the magnetization in pairs of wires, the magnon drag can be studied independently of the electron and phonon-drag thermoelectric effects. Measurements as a function of temperature reveal the effect on magnon drag following a variation of magnon and phonon populations. This information is crucial to understand the physics of electron-magnon interactions, magnon dynamics and thermal spin transport.

Novel Micro ElectroMechanical Systems (MEMS) Packaging for the Skin of the Satellite

NASA Technical Reports Server (NTRS)

Darrin, M. Ann; Osiander, Robert; Lehtonen, John; Farrar, Dawnielle; Douglas, Donya; Swanson, Ted

2004-01-01

This paper includes a discussion of the novel packaging techniques that are needed to place MEMS based thermal control devices on the skin of various satellites, eliminating the concern associated with potential particulates &om integration and test or the launch environment. Protection of this MEMS based thermal device is achieved using a novel polymer that is both IR transmissive and electrically conductive. This polymer was originally developed and qualified for space flight application by NASA at the Langley Research Center. The polymer material, commercially known as CPI, is coated with a thin layer of ITO and sandwiched between two window-like frames. The packaging of the MEMS based radiator assembly offers the benefits of micro-scale devices in a chip on board fashion, with the level of protection generally found in packaged parts.

Sub-100 fJ and sub-nanosecond thermally driven threshold switching in niobium oxide crosspoint nanodevices.

PubMed

Pickett, Matthew D; Williams, R Stanley

2012-06-01

We built and measured the dynamical current versus time behavior of nanoscale niobium oxide crosspoint devices which exhibited threshold switching (current-controlled negative differential resistance). The switching speeds of 110 × 110 nm(2) devices were found to be Δt(ON) = 700 ps and Δt(OFF) = 2:3 ns while the switching energies were of the order of 100 fJ. We derived a new dynamical model based on the Joule heating rate of a thermally driven insulator-to-metal phase transition that accurately reproduced the experimental results, and employed the model to estimate the switching time and energy scaling behavior of such devices down to the 10 nm scale. These results indicate that threshold switches could be of practical interest in hybrid CMOS nanoelectronic circuits.

Capillary Two-Phase Thermal Devices for Space Applications

NASA Technical Reports Server (NTRS)

Ku, Jentung

2016-01-01

This is the presentation file for an invited seminar for Department of Mechanical and Aerospace Engineering at the Case Western Reserve University. The seminar is scheduled for April 1, 2016.Description: This presentation will discuss operating principles and performance characteristics of heat pipes (HPs) and loop heat pipes (LHPs) and their application for spacecraft thermal control. Topics include: 1) HP operating principles; 2) HP performance characteristics; 3) LHP pressure profiles; 4) LHP operating temperature; 5) LHP operating temperature control; and 6) Examples of using HPs and LHPs on NASA flight projects.

Device for thermal transfer and power generation

DOEpatents

Weaver, Stanton Earl [Northville, NY; Arik, Mehmet [Niskayuna, NY

2011-04-19

A system is provided. The system includes a device that includes top and bottom thermally conductive substrates positioned opposite to one another, wherein a top surface of the bottom thermally conductive substrate is substantially atomically flat and a thermal blocking layer disposed between the top and bottom thermally conductive substrates. The device also includes top and bottom electrodes separated from one another between the top and bottom thermally conductive substrates to define a tunneling path, wherein the top electrode is disposed on the thermal blocking layer and the bottom electrode is disposed on the bottom thermally conductive substrate.

A nanophotonic solar thermophotovoltaic device.

PubMed

Lenert, Andrej; Bierman, David M; Nam, Youngsuk; Chan, Walker R; Celanović, Ivan; Soljačić, Marin; Wang, Evelyn N

2014-02-01

The most common approaches to generating power from sunlight are either photovoltaic, in which sunlight directly excites electron-hole pairs in a semiconductor, or solar-thermal, in which sunlight drives a mechanical heat engine. Photovoltaic power generation is intermittent and typically only exploits a portion of the solar spectrum efficiently, whereas the intrinsic irreversibilities of small heat engines make the solar-thermal approach best suited for utility-scale power plants. There is, therefore, an increasing need for hybrid technologies for solar power generation. By converting sunlight into thermal emission tuned to energies directly above the photovoltaic bandgap using a hot absorber-emitter, solar thermophotovoltaics promise to leverage the benefits of both approaches: high efficiency, by harnessing the entire solar spectrum; scalability and compactness, because of their solid-state nature; and dispatchablility, owing to the ability to store energy using thermal or chemical means. However, efficient collection of sunlight in the absorber and spectral control in the emitter are particularly challenging at high operating temperatures. This drawback has limited previous experimental demonstrations of this approach to conversion efficiencies around or below 1% (refs 9, 10, 11). Here, we report on a full solar thermophotovoltaic device, which, thanks to the nanophotonic properties of the absorber-emitter surface, reaches experimental efficiencies of 3.2%. The device integrates a multiwalled carbon nanotube absorber and a one-dimensional Si/SiO2 photonic-crystal emitter on the same substrate, with the absorber-emitter areas optimized to tune the energy balance of the device. Our device is planar and compact and could become a viable option for high-performance solar thermophotovoltaic energy conversion.

Materials for electrochemical device safety

DOEpatents

Vissers, Daniel R.; Amine, Khalil; Thackeray, Michael M.; Kahaian, Arthur J.; Johnson, Christopher S.

2015-04-07

An electrochemical device includes a thermally-triggered intumescent material or a gas-triggered intumescent material. Such devices prevent or minimize short circuits in a device that could lead to thermal run-away. Such devices may include batteries or supercapacitors.

Energy Dissipation and Transport in Carbon Nanotube Devices

NASA Astrophysics Data System (ADS)

Pop, Eric

2011-03-01

Power consumption is a significant challenge in electronics, often limiting the performance of integrated circuits from mobile devices to massive data centers. Carbon nanotubes have emerged as potentially energy-efficient future devices and interconnects, with both large mobility and thermal conductivity. This talk will focus on understanding and controlling energy dissipation [1-3] and transport [4-6] in carbon nanotubes, with applications to low-energy devices, interconnects, heat sinks, and memory elements. Experiments have been used to gain new insight into the fundamental behavior of such devices, and to better inform practical device models. The results suggest much room for energy optimization in nanoelectronics through the design of geometry, interfaces, and materials..

0-π phase-controllable thermal Josephson junction

NASA Astrophysics Data System (ADS)

Fornieri, Antonio; Timossi, Giuliano; Virtanen, Pauli; Solinas, Paolo; Giazotto, Francesco

2017-05-01

Two superconductors coupled by a weak link support an equilibrium Josephson electrical current that depends on the phase difference ϕ between the superconducting condensates. Yet, when a temperature gradient is imposed across the junction, the Josephson effect manifests itself through a coherent component of the heat current that flows opposite to the thermal gradient for |ϕ| < π/2 (refs 2-4). The direction of both the Josephson charge and heat currents can be inverted by adding a π shift to ϕ. In the static electrical case, this effect has been obtained in a few systems, for example via a ferromagnetic coupling or a non-equilibrium distribution in the weak link. These structures opened new possibilities for superconducting quantum logic and ultralow-power superconducting computers. Here, we report the first experimental realization of a thermal Josephson junction whose phase bias can be controlled from 0 to π. This is obtained thanks to a superconducting quantum interferometer that allows full control of the direction of the coherent energy transfer through the junction. This possibility, in conjunction with the completely superconducting nature of our system, provides temperature modulations with an unprecedented amplitude of ∼100 mK and transfer coefficients exceeding 1 K per flux quantum at 25 mK. Then, this quantum structure represents a fundamental step towards the realization of caloritronic logic components such as thermal transistors, switches and memory devices. These elements, combined with heat interferometers and diodes, would complete the thermal conversion of the most important phase-coherent electronic devices and benefit cryogenic microcircuits requiring energy management, such as quantum computing architectures and radiation sensors.

Die Attachment for -120 C to +20 C Thermal Cycling of Microelectronics for Future Mars Rovers: An Overview

NASA Technical Reports Server (NTRS)

Kirschman, Randall K.; Sokolowski, Witold M.; Kolawa, Elizabeth A.

1999-01-01

Active thermal control for electronics on Mars Rovers imposes a serious penalty in weight, volume, power consumption, and reliability. Thus, we propose that thermal control be eliminated for future Rovers. From a functional standpoint there is no reason that the electronics could not operate over the entire temperature range of the Martian environment, which can vary from a low of approximately equal -90 C to a high of approximately equal +20 C during the Martian night and day. The upper end of this range is well within that for conventional electronics. Although the lower end is considerably below that for which conventional--even high-reliability electronics is designed or tested, it is well established that electronic devices can operate to such low temperatures. The primary concern is reliability of the overall electronic system, especially in regard to the numerous daily temperature cycles that it would experience over the duration of a mission on Mars. Accordingly, key reliability issues have been identified for elimination of thermal control on future Mars Rovers. One of these is attachment of semiconductor die onto substrates and into packages. Die attachment is critical since it forms a mechanical, thermal and electrical interface between the electronic device and the substrate or package. This paper summarizes our initial investigation of existing information related to this issue, in order to form an opinion whether die attachment techniques exist, or could be developed with reasonable effort, to withstand the Mars thermal environment for a mission duration of approximately I year. Our conclusion, from a review of literature and personal contacts. is that die attachment can be made sufficiently reliable to satisfy the requirements of future Mars Rovers. Moreover, it appears that there are several possible techniques from which to choose and that the requirements could be met by judicious selection from existing methods using hard solders, soft solders, or organic adhesives. Thus from the standpoint of die attachment. it appears feasible to eliminate thermal control for Rover electronics. We recommend that this be further investigated and verified for the specific hardware and thermal conditions appropriate to Mars Rovers.

Design and development of integral heat pipe/thermal energy storage devices. [used with spacecraft cryocoolers

NASA Technical Reports Server (NTRS)

Mahefkey, E. T.; Richter, R.

1981-01-01

The major design and performance test subtasks in the development of small (200 to 1,000 whr) integral heat pipe/thermal energy storage devices for use with thermally driven spacecraft cryo-coolers are described. The design of the integral heat pipe/thermal energy storage device was based on a quasi steady resistance heat transfer, lumped capacitance model. Design considerations for the heat pipe and thermal storage annuli are presented. The thermomechanical stress and insulation system design for the device are reviewed. Experimental correlations are described, as are the plans for the further development of the concept.

Design and development of integral heat pipe/thermal energy storage devices

NASA Astrophysics Data System (ADS)

Mahefkey, E. T.; Richter, R.

1981-06-01

The major design and performance test subtasks in the development of small (200 to 1,000 whr) integral heat pipe/thermal energy storage devices for use with thermally driven spacecraft cryo-coolers are described. The design of the integral heat pipe/thermal energy storage device was based on a quasi steady resistance heat transfer, lumped capacitance model. Design considerations for the heat pipe and thermal storage annuli are presented. The thermomechanical stress and insulation system design for the device are reviewed. Experimental correlations are described, as are the plans for the further development of the concept.

An Automatic Occlusion Device for Remote Control of Tumor Tissue Ischemia

PubMed Central

El-Dahdah, Hamid; Wang, Bei; He, Guanglong; Xu, Ronald X.

2015-01-01

We developed an automatic occlusion device for remote control of tumor tissue ischemia. The device consists of a flexible cannula encasing a shape memory alloy wire with its distal end connected to surgical suture. Regional tissue occlusion was tested on both the benchtop and the animal models. In the benchtop test, the occlusion device introduced quantitative and reproducible changes of blood flow in a tissue simulating phantom embedding a vessel simulator. In the animal test, the device generated a cyclic pattern of reversible ischemia in the right hinder leg tissue of a black male C57BL/6 mouse. We also developed a multimodal detector that integrates near infrared spectroscopy and electron paramagnetic resonance spectroscopy for continuous monitoring of tumor tissue oxygenation, blood content, and oxygen tension changes. The multimodal detector was tested on a cancer xenograft nude mouse undergoing reversible tumor ischemia. The automatic occlusion device and the multi-modal detector can be potentially integrated for closed-loop feedback control of tumor tissue ischemia. Such an integrated occlusion device may be used in multiple clinical applications such as regional hypoperfusion control in tumor resection surgeries and thermal ablation processes. In addition, the proposed occlusion device can also be used as a research tool to understand tumor oxygen transport and hemodynamic characteristics. PMID:20082532

Thermal Management Considerations in Energy Conversion Devices

DTIC Science & Technology

2001-05-01

1000 W). Thermal Conversion Devices: Thermoelectrics (TE) Thermophotovoltaics (TPV) Alkali Metal Thermal to Electric Conversion (AMTEC) Free...300 - 400C Heat Input 700 - 850C Na vapor Electrodes Alkali Metal Thermal - to - Electric Conversion: Sodium is vaporized and condensed in a thermally

A Real-Time Thermal Self-Elimination Method for Static Mode Operated Freestanding Piezoresistive Microcantilever-Based Biosensors

PubMed Central

Ku, Yu-Fu; Huang, Long-Sun

2018-01-01

Here, we provide a method and apparatus for real-time compensation of the thermal effect of single free-standing piezoresistive microcantilever-based biosensors. The sensor chip contained an on-chip fixed piezoresistor that served as a temperature sensor, and a multilayer microcantilever with an embedded piezoresistor served as a biomolecular sensor. This method employed the calibrated relationship between the resistance and the temperature of piezoresistors to eliminate the thermal effect on the sensor, including the temperature coefficient of resistance (TCR) and bimorph effect. From experimental results, the method was verified to reduce the signal of thermal effect from 25.6 μV/°C to 0.3 μV/°C, which was approximately two orders of magnitude less than that before the processing of the thermal elimination method. Furthermore, the proposed approach and system successfully demonstrated its effective real-time thermal self-elimination on biomolecular detection without any thermostat device to control the environmental temperature. This method realizes the miniaturization of an overall measurement system of the sensor, which can be used to develop portable medical devices and microarray analysis platforms. PMID:29495574

TES development for a frequency selective bolometer camera.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Datesman, A. M.; Downes, T. P.; Perera, T. A.

2009-06-01

We discuss the development, at Argonne National Laboratory (ANL), of a four-pixel camera with four spectral channels centered at 150, 220, 270, and 360 GHz. The scientific motivation involves photometry of distant dusty galaxies located by Spitzer and SCUBA, as well as the study of other millimeter-wave sources such as ultra-luminous infrared galaxies, the Sunyaev-Zeldovich effect in clusters, and galactic dust. The camera incorporates Frequency Selective Bolometer (FSB) and superconducting Transition-Edge Sensor (TES) technology. The current generation of TES devices we examine utilizes proximity effect superconducting bilayers of Mo/Au, Ti, or Ti/Au as TESs, located along with frequency selective absorbingmore » structures on silicon nitride membranes. The detector incorporates lithographically patterned structures designed to address both TES device stability and detector thermal transport concerns. The membrane is not perforated, resulting in a detector which is comparatively robust mechanically. In this paper, we report on the development of the superconducting bilayer TES technology, the design and testing of the detector thermal transport and device stability control structures, optical and thermal test results, and the use of new materials.« less

A thermal-sensitive device fabricated with diamond film and a planar microelectrode

DOE Office of Scientific and Technical Information (OSTI.GOV)

Changzhi Gu; Zengsun Jin; Xianyi Lu

1995-12-31

Polycrystalline diamond film were deposited by means of the hot filament CVD technique (HFCVD) onto a planar interdigital Ti microelectrode arrays, and forming a thermal-sensitive device, The resistor changes of diamond film caused by temperature are shown to be sensitive, reproducible, rapid and stable thermal-sensitive device. The characteristics of thermal-sensitive for this device was study. Functionalized diamond film deposited onto planar microelectrode arrays can easily detect temperature from 20{degrees}C to 700{degrees}C.

Photoresponse of an electrically tunable ambipolar graphene infrared thermocouple.

PubMed

Herring, Patrick K; Hsu, Allen L; Gabor, Nathaniel M; Shin, Yong Cheol; Kong, Jing; Palacios, Tomás; Jarillo-Herrero, Pablo

2014-02-12

We explore the photoresponse of an ambipolar graphene infrared thermocouple at photon energies close to or below monolayer graphene's optical phonon energy and electrostatically accessible Fermi energy levels. The ambipolar graphene infrared thermocouple consists of monolayer graphene supported by an infrared absorbing material, controlled by two independent electrostatic gates embedded below the absorber. Using a scanning infrared laser microscope, we characterize these devices as a function of carrier type and carrier density difference controlled at the junction between the two electrostatic gates. On the basis of these measurements, conducted at both mid- and near-infrared wavelengths, the primary detection mechanism can be modeled as a thermoelectric response. By studying the effect of different infrared absorbers, we determine that the optical absorption and thermal conduction of the substrate play the dominant role in the measured photoresponse of our devices. These experiments indicate a path toward hybrid graphene thermal detectors for sensing applications such as thermography and chemical spectroscopy.

Malgorzata Kasperska Henryk Bunka

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

The MarCo Engineering Company Ltd. has its registered seat at Gdynia and was established in 1990. We are the exclusive representative for Poland of the world`s renowned manufacturers of heat distribution network products; Through six subsidiaries (Gdynia, Warsaw, Wroclaw, Cracow, Gliwice and Lublin) and our dealers` network all over Poland the following products and services are offered: (1) automatic control systems for heating and air conditioning; (2) a supervisory remote control system for heat distribution centers; (3) compensating devices for central heating and household hot water installations; (4) radiator thermostatic valves; (5) Meinecke water meters; (6) thermal energy counters; (6)more » a remote calorimeter data reading system SIOX; (7) an electronic central heating costs sharing system - GT-15; (8) compact thermal stations; and (9) compact and pipe exchangers. The modern, high standard devices offered have achieved much success on the Polish market.« less

Memristor and selector devices fabricated from HfO2-xNx

NASA Astrophysics Data System (ADS)

Murdoch, B. J.; McCulloch, D. G.; Ganesan, R.; McKenzie, D. R.; Bilek, M. M. M.; Partridge, J. G.

2016-04-01

Monoclinic HfO2-xNx has been incorporated into two-terminal devices exhibiting either memristor or selector operation depending on the controlled inclusion/suppression of mobile oxygen vacancies. In HfO2 memristors containing oxygen vacancies, gradual conductance modulation, short-term plasticity, and long-term potentiation were observed using appropriate voltage-spike stimulation, suggesting suitability for artificial neural networks. Passivation of oxygen vacancies, confirmed by X-ray absorption spectroscopy, was achieved in HfO2-xNx films by the addition of nitrogen during growth. Selector devices formed on these films exhibited threshold switching and current controlled negative differential resistance consistent with thermally driven insulator to metal transitions.

Buffer thermal energy storage for an air Brayton solar engine

NASA Technical Reports Server (NTRS)

Strumpf, H. J.; Barr, K. P.

1981-01-01

The application of latent-heat buffer thermal energy storage to a point-focusing solar receiver equipped with an air Brayton engine was studied. To demonstrate the effect of buffer thermal energy storage on engine operation, a computer program was written which models the recuperator, receiver, and thermal storage device as finite-element thermal masses. Actual operating or predicted performance data are used for all components, including the rotating equipment. Based on insolation input and a specified control scheme, the program predicts the Brayton engine operation, including flows, temperatures, and pressures for the various components, along with the engine output power. An economic parametric study indicates that the economic viability of buffer thermal energy storage is largely a function of the achievable engine life.

Conjunction of standing wave and resonance in asymmetric nanowires: a mechanism for thermal rectification and remote energy accumulation.

PubMed

Liu, Yue-Yang; Zhou, Wu-Xing; Chen, Ke-Qiu

2015-12-02

As an important way to control and manage heat transport, thermal rectification has become an elementary issue in the field of phononics and plays a key role in the designing of thermal devices. Here we investigate systematically the standing wave and the accompanying resonance process in asymmetric nanowires to understand the standing wave itself and its great effect on thermal rectification. Results show that the standing wave is sensitive to both the structural and thermal properties of the material, and its great effect on enhancing the thermal rectification is realized not only by the energy-localization nature of the standing wave, but also by the resonance-caused large amplitude and high energy of the standing wave.

Testing of a Methane Cryogenic Heat Pipe with a Liquid Trap Turn-Off Feature for use on Space Interferometer Mission (SIM)

NASA Technical Reports Server (NTRS)

Cepeda-Rizo, Juan; Krylo, Robert; Fisher, Melanie; Bugby, David C.

2011-01-01

Camera cooling for SIM presents three thermal control challenges; stable operation at 163K (110 C), decontamination heating to +20 C, and a long span from the cameras to the radiator. A novel cryogenic cooling system based on a methane heat pipe meets these challenges. The SIM thermal team, with the help of heat pipe vendor ATK, designed and tested a complete, low temperature, cooling system. The system accommodates the two SIM cameras with a double-ended conduction bar, a single methane heat pipe, independent turn-off devices, and a flight-like radiator. The turn ]off devices consist of a liquid trap, for removing the methane from the pipe, and an electrical heater to raise the methane temperature above the critical point thus preventing two-phase operation. This is the first time a cryogenic heat pipe has been tested at JPL and is also the first heat pipe to incorporate the turn-off features. Operation at 163K with a methane heat pipe is an important new thermal control capability for the lab. In addition, the two turn-off technologies enhance the "bag of tricks" available to the JPL thermal community. The successful test program brings this heat pipe to a high level of technology readiness.

A Disposable Microfluidic Device for Controlled Drug Release from Thermal-Sensitive Liposomes by High Intensity Focused Ultrasound.

PubMed

Meng, Long; Deng, Zhiting; Niu, Lili; Li, Fei; Yan, Fei; Wu, Junru; Cai, Feiyan; Zheng, Hairong

2015-01-01

The drug release triggered thermally by high intensity focused ultrasound (HIFU) has been considered a promising drug delivery strategy due to its localized energy and non-invasive characters. However, the mechanism underlying the HIFU-mediated drug delivery remains unclear due to its complexity at the cellular level. In this paper, micro-HIFU (MHIFU) generated by a microfluidic device is introduced which is able to control the drug release from temperature-sensitive liposomes (TSL) and evaluate the thermal and mechanical effects of ultrasound on the cellular drug uptake and apoptosis. By simply adjusting the input electrical signal to the device, the temperature of sample can be maintained at 37 °C, 42 °C and 50 °C with the deviation of ± 0.3 °C as desired. The flow cytometry results show that the drug delivery under MHIFU sonication leads to a significant increase in apoptosis compared to the drug release by incubation alone at elevated temperature of 42 °C. Furthermore, increased squamous and protruding structures on the surface membrane of cells were detected by atomic force microscopy (AFM) after MHIFU irradiation of TSL. We demonstrate that compared to the routine HIFU treatment, MHIFU enables monitoring of in situ interactions between the ultrasound and cell in real time. Furthermore, it can quantitatively analyze and characterize the alterations of the cell membrane as a function of the treatment time.

Preliminary design of a radiator shading device for a lunar outpost

NASA Technical Reports Server (NTRS)

Barron, Carlos; Castro, Norma I.; Phillips, Brian

1991-01-01

The National Aeronautics and Space Administration is designing a thermal control system for an outpost to be placed permanently on the Moon. One of the functions of the thermal control system is to reject waste heat, which can be accomplished through a radiator. At the lunar equator and during the lunar midday, an unshaded radiator absorbs more heat than it rejects. This problem can be solved by using a shading device to reduce radiation incident on the radiator. The design team was asked to develop concepts for reducing the radiation incident on the radiator and for deploying the radiator and shade system for a 10 kW and a 25 kW heat rejection system. The design team was also asked to develop the best concepts into preliminary design. From the several alternatives developed by the design team, the best one was selected using a decision matrix. Preliminary design of the best concept include support structure, stress analyses, and thermal performance. In addition, the team developed ideas for removing lunar dust from the shading device. The final design solution consisted of a winged radiator shading system with a rail support structure and a scissors mechanism for deployment. The total radiator area required was calculated to be 389 sq m for the 10 kW heat rejection system and 973 sq m for the 25 kW heat rejection system.

Graphene-coated meshes for electroactive flow control devices utilizing two antagonistic functions of repellency and permeability

PubMed Central

Tabassian, Rassoul; Oh, Jung-Hwan; Kim, Sooyeun; Kim, Donggyu; Ryu, Seunghwa; Cho, Seung-Min; Koratkar, Nikhil; Oh, Il-Kwon

2016-01-01

The wettability of graphene on various substrates has been intensively investigated for practical applications including surgical and medical tools, textiles, water harvesting, self-cleaning, oil spill removal and microfluidic devices. However, most previous studies have been limited to investigating the intrinsic and passive wettability of graphene and graphene hybrid composites. Here, we report the electrowetting of graphene-coated metal meshes for use as electroactive flow control devices, utilizing two antagonistic functions, hydrophobic repellency versus liquid permeability. Graphene coating was able to prevent the thermal oxidation and corrosion problems that plague unprotected metal meshes, while also maintaining its hydrophobicity. The shapes of liquid droplets and the degree of water penetration through the graphene-coated meshes were controlled by electrical stimuli based on the functional control of hydrophobic repellency and liquid permeability. Furthermore, using the graphene-coated metal meshes, we developed two active flow devices demonstrating the dynamic locomotion of water droplets and electroactive flow switching. PMID:27796291

Graphene-coated meshes for electroactive flow control devices utilizing two antagonistic functions of repellency and permeability.

PubMed

Tabassian, Rassoul; Oh, Jung-Hwan; Kim, Sooyeun; Kim, Donggyu; Ryu, Seunghwa; Cho, Seung-Min; Koratkar, Nikhil; Oh, Il-Kwon

2016-10-31

The wettability of graphene on various substrates has been intensively investigated for practical applications including surgical and medical tools, textiles, water harvesting, self-cleaning, oil spill removal and microfluidic devices. However, most previous studies have been limited to investigating the intrinsic and passive wettability of graphene and graphene hybrid composites. Here, we report the electrowetting of graphene-coated metal meshes for use as electroactive flow control devices, utilizing two antagonistic functions, hydrophobic repellency versus liquid permeability. Graphene coating was able to prevent the thermal oxidation and corrosion problems that plague unprotected metal meshes, while also maintaining its hydrophobicity. The shapes of liquid droplets and the degree of water penetration through the graphene-coated meshes were controlled by electrical stimuli based on the functional control of hydrophobic repellency and liquid permeability. Furthermore, using the graphene-coated metal meshes, we developed two active flow devices demonstrating the dynamic locomotion of water droplets and electroactive flow switching.

Advances in Electrically Driven Thermal Management

NASA Technical Reports Server (NTRS)

Didion, Jeffrey R.

2017-01-01

Electrically Driven Thermal Management is a vibrant technology development initiative incorporating ISS based technology demonstrations, development of innovative fluid management techniques and fundamental research efforts. The program emphasizes high temperature high heat flux thermal management required for future generations of RF electronics and power electronic devices. This presentation reviews i.) preliminary results from the Electrohydrodynamic (EHD) Long Term Flight Demonstration launched on STP-H5 payload in February 2017 ii.) advances in liquid phase flow distribution control iii.) development of the Electrically Driven Liquid Film Boiling Experiment under the NASA Microgravity Fluid Physics Program.

Near-field thermal radiation of deep- subwavelength slits in the near infrared range.

PubMed

Guo, Yan; Li, Kuanbiao; Xu, Ying; Wei, Kaihua

2017-09-18

We numerically investigate the thermal radiation of one-dimensional deep subwavelength slits in the near infrared range. Using numerical calculations of single-slit and multi-slit structures, we find that high-level radiation efficiency can be achieved for a wide spectrum when ultra-thin intermediate layers are used, and it is less affected by structure parameters. The underlying mechanisms involve Surface Plasmon Polaritons resonance and Fabry-Perot interference at each slit and the interaction between adjacent slits. This structure helps understand and improve the design of thermal radiation control devices.

Controllable rectification of the axial expansion in the thermally driven artificial muscle

NASA Astrophysics Data System (ADS)

Yue, Donghua; Zhang, Xingyi; Yong, Huadong; Zhou, Jun; Zhou, You-He

2015-09-01

At present, the concept of artificial muscle twisted by polymers or fibers has become a hot issue in the field of intelligent material research according to its distinguishing advantages, e.g., high energy density, large-stroke, non-hysteresis, and inexpensive. The axial thermal expansion coefficient is an important parameter which can affect its demanding applications. In this letter, a device with high accuracy capacitive sensor is constructed to measure the axial thermal expansion coefficient of the twisted carbon fibers and yarns of Kevlar, and a theoretical model based on the thermal elasticity and the geometrical features of the twisted structure are also presented to predict the axial expansion coefficient. It is found that the calculated results take good agreements with the experimental data. According to the present experiment and analyses, a method to control the axial thermal expansion coefficient of artificial muscle is proposed. Moreover, the mechanism of this kind of thermally driven artificial muscle is discussed.

Self-actuating heat switches for redundant refrigeration systems

NASA Technical Reports Server (NTRS)

Chan, Chung K. (Inventor)

1988-01-01

A dual refrigeration system for cooling a sink device is described, which automatically thermally couples the cold refrigerator to the sink device while thermally isolating the warm refrigerator from the sink device. The system includes two gas gap heat switches that each thermally couples one of the refrigerators to the sink device, and a pair of sorption pumps that are coupled through tubes to the heat switches. When the first refrigerator is operated and therefore cold, the first pump which is thermally coupled to it is also cooled and adsorbs gas to withdraw it from the second heat switch, to thereby thermally isolate the sink device from the warm second refrigerator. With the second refrigerator being warm, the second pump is also warm and desorbs gas, so the gas lies in the first switch, to close that switch and therefore thermally couple the cold first refrigerator to the sink device. Thus, the heat switches are automatically switched according to the temperature of the corresponding refrigerator.

Microwave Switching and Attenuation with Superconductors.

NASA Astrophysics Data System (ADS)

Poulin, Grant Darcy

1995-01-01

The discovery of high temperature superconducting (HTS) materials having a critical temperature above the boiling point of liquid nitrogen has generated a large amount of interest in both the basic and applied scientific communities. Considerable research effort has been expended in developing HTS microwave devices, since thin film, passive, microwave components will likely be the first area to be successfully commercialized. This thesis describes a new thin film HTS microwave device that can be operated as a switch or as a continuously variable attenuator. It is well suited for low power analog signal control applications and can easily be integrated with other HTS devices. Due to its small size and mass, the device is expected to find application as a receiver protection switch or as an automatic gain control element, both used in satellite communications receivers. The device has a very low insertion loss, and the isolation in the OFF state is continuously variable to 25 dB. With minor modifications, an isolation exceeding 50 dB is readily achievable. A patent application for the device has been filed, with the patent rights assigned to COM DEV. The device is based on an unusual non-linear response in HTS materials. Under a non-zero DC voltage bias, the current through a superconducting bridge is essentially voltage independent. We have proposed a thermal instability to account for this behaviour. Thermal modelling in conjunction with direct temperature measurements were used to confirm the validity of the model. We have developed a detailed model explaining the microwave response of the device. The model accurately predicts the microwave attenuation as a function of the applied DC control voltage and fully explains the device operation. A key feature is that the device acts as a pure resistive element at microwave frequencies, with no reactance. The resistance is continuously variable, controlled by the DC bias voltage. This distinguishes it from a PIN diode, since PIN diodes have a capacitive reactance that limits their frequency range. Measurements made to confirm the microwave model validity resulted in the development of a new cryogenic de-embedding technique. The technique allows accurate microwave measurements to be made on devices at cryogenic temperatures using only room temperature calibration standards. We have also investigated the effect of kinetic inductance on coplanar waveguide transmission lines, and indicate under what conditions kinetic inductance must be considered in transmission line design.

Non-thermal plasma technologies: new tools for bio-decontamination.

PubMed

Moreau, M; Orange, N; Feuilloley, M G J

2008-01-01

Bacterial control and decontamination are crucial to industrial safety assessments. However, most recently developed materials are not compatible with standard heat sterilization treatments. Advanced oxidation processes, and particularly non-thermal plasmas, are emerging and promising technologies for sanitation because they are both efficient and cheap. The applications of non-thermal plasma to bacterial control remain poorly known for several reasons: this technique was not developed for biological applications and most of the literature is in the fields of physics and chemistry. Moreover, the diversity of the devices and complexity of the plasmas made any general evaluation of the potential of the technique difficult. Finally, no experimental equipment for non-thermal plasma sterilization is commercially available and reference articles for microbiologists are rare. The present review aims to give an overview of the principles of action and applications of plasma technologies in biodecontamination.

Passive temperature control based on a phase change metasurface.

PubMed

Wu, Sheng-Rui; Lai, Kuan-Lin; Wang, Chih-Ming

2018-05-16

In this paper, a tunable mid-infrared metasurface based on VO 2 phase change material is proposed for temperature control. The proposed structure consisting of a VO 2 /SiO 2 /VO 2 cavity supports a thermally switchable Fabry-Perot-like resonance mode at the transparency window of the atmosphere. Theoretically, the radiative cooling power density of the proposed metasurface can be switched to four-fold as the device temperature is below/above the phase change temperature of VO 2 . Besides radiative cooling, a passive temperature control application based on this huge cooling power switching ability is theoretically demonstrated. We believe the proposed device can be applied for small radiative cooling and temperature control applications.

Thermally stable In0.7Ga0.3As/In0.52Al0.48As pHEMTs using thermally evaporated palladium gate metallization

NASA Astrophysics Data System (ADS)

Ian, Ka Wa; Zawawiand, Mohamad Adzhar Md; Missous, Mohamed

2014-03-01

This work described the fabrication and performances of strained channel In0.52Al0.47As/In0.7Ga0.3As/InP pHEMTs with thermally evaporated Pd/Ti/Au gate metallization. The electrical characteristics of these Pd-gate devices are studied to investigate the effects of changing the Pd metal thickness, annealing temperature and annealing time. Following annealing at 200 °C for 35 min, a 10 nm Pd-gate device displays a VTH of -0.25 V, which is significantly smaller compared to those with Ti/Au gate schemes showing VTH = -0.75 V. A 1 um gate length device exhibits an improved Gm of 580 mS mm-1 (from 500 mS mm-1), a high IDSmax of 400 mA mm-1 (from 330 mA mm-1) and good fT and fmax of 24.5 and 49 GHz commensurate with the 1 µm gate length. All these enhancements are attributed to the controllable gate sinking of Pd. The device shows no significant degradation even after annealing at 230 °C for more than 5 h, which implies that the reliability of these Pd-gate structures is excellent.

Collection of low-grade waste heat for enhanced energy harvesting

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dede, Ercan M., E-mail: eric.dede@tema.toyota.com; Schmalenberg, Paul; Wang, Chi-Ming

Enhanced energy harvesting through the collection of low-grade waste heat is experimentally demonstrated. A structural optimization technique is exploited in the design of a thermal-composite substrate to guide and gather the heat emanating from multiple sources to a predetermined location. A thermoelectric generator is then applied at the selected focusing region to convert the resulting low-grade waste heat to electrical power. The thermal characteristics of the device are experimentally verified by direct temperature measurements of the system and numerically validated via heat conduction simulations. Electrical performance under natural and forced convection is measured, and in both cases, the device withmore » optimized heat flow control plus energy harvesting demonstrates increased power generation when compared with a baseline waste heat recovery system. Electronics applications include energy scavenging for autonomously powered sensor networks or self-actuated devices.« less

Thermal management and design for optical refrigeration

NASA Astrophysics Data System (ADS)

Symonds, G.; Farfan, B. G.; Ghasemkhani, M. R.; Albrecht, A. R.; Sheik-Bahae, M.; Epstein, R. I.

2016-03-01

We present our recent work in developing a robust and versatile optical refrigerator. This work focuses on minimizing parasitic energy losses through efficient design and material optimization. The cooler's thermal linkage system and housing are studied using thermal analysis software to minimize thermal gradients through the device. Due to the extreme temperature differences within the device, material selection and characterization are key to constructing an efficient device. We describe the design constraints and material selections necessary for thermally efficient and durable optical refrigeration.

21 CFR 886.5200 - Eyelid thermal pulsation system.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Eyelid thermal pulsation system. 886.5200 Section 886.5200 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Therapeutic Devices § 886.5200 Eyelid thermal pulsation system...

Design of CMOS compatible and compact, thermally-compensated electro-optic modulator based on off-axis microring resonator for dense wavelength division multiplexing applications.

PubMed

Haldar, Raktim; Banik, Abhik D; Varshney, Shailendra K

2014-09-22

In this work, we propose and demonstrate the performance of silicon-on-insulator (SOI) off-axis microring resonator (MRR) as electro-optic modulator (EOM). Adding an extra off-axis inner-ring in conventional microring structure provides control to compensate thermal effects on EOM. It is shown that dynamically controlled bias-voltage applied to the outer ring has the potency to quell the thermal effects over a wide range of temperature. Thus, besides the appositely biased conventional microring, off-axis inner microring with pre-emphasized electrical input message signal enables our proposed structure suitable for high data-rate dense wavelength division multiplexing scheme of optical communication within a very compact device size.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fulkerson, Edward; Lanning, Rodney K.; Telford, Steven

A device includes a u-channel shaped member and a printed circuit board including a plurality of capacitors. Each of the plurality of capacitors has a mounting surface mounted to the printed circuit board and an opposing heat transfer surface thermally coupled to the u-channel shaped member. The device also includes an output cable coupled to the printed circuit board and a return cable coupled to the printed circuit board. The device further includes a control transistor disposed inside the u-channel shaped member and a current sensing resistor disposed inside the u-channel shaped member.

Susceptor heating device for electron beam brazing

DOEpatents

Antieau, Susan M.; Johnson, Robert G. R.

1999-01-01

A brazing device and method are provided which locally apply a controlled amount of heat to a selected area, within a vacuum. The device brazes two components together with a brazing metal. A susceptor plate is placed in thermal contact with one of the components. A serrated pedestal supports the susceptor plate. When the pedestal and susceptor plate are in place, an electron gun irradiates an electron beam at the susceptor plate such that the susceptor plate is sufficiently heated to transfer heat through the one component and melt the brazing metal.

Design, implementation, and extension of thermal invisibility cloaks

NASA Astrophysics Data System (ADS)

Zhang, Youming; Xu, Hongyi; Zhang, Baile

2015-05-01

A thermal invisibility cloak, as inspired by optical invisibility cloaks, is a device which can steer the conductive heat flux around an isolated object without changing the ambient temperature distribution so that the object can be "invisible" to external thermal environment. While designs of thermal invisibility cloaks inherit previous theories from optical cloaks, the uniqueness of heat diffusion leads to more achievable implementations. Thermal invisibility cloaks, as well as the variations including thermal concentrator, rotator, and illusion devices, have potentials to be applied in thermal management, sensing and imaging applications. Here, we review the current knowledge of thermal invisibility cloaks in terms of their design and implementation in cloaking studies, and their extension as other functional devices.

A New Regime of Nanoscale Thermal Transport: Collective Diffusion Increases Dissipation Efficiency

DTIC Science & Technology

2015-04-21

including thermal management in nanoelectronics and optoelectronics, thermoelectric devices, nanoenhanced photovoltaics , and nanoparticle-mediated...applications including thermoelectrics for energyharvesting, nanoparticle-mediated thermal therapy, nano- enhanced photovoltaics , and thermal... thermoelectric devices, nanoparticle- mediated thermal therapies, and nanoenhanced photovoltaics for improving clean-energy technologies. Author contributions

Thermal Strap And Cushion For Thermoelectric Cooler

NASA Technical Reports Server (NTRS)

Jones, Jack A.; Petrick, S. Walter; Bard, Steven

1991-01-01

Inexpensive cushioning strap proposed for use as thermal contact between thermoelectric cooler and device to be cooled, such as laser diode, infrared detector, or charge-coupled device for imaging. Provides high thermal conductance while minimizing thermal and mechanical stresses on thermoelectric cooler. Used as alternative to flexible thermal strap made of silver.

A novel miniaturized PCR multi-reactor array fabricated using flip-chip bonding techniques

NASA Astrophysics Data System (ADS)

Zou, Zhi-Qing; Chen, Xiang; Jin, Qing-Hui; Yang, Meng-Su; Zhao, Jian-Long

2005-08-01

This paper describes a novel miniaturized multi-chamber array capable of high throughput polymerase chain reaction (PCR). The structure of the proposed device is verified by using finite element analysis (FEA) to optimize the thermal performance, and then implemented on a glass-silicon substrate using a standard MEMS process and post-processing. Thermal analysis simulation and verification of each reactor cell is equipped with integrated Pt temperature sensors and heaters at the bottom of the reaction chamber for real-time accurate temperature sensing and control. The micro-chambers are thermally separated from each other, and can be controlled independently. The multi-chip array was packaged on a printed circuit board (PCB) substrate using a conductive polymer flip-chip bonding technique, which enables effective heat dissipation and suppresses thermal crosstalk between the chambers. The designed system has successfully demonstrated a temperature fluctuation of ±0.5 °C during thermal multiplexing of up to 2 × 2 chambers, a full speed of 30 min for 30 cycle PCR, as well as the capability of controlling each chamber digitally and independently.

Thermal management of microwave power heterojunction bipolar transistors

NASA Astrophysics Data System (ADS)

Bozada, C.; Cerny, C.; De Salvo, G.; Dettmer, R.; Ebel, J.; Gillespie, J.; Havasy, C.; Jenkins, T.; Ito, C.; Nakano, K.; Pettiford, C.; Quach, T.; Sewell, J.; Via, G. D.; Anholt, R.

1997-10-01

A comprehensive study of the device layout effects on thermal resistance in thermally-shunted heterojunction bipolar transistors (HBTs) was completed. The thermal resistance scales linearly with emitter dot diameter for single element HBTs. For multiple emitter element devices, the thermal resistance scales with area. HBTs with dot geometrics have lower thermal impedance than bar HBTs with equivalent emitter area. The thermal resistance of a 200 μm 2 emitter area device was reduced from 266°C/W to 146°C/W by increasing the shunt thickness from 3 μm to 20 μm and placing a thermal shunt landing between the fingers. Also, power-added efficiencies at 10 GHz were improved from 30% to 68% by this thermal resistance reduction.

Computer Controlled Portable Greenhouse Climate Control System for Enhanced Energy Efficiency

NASA Astrophysics Data System (ADS)

Datsenko, Anthony; Myer, Steve; Petties, Albert; Hustek, Ryan; Thompson, Mark

2010-04-01

This paper discusses a student project at Kettering University focusing on the design and construction of an energy efficient greenhouse climate control system. In order to maintain acceptable temperatures and stabilize temperature fluctuations in a portable plastic greenhouse economically, a computer controlled climate control system was developed to capture and store thermal energy incident on the structure during daylight periods and release the stored thermal energy during dark periods. The thermal storage mass for the greenhouse system consisted of a water filled base unit. The heat exchanger consisted of a system of PVC tubing. The control system used a programmable LabView computer interface to meet functional specifications that minimized temperature fluctuations and recorded data during operation. The greenhouse was a portable sized unit with a 5' x 5' footprint. Control input sensors were temperature, water level, and humidity sensors and output control devices were fan actuating relays and water fill solenoid valves. A Graphical User Interface was developed to monitor the system, set control parameters, and to provide programmable data recording times and intervals.

Performance of a Water Recirculation Loop Maintenance Device and Process for the Advanced Spacesuit Water Membrane Evaporator

NASA Technical Reports Server (NTRS)

Steele, John W.; Rector, Tony; Bue, Grant C.; Campbell, Colin; Makinen, Janice

2013-01-01

A dual-bed device to maintain the water quality of the Advanced Spacesuit Water Membrane Evaporation (SWME) water recirculation loop has been designed and is undergoing testing. The SWME is a heat rejection device under development at the NASA Johnson Space Center to perform thermal control for advanced spacesuits. One advantage to this technology is the potential for a significantly greater degree of tolerance to contamination when compared to the existing Sublimator technology. The driver for the development of a water recirculation maintenance device is to further enhance this advantage through the leveraging of fluid loop management lessons-learned from the International Space Station (ISS). A bed design that was developed for a Hamilton Sundstrand military application, and considered for a potential ISS application with the Urine Processor Assembly, provides a low pressure drop means for water maintenance in a recirculation loop. The bed design is coupled with high capacity ion exchange resins, organic adsorbents, and a cyclic methodology developed for the Extravehicular Mobility Unit (EMU) Transport Water loop. The bed design further leverages a sorbent developed for ISS that introduces a biocide in a microgravity-compatible manner for the Internal Active Thermal Control System (IATCS). The leveraging of these water maintenance technologies to the SWME recirculation loop is a unique demonstration of applying the valuable lessons learned on the ISS to the next generation of manned spaceflight Environmental Control and Life Support System (ECLSS) hardware.

Design and Evaluation of a Water Recirculation Loop Maintenance Device for the Advanced Spacesuit Water Membrane Evaporator

NASA Technical Reports Server (NTRS)

Steele, John W.; Rector, Tony; Bue, Grant C.; Campbell, Colin; Makinen, Janice

2012-01-01

A dual-bed device to maintain the water quality of the Advanced Spacesuit Water Membrane Evaporation (SWME) water recirculation loop has been designed and is undergoing testing. The SWME is a heat rejection device under development at the NASA Johnson Space Center to perform thermal control for advanced spacesuits. One advantage to this technology is the potential for a significantly greater degree of tolerance to contamination when compared to the existing sublimator technology. The driver for the development of a water recirculation maintenance device is to further enhance this advantage through the leveraging of fluid loop management lessons learned from the International Space Station (ISS). A bed design that was developed for a Hamilton Sundstrand military application, and considered for a potential ISS application with the Urine Processor Assembly, provides a low pressure drop means for water maintenance in a recirculation loop. The bed design is coupled with high-capacity ion exchange resins, organic adsorbents, and a cyclic methodology developed for the Extravehicular Mobility Unit Transport Water Loop. The bed design further leverages a sorbent developed for the ISS that introduces a biocide in a microgravity-compatible manner for the Internal Active Thermal Control System. The leveraging of these water maintenance technologies to the SWME recirculation loop is a unique demonstration of applying the valuable lessons learned on the ISS to the next generation of crewed spaceflight Environmental Control and Life Support System hardware.

Design and Evaluation of a Water Recirculation Loop Maintenance Device for the Advanced Spacesuit Water Membrane Evaporator

NASA Technical Reports Server (NTRS)

Steele, John W.; Rector, Tony; Bue, Grant C.; Campbell, Colin; Makinen, Janice

2011-01-01

A dual-bed device to maintain the water quality of the Advanced Spacesuit Water Membrane Evaporation (SWME) water recirculation loop has been designed and is undergoing testing. The SWME is a heat rejection device under development at the NASA Johnson Space Center to perform thermal control for advanced spacesuits. One advantage to this technology is the potential for a significantly greater degree of tolerance to contamination when compared to the existing Sublimator technology. The driver for the development of a water recirculation maintenance device is to further enhance this advantage through the leveraging of fluid loop management lessons-learned from the International Space Station (ISS). A bed design that was developed for a Hamilton Sundstrand military application, and considered for a potential ISS application with the Urine Processor Assembly, provides a low pressure drop means for water maintenance in a recirculation loop. The bed design is coupled with high capacity ion exchange resins, organic adsorbents, and a cyclic methodology developed for the Extravehicular Mobility Unit (EMU) Transport Water loop. The bed design further leverages a sorbent developed for ISS that introduces a biocide in a microgravity-compatible manner for the Internal Active Thermal Control System (IATCS). The leveraging of these water maintenance technologies to the SWME recirculation loop is a clear demonstration of applying the valuable lessons learned on the ISS to the next generation of manned spaceflight Environmental Control and Life Support System (ECLSS) hardware.

Performance of a Water Recirculation Loop Maintenance Device and Process for the Advanced Spacesuit Water Membrane Evaporator

NASA Technical Reports Server (NTRS)

Rector, Tony; Steele, John W.; Bue, Grant C.; Campbell, Colin; Makinen, Janice

2012-01-01

A water loop maintenance device and process to maintain the water quality of the Advanced Spacesuit Water Membrane Evaporation (SWME) water recirculation loop has been undergoing a performance evaluation. The SWME is a heat rejection device under development at the NASA Johnson Space Center to perform thermal control for advanced spacesuits. One advantage to this technology is the potential for a significantly greater degree of tolerance to contamination when compared to the existing Sublimator technology. The driver for the water recirculation maintenance device and process is to further enhance this advantage through the leveraging of fluid loop management lessons-learned from the International Space Station (ISS). A bed design that was developed for a Hamilton Sundstrand military application, and considered for a potential ISS application with the Urine Processor Assembly, provides a low pressure drop means for water maintenance in a recirculation loop. The bed design is coupled with high capacity ion exchange resins, organic adsorbents, and a cyclic methodology developed for the Extravehicular Mobility Unit (EMU) Transport Water loop. The maintenance process further leverages a sorbent developed for ISS that introduces a biocide in a microgravity-compatible manner for the Internal Active Thermal Control System (IATCS). The leveraging of these water maintenance technologies to the SWME recirculation loop is a unique demonstration of applying the valuable lessons learned on the ISS to the next generation of manned spaceflight Environmental Control and Life Support System (ECLSS) hardware. This

Thermal Emission Control via Bandgap Engineering in Aperiodically Designed Nanophotonic Devices.

PubMed

Maciá, Enrique

2015-05-20

Aperiodic photonic crystals can open up novel routes for more efficient photon management due to increased degrees of freedom in their design along with the unique properties brought about by the long-range aperiodic order as compared to their periodic counterparts. In this work we first describe the fundamental notions underlying the idea of thermal emission/absorption control on the basis of the systematic use of aperiodic multilayer designs in photonic quasicrystals. Then, we illustrate the potential applications of this approach in order to enhance the performance of daytime radiative coolers and solar thermoelectric energy generators.

Thermal Emission Control via Bandgap Engineering in Aperiodically Designed Nanophotonic Devices

PubMed Central

Maciá, Enrique

2015-01-01

Aperiodic photonic crystals can open up novel routes for more efficient photon management due to increased degrees of freedom in their design along with the unique properties brought about by the long-range aperiodic order as compared to their periodic counterparts. In this work we first describe the fundamental notions underlying the idea of thermal emission/absorption control on the basis of the systematic use of aperiodic multilayer designs in photonic quasicrystals. Then, we illustrate the potential applications of this approach in order to enhance the performance of daytime radiative coolers and solar thermoelectric energy generators. PMID:28347037

Multi-cell storage battery

DOEpatents

Brohm, Thomas; Bottcher, Friedhelm

2000-01-01

A multi-cell storage battery, in particular to a lithium storage battery, which contains a temperature control device and in which groups of one or more individual cells arranged alongside one another are separated from one another by a thermally insulating solid layer whose coefficient of thermal conductivity lies between 0.01 and 0.2 W/(m*K), the thermal resistance of the solid layer being greater by at least a factor .lambda. than the thermal resistance of the individual cell. The individual cell is connected, at least in a region free of insulating material, to a heat exchanger, the thermal resistance of the heat exchanger in the direction toward the neighboring cell being selected to be greater by at least a factor .lambda. than the thermal resistance of the individual cell and, in addition, the thermal resistance of the heat exchanger toward the temperature control medium being selected to be smaller by at least a factor of about 10 than the thermal resistance of the individual cell, and .lambda. being the ratio of the energy content of the individual cell to the amount of energy that is needed to trigger a thermally induced cell failure at a defined upper operating temperature limit.

40 CFR 63.5779 - What definitions apply to this subpart?

Code of Federal Regulations, 2012 CFR

2012-07-01

....5779 What definitions apply to this subpart? Terms used in this subpart are defined in the Clean Air Act, in § 63.2, and in this section as follows: Add-on control means an air pollution control device, such as a thermal oxidizer, that reduces pollution in an air stream by destruction or removal before...

40 CFR 63.5779 - What definitions apply to this subpart?

Code of Federal Regulations, 2014 CFR

2014-07-01

....5779 What definitions apply to this subpart? Terms used in this subpart are defined in the Clean Air Act, in § 63.2, and in this section as follows: Add-on control means an air pollution control device, such as a thermal oxidizer, that reduces pollution in an air stream by destruction or removal before...

40 CFR 63.5779 - What definitions apply to this subpart?

Code of Federal Regulations, 2013 CFR

2013-07-01

....5779 What definitions apply to this subpart? Terms used in this subpart are defined in the Clean Air Act, in § 63.2, and in this section as follows: Add-on control means an air pollution control device, such as a thermal oxidizer, that reduces pollution in an air stream by destruction or removal before...

40 CFR Table 1 to Subpart Hhhh of... - Minimum Requirements for Monitoring and Recordkeeping

Code of Federal Regulations, 2010 CFR

2010-07-01

...-hour block averages. 2. Other process or control device parameters specified in your OMM b plan. As... value for each product manufactured during the operating day. 6. UF-to-latex ratio in the binder c For... Required if a thermal oxidizer is used to control formaldehyde emissions. b Required if process...

Methods of measurement for semiconductor materials, process control, and devices

NASA Technical Reports Server (NTRS)

Bullis, W. M. (Editor)

1972-01-01

Activities directed toward the development of methods of measurement for semiconductor materials, process control, and devices are described. Accomplishments include the determination of the reasons for differences in measurements of transistor delay time, identification of an energy level model for gold-doped silicon, and the finding of evidence that it does not appear to be necessary for an ultrasonic bonding tool to grip the wire and move it across the substrate metallization to make the bond. Work is continuing on measurement of resistivity of semiconductor crystals; study of gold-doped silicon; development of the infrared response technique; evaluation of wire bonds and die attachment; measurement of thermal properties of semiconductor devices, delay time, and related carrier transport properties in junction devices, and noise properties of microwave diodes; and characterization of silicon nuclear radiation detectors.

49 CFR 173.65 - Exceptions for Division 1.4G consumer fireworks.

Code of Federal Regulations, 2014 CFR

2014-10-01

...) The device must pass a thermal stability test. The test must be performed by maintaining the device... thermal stability test; (3) The manufacturer of the Division 1.4G consumer firework applies in writing to... thermal stability test; and (iv) Signed certification declaring that the device for which certification is...

49 CFR 173.65 - Exceptions for Division 1.4G consumer fireworks.

Code of Federal Regulations, 2013 CFR

2013-10-01

...) The device must pass a thermal stability test. The test must be performed by maintaining the device... thermal stability test; (3) The manufacturer of the Division 1.4G consumer firework applies in writing to... thermal stability test; and (iv) Signed certification declaring that the device for which certification is...

Solitonic Josephson Thermal Transport

NASA Astrophysics Data System (ADS)

Guarcello, Claudio; Solinas, Paolo; Braggio, Alessandro; Giazotto, Francesco

2018-03-01

We explore the coherent thermal transport sustained by solitons through a long Josephson junction as a thermal gradient across the system is established. We observe that a soliton causes the heat current through the system to increase. Correspondingly, the junction warms up in conjunction with the soliton, with temperature peaks up to, e.g., approximately 56 mK for a realistic Nb-based proposed setup at a bath temperature Tbath=4.2 K . The thermal effects on the dynamics of the soliton are also discussed. Markedly, this system inherits the topological robustness of the solitons. In view of these results, the proposed device can effectively find an application as a superconducting thermal router in which the thermal transport can be locally mastered through solitonic excitations, whose positions can be externally controlled through a magnetic field and a bias current.

A New Cryomacroscope Device (Type III) for Visualization of Physical Events in Cryopreservation with Applications to Vitrification and Synthetic Ice Modulators

PubMed Central

Rabin, Yoed; Taylor, Michael J.; Feig, Justin S. G.; Baicu, Simona; Chen, Zhen

2013-01-01

The objective of the current study is to develop a new cryomacroscope prototype for the study of vitrification in large-size specimens. The unique contribution in the current study is in developing a cryomacroscope setup as an add-on device to a commercial controlled-rate cooler and in demonstration of physical events in cryoprotective cocktails containing synthetic ice modulators (SIM)—compounds which hinder ice crystal growth. Cryopreservation by vitrification is a highly complex application, where the likelihood of crystallization, fracture formation, degradation of the biomaterial quality, and other physical events are dependent not only upon the instantaneous cryogenic conditions, but more significantly upon the evolution of conditions along the cryogenic protocol. Nevertheless, cryopreservation success is most frequently assessed by evaluating the cryopreserved product at its end states—either at the cryogenic storage temperature or room temperature. The cryomacroscope is the only available device for visualization of large-size specimens along the thermal protocol, in an effort to correlate the quality of the cryopreserved product with physical events. Compared with earlier cryomacroscope prototypes, the new Cryomacroscope-III evaluated here benefits from a higher resolution color camera, improved illumination, digital recording capabilities, and high repeatability in tested thermal conditions via a commercial controlled-rate cooler. A specialized software package was developed in the current study, having two modes of operation: (a) experimentation mode to control the operation of the camera, record camera frames sequentially, log thermal data from sensors, and save case-specific information; and (b) post-processing mode to generate a compact file integrating images, elapsed time, and thermal data for each experiment. The benefits of the Cryomacroscope-III are demonstrated using various tested mixtures of SIMs with the cryoprotective cocktail DP6, which were found effective in preventing ice growth, even at significantly subcritical cooling rates with reference to the pure DP6. PMID:23993920

Ultrasonic versus monopolar energy-based surgical devices in terms of surgical smoke and lateral thermal damage (ULMOST): a randomized controlled trial.

PubMed

Choi, Chahien; Do, In-Gu; Song, Taejong

2018-04-09

The purpose of this study was to compare the degree of surgical smoke or vapor and lateral thermal damage caused by two different energy-based surgical devices (ESDs) used in colpotomy during total laparoscopic hysterectomy. Patients undergoing laparoscopic hysterectomy were randomly assigned to an ultrasonic ESD group (n = 20) or monopolar ESD group (n = 20). Colpotomy was performed using the assigned ESD. The degree of surgical smoke or vapor obstructing the laparoscopic view was assessed by two independent reviewers using a 5-point Likert scale, in which a higher score indicates worse visibility. The degree of the lateral thermal damage was measured as the width from the point of instrument application to the margins of the unchanged nearby tissue using a light microscope. The baseline characteristics did not statistically differ between the two groups. The degree of surgical smoke or vapor obstructing vision was 1.2 ± 0.8 points in the ultrasonic group and 3.9 ± 0.7 points in the monopolar groups (p < 0.001). The lateral thermal damage was significantly increased in the monopolar group compared to in the ultrasound group (1500 µm [1200-2500 µm] vs. 950 µm [650-1725 µm], p = 0.037). Ultrasonic ESD had better laparoscopic visibility and caused less lateral thermal damage during colpotomy compared to monopolar device.

Simultaneous control of thermoelectric properties in p- and n-type materials by electric double-layer gating: New design for thermoelectric device

NASA Astrophysics Data System (ADS)

Takayanagi, Ryohei; Fujii, Takenori; Asamitsu, Atsushi

2015-05-01

We report a novel design of a thermoelectric device that can control the thermoelectric properties of p- and n-type materials simultaneously by electric double-layer gating. Here, p-type Cu2O and n-type ZnO were used as the positive and negative electrodes of the electric double-layer capacitor structure. When a gate voltage was applied between the two electrodes, holes and electrons accumulated on the surfaces of Cu2O and ZnO, respectively. The thermopower was measured by applying a thermal gradient along the accumulated layer on the electrodes. We demonstrate here that the accumulated layers worked as a p-n pair of the thermoelectric device.

Bumper wall for plasma device

DOEpatents

Coultas, Thomas A.

1977-01-01

Operation of a plasma device such as a reactor for controlled thermonuclear fusion is facilitated by an improved bumper wall enclosing the plasma to smooth the flow of energy from the plasma as the energy impinges upon the bumper wall. The bumper wall is flexible to withstand unequal and severe thermal shocks and it is readily replaced at less expense than the cost of replacing structural material in the first wall and blanket that surround it.

Photopolymerizable liquid encapsulants for microelectronic devices

NASA Astrophysics Data System (ADS)

Baikerikar, Kiran K.

2000-10-01

Plastic encapsulated microelectronic devices consist of a silicon chip that is physically attached to a leadframe, electrically interconnected to input-output leads, and molded in a plastic that is in direct contact with the chip, leadframe, and interconnects. The plastic is often referred to as the molding compound, and is used to protect the chip from adverse mechanical, thermal, chemical, and electrical environments. Encapsulation of microelectronic devices is typically accomplished using a transfer molding process in which the molding compound is cured by heat. Most transfer molding processes suffer from significant problems arising from the high operating temperatures and pressures required to fill the mold. These aspects of the current process can lead to thermal stresses, incomplete mold filling, and wire sweep. In this research, a new strategy for encapsulating microelectronic devices using photopolymerizable liquid encapsulants (PLEs) has been investigated. The PLEs consist of an epoxy novolac-based vinyl ester resin (˜25 wt.%), fused silica filler (70--74 wt.%), and a photoinitiator, thermal initiator, and silane coupling agent. For these encapsulants, the use of light, rather than heat, to initiate the polymerization allows precise control over when the reaction starts, and therefore completely decouples the mold filling and the cure. The low viscosity of the PLEs allows for low operating pressures and minimizes problems associated with wire sweep. In addition, the in-mold cure time for the PLEs is equivalent to the in-mold cure times of current transfer molding compounds. In this thesis, the thermal and mechanical properties, as well as the viscosity and adhesion of photopolymerizable liquid encapsulants, are reported in order to demonstrate that a UV-curable formulation can have the material properties necessary for microelectronic encapsulation. In addition, the effects of the illumination time, postcure time, fused silica loading, and the inclusion of a thermal initiator on the thermal and mechanical properties of the final cured encapsulants have been investigated. The results show that the material properties of the PLEs are the same, if not better, than those exhibited by conventional transfer molding compounds and demonstrate the potential of using PLEs for encapsulating microelectronic devices.

Nickel-Graphite Composite Compliant Interface and/or Hot Shoe Material

NASA Technical Reports Server (NTRS)

Firdosy, Samad A.; Chun-Yip Li, Billy; Ravi, Vilupanur A.; Fleurial, Jean-Pierre; Caillat, Thierry; Anjunyan, Harut

2013-01-01

Next-generation high-temperature thermoelectric-power-generating devices will employ segmented architectures and will have to reliably withstand thermally induced mechanical stresses produced during component fabrication, device assembly, and operation. Thermoelectric materials have typically poor mechanical strength, exhibit brittle behavior, and possess a wide range of coefficient of thermal expansion (CTE) values. As a result, the direct bonding at elevated temperatures of these materials to each other to produce segmented leg components is difficult, and often results in localized microcracking at interfaces and mec hanical failure due to the stresses that arise from the CTE mismatch between the various materials. Even in the absence of full mechanical failure, degraded interfaces can lead to increased electrical and thermal resistances, which adversely impact conversion efficiency and power output. The proposed solution is the insertion of a mechanically compliant layer, with high electrical and thermal conductivity, between the low- and high-temperature segments to relieve thermomechanical stresses during device fabrication and operation. This composite material can be used as a stress-relieving layer between the thermoelectric segments and/or between a thermoelectric segment and a hot- or cold-side interconnect material. The material also can be used as a compliant hot shoe. Nickel-coated graphite powders were hot-pressed to form a nickel-graphite composite material. A freestanding thermoelectric segmented leg was fabricated by brazing the compliant pad layer between the high-temperature p- Zintl and low-temperature p-SKD TE segments using Cu-Ag braze foils. The segmented leg stack was heated in vacuum under a compressive load to achieve bonding. The novelty of the innovation is the use of composite material that re duces the thermomechanical stresses en - countered in the construction of high-efficiency, high-temperature therm - o-electric devices. The compliant pad enables the bonding of dissimilar thermoelectric materials while maintaining the desired electrical and thermal properties essential for efficient device operation. The modulus, CTE, electrical, and thermal conductances of the composite can be controlled by varying the ratio of nickel to graphite.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Spong, D.A.; Hirshman, S.P.; Whitson, J.C.

A new class of low aspect ratio toroidal hybrid stellarators is found using more general plasma confinement optimization criterion than quasi-symmetrization. The plasma current profile and shape of the outer magnetic flux surface are used as control variables to achieve near constancy of the longitudinal invariant J* on internal flux surfaces (quasi-omnigeneity), in addition to a number of other desirable physics target properties. We find that a range of compact (small aspect ratio A), high {beta} (ratio of thermal energy to magnetic field energy), low plasma current devices exist which have significantly improved confinement both for thermal as well asmore » energetic (collisionless) particle components. With reasonable increases in magnetic field and geometric size, such devices can also be scaled to confine 3.5 MeV alpha particle orbits.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moreno, Gilbert

The objective for this project is to develop thermal management strategies to enable efficient and high-temperature wide-bandgap (WBG)-based power electronic systems (e.g., emerging inverter and DC-DC converter). Device- and system-level thermal analyses are conducted to determine the thermal limitations of current automotive power modules under elevated device temperature conditions. Additionally, novel cooling concepts and material selection will be evaluated to enable high-temperature silicon and WBG devices in power electronics components. WBG devices (silicon carbide [SiC], gallium nitride [GaN]) promise to increase efficiency, but will be driven as hard as possible. This creates challenges for thermal management and reliability.

Prognostics of Power Mosfets Under Thermal Stress Accelerated Aging Using Data-Driven and Model-Based Methodologies

NASA Technical Reports Server (NTRS)

Celaya, Jose; Saxena, Abhinav; Saha, Sankalita; Goebel, Kai F.

2011-01-01

An approach for predicting remaining useful life of power MOSFETs (metal oxide field effect transistor) devices has been developed. Power MOSFETs are semiconductor switching devices that are instrumental in electronics equipment such as those used in operation and control of modern aircraft and spacecraft. The MOSFETs examined here were aged under thermal overstress in a controlled experiment and continuous performance degradation data were collected from the accelerated aging experiment. Dieattach degradation was determined to be the primary failure mode. The collected run-to-failure data were analyzed and it was revealed that ON-state resistance increased as die-attach degraded under high thermal stresses. Results from finite element simulation analysis support the observations from the experimental data. Data-driven and model based prognostics algorithms were investigated where ON-state resistance was used as the primary precursor of failure feature. A Gaussian process regression algorithm was explored as an example for a data-driven technique and an extended Kalman filter and a particle filter were used as examples for model-based techniques. Both methods were able to provide valid results. Prognostic performance metrics were employed to evaluate and compare the algorithms.

Air-coupled acoustic thermography for in-situ evaluation

NASA Technical Reports Server (NTRS)

Zalameda, Joseph N. (Inventor); Winfree, William P. (Inventor); Yost, William T. (Inventor)

2010-01-01

Acoustic thermography uses a housing configured for thermal, acoustic and infrared radiation shielding. For in-situ applications, the housing has an open side adapted to be sealingly coupled to a surface region of a structure such that an enclosed chamber filled with air is defined. One or more acoustic sources are positioned to direct acoustic waves through the air in the enclosed chamber and towards the surface region. To activate and control each acoustic source, a pulsed signal is applied thereto. An infrared imager focused on the surface region detects a thermal image of the surface region. A data capture device records the thermal image in synchronicity with each pulse of the pulsed signal such that a time series of thermal images is generated. For enhanced sensitivity and/or repeatability, sound and/or vibrations at the surface region can be used in feedback control of the pulsed signal applied to the acoustic sources.

System and method of providing quick thermal comfort with reduced energy by using directed spot conditioning

DOEpatents

Wang, Mingyu; Kadle, Prasad S.; Ghosh, Debashis; Zima, Mark J.; Wolfe, IV, Edward; Craig, Timothy D

2016-10-04

A heating, ventilation, and air conditioning (HVAC) system and a method of controlling a HVAC system that is configured to provide a perceived comfortable ambient environment to an occupant seated in a vehicle cabin. The system includes a nozzle configured to direct an air stream from the HVAC system to the location of a thermally sensitive portion of the body of the occupant. The system also includes a controller configured to determine an air stream temperature and an air stream flow rate necessary to establish the desired heat supply rate for the sensitive portion and provide a comfortable thermal environment by thermally isolating the occupant from the ambient vehicle cabin temperature. The system may include a sensor to determine the location of the sensitive portion. The nozzle may include a thermoelectric device to heat or cool the air stream.

Thermal control unit for long-time survival of scientific instruments on lunar surface

NASA Astrophysics Data System (ADS)

Ogawa, Kazunori; Iijima, Yuichi; Tanaka, Satoshi

A thermal control unit (lunar survival module) is being developed for scientific instruments placed on the lunar surface. This unit is designed to be used on the future Japanese lunar landing mission SELENE-2. The lunar surface is a severe environment for scientific instruments. The absence of convective cooling by an atmosphere makes the ground surface temperature variable in the wide range of -200 to 100 degC, an environment in which space electronics can hardly survive. The surface elements must have a thermal control structure to maintain the inner temperature within the operable ranges of the instruments for long-time measurements, such as 1 month or longer beyond the lunar nights. The objectives of this study are to develop a thermal control unit for the SELENE-2 mission. So far, we conducted the concept design of the lunar survival module, and estimated its potential by a thermal mathematical model on the assumption of using a lunar seismometer designed for SELENE-2. The basic structure of the thermal module is rather simple in that a heat insulating shell covers the scientific instruments. The concept is that the conical insulator retains heat in the regolith soil in the daylight, and it can keep the device warm in the night. Results of the model calculations indicated the high potential of long-time survival. A bread board model (BBM) was manufactured, and its thermal-vacuum tests were conducted in order to estimate the validity of some thermal parameters assumed in the computed thermal model. The thermal condition of the lunar surface was simulated by glass beads paved in a vacuum chamber, and a temperature-controlled container. Temperature variations of the BBM in thermal cycling tests were compared to a thermal mathematical model, and the thermal parameters were finally assessed. Feeding the test results back into the thermal model for the lunar surface, some thermal parameters were updated but there was no critical effect on the survivability. The experimental results indicated a sufficient survivability potential of the concept of our thermal control system.

Negative Thermal Expansion and Ferroelectric Oxides in Electronic Device Composites

NASA Astrophysics Data System (ADS)

Trujillo, Joy Elizabeth

Electronic devices increasingly pervade our daily lives, driving the need to develop components which have material properties that can be designed to target a specific need. The principle motive of this thesis is to investigate the effects of particle size and composition on three oxides which possess electronic and thermal properties essential to designing improved ceramic composites for more efficient, high energy storage devices. A metal matrix composite project used the negative thermal expansion oxide, ZrW2O 8, to offset the high thermal expansion of the metal matrix without sacrificing high thermal conductivity. Composite preparation employed a powder mixing technique to achieve easy composition control and homogenous phase distribution in order to build composites which target a specific coefficient of thermal expansion (CTE). A tailorable CTE material is desirable for overcoming thermomechanical failure in heat sinks or device casings. This thesis also considers the particle size effect on dielectric properties in a common ferroelectric perovskite, Ba1-xSrxTiO 3. By varying the Ba:Sr ratio, the Curie temperature can be adjusted and by reducing the particle size, the dielectric constant can be increased and hysteresis decreased. These conditions could yield anonymously large dielectric constants near room temperature. However, the ferroelectric behavior has been observed to cease below a minimum size of a few tens of nanometers in bulk or thin film materials. Using a new particle slurry approach, electrochemical impedance spectroscopy allows dielectric properties to be determined for nanoparticles, as opposed to conventional methods which measure only bulk or thin film dielectric properties. In this manner, Ba1-xSrxTiO3 was investigated in a new size regime, extending the theory on the ferroelectric behavior to < 10 nm diameter. This knowledge will improve the potential to incorporate high dielectric constant, low loss ferroelectric nanoparticles in many complex composites. Finally, powder composite processing and impedance spectroscopy techniques were combined to investigate the SrTiO3/(Y2O3) x(ZrO2)1-x (STO/YSZ) oxide system. Thin film heterostructures of STO/YSZ are used in electrochemical energy devices due to their enhanced interfacial ionic conductivity. This work investigated whether this ionic conductivity enhancement could be observed in bulk sintered architectures, which may lead to new device designs for energy storage needs.

Thermal modeling of wide bandgap semiconductor devices for high frequency power converters

NASA Astrophysics Data System (ADS)

Sharath Sundar Ram, S.; Vijayakumari, A.

2018-02-01

The emergence of wide bandgap semiconductors has led to development of new generation semiconductor switches that are highly efficient and scalable. To exploit the advantages of GaNFETs in power converters, in terms of reduction in the size of heat sinks and filters, a thorough understanding of the thermal behavior of the device is essential. This paper aims to establish a thermal model for wideband gap semiconductor GaNFETs commercially available, which will enable power electronic designers to obtain the thermal characteristics of the device more effectively. The model parameters is obtained from the manufacturer’s data sheet by adopting an exponential curve fitting technique and the thermal model is validated using PSPICE simulations. The model was developed based on the parametric equivalence that exists between the thermal and electrical components, such that it responds for transient thermal stresses. A suitable power profile has been generated to evaluate the GaNFET model under different power dissipation scenarios. The results were compared with a Silicon MOSFETs to further highlight the advantages of the GaN devices. The proposed modeling approach can be extended for other GaN devices and can provide a platform for the thermal study and heat sink optimization.

Spatial and temporal control of thermal waves by using DMDs for interference based crack detection

NASA Astrophysics Data System (ADS)

Thiel, Erik; Kreutzbruck, Marc; Ziegler, Mathias

2016-02-01

Active Thermography is a well-established non-destructive testing method and used to detect cracks, voids or material inhomogeneities. It is based on applying thermal energy to a samples' surface whereas inner defects alter the nonstationary heat flow. Conventional excitation of a sample is hereby done spatially, either planar (e.g. using a lamp) or local (e.g. using a focused laser) and temporally, either pulsed or periodical. In this work we combine a high power laser with a Digital Micromirror Device (DMD) allowing us to merge all degrees of freedom to a spatially and temporally controlled heat source. This enables us to exploit the possibilities of coherent thermal wave shaping. Exciting periodically while controlling at the same time phase and amplitude of the illumination source induces - via absorption at the sample's surface - a defined thermal wave propagation through a sample. That means thermal waves can be controlled almost like acoustical or optical waves. However, in contrast to optical or acoustical waves, thermal waves are highly damped due to the diffusive character of the thermal heat flow and therefore limited in penetration depth in relation to the achievable resolution. Nevertheless, the coherence length of thermal waves can be chosen in the mmrange for modulation frequencies below 10 Hz which is perfectly met by DMD technology. This approach gives us the opportunity to transfer known technologies from wave shaping techniques to thermography methods. We will present experiments on spatial and temporal wave shaping, demonstrating interference based crack detection.

Automated software to determine thermal diffusivity of oilgas mixture

NASA Astrophysics Data System (ADS)

Khismatullin, A. S.

2018-05-01

The paper presents automated software to determine thermal diffusivity of oil-gas mixture. A series of laboratory testscovering transformer oil cooling in a power transformer tank was conducted. The paper also describes diagrams of temperature-timedependence of bubbling. Thermal diffusivity coefficients are experimentally defined. The paper considers a mathematical task of heat flowdistribution in a rectangular parallelepiped, alongside with the solution of heat a conduction equation in a power transformer tank, which represents a rectangular parallelepiped. A device for temperature monitoring in the tank is described in detail. The relay control diagram, which ensures temperature monitoring againsttransformer overheating is described.

Development and characterization of a microheater array device for real-time DNA mutation detection

NASA Astrophysics Data System (ADS)

Williams, Layne; Okandan, Murat; Chagovetz, Alex; Blair, Steve

2008-04-01

DNA analysis, specifically single nucleotide polymorphism (SNP) detection, is becoming increasingly important in rapid diagnostics and disease detection. Temperature is often controlled to help speed reaction rates and perform melting of hybridized oligonucleotides. The difference in melting temperatures, Tm, between wild-type and SNP sequences, respectively, to a given probe oligonucleotide, is indicative of the specificity of the reaction. We have characterized Tm's in solution and on a solid substrate of three sequences from known mutations associated with Cystic Fibrosis. Taking advantage of Tm differences, a microheater array device was designed to enable individual temperature control of up to 18 specific hybridization events. The device was fabricated at Sandia National Laboratories using surface micromachining techniques. The microheaters have been characterized using an IR camera at Sandia and show individual temperature control with minimal thermal cross talk. Development of the device as a real-time DNA detection platform, including surface chemistry and associated microfluidics, is described.

Development and characterization of a microheater array device for real-time DNA mutation detection

NASA Astrophysics Data System (ADS)

Williams, Layne; Okandan, Murat; Chagovetz, Alex; Blair, Steve

2008-02-01

DNA analysis, specifically single nucleotide polymorphism (SNP) detection, is becoming increasingly important in rapid diagnostics and disease detection. Temperature is often controlled to help speed reaction rates and perform melting of hybridized oligonucleotides. The difference in melting temperatures, Tm, between wild-type and SNP sequences, respectively, to a given probe oligonucleotide, is indicative of the specificity of the reaction. We have characterized Tm's in solution and on a solid substrate of three sequences from known mutations associated with Cystic Fibrosis. Taking advantage of Tm differences, a microheater array device was designed to enable individual temperature control of up to 18 specific hybridization events. The device was fabricated at Sandia National Laboratories using surface micromachining techniques. The microheaters have been characterized using an IR camera at Sandia and show individual temperature control with minimal thermal cross talk. Development of the device as a real-time DNA detection platform, including surface chemistry and associated microfluidics, is described.

Power Electronics Thermal Management Research: Annual Progress Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moreno, Gilberto

The objective for this project is to develop thermal management strategies to enable efficient and high-temperature wide-bandgap (WBG)-based power electronic systems (e.g., emerging inverter and DC-DC converter). Reliable WBG devices are capable of operating at elevated temperatures (≥ 175 °Celsius). However, packaging WBG devices within an automotive inverter and operating them at higher junction temperatures will expose other system components (e.g., capacitors and electrical boards) to temperatures that may exceed their safe operating limits. This creates challenges for thermal management and reliability. In this project, system-level thermal analyses are conducted to determine the effect of elevated device temperatures on invertermore » components. Thermal modeling work is then conducted to evaluate various thermal management strategies that will enable the use of highly efficient WBG devices with automotive power electronic systems.« less

Controllable Thermal Rectification Realized in Binary Phase Change Composites

PubMed Central

Chen, Renjie; Cui, Yalong; Tian, He; Yao, Ruimin; Liu, Zhenpu; Shu, Yi; Li, Cheng; Yang, Yi; Ren, Tianling; Zhang, Gang; Zou, Ruqiang

2015-01-01

Phase transition is a natural phenomenon happened around our daily life, represented by the process from ice to water. While melting and solidifying at a certain temperature, a high heat of fusion is accompanied, classified as the latent heat. Phase change material (PCM) has been widely applied to store and release large amount of energy attributed to the distinctive thermal behavior. Here, with the help of nanoporous materials, we introduce a general strategy to achieve the binary eicosane/PEG4000 stuffed reduced graphene oxide aerogels, which has two ends with different melting points. It's successfully demonstrated this binary PCM composites exhibits thermal rectification characteristic. Partial phase transitions within porous networks instantaneously result in one end of the thermal conductivity saltation at a critical temperature, and therefore switch on or off the thermal rectification with the coefficient up to 1.23. This value can be further raised by adjusting the loading content of PCM. The uniqueness of this device lies in its performance as a normal thermal conductor at low temperature, only exhibiting rectification phenomenon when temperature is higher than a critical value. The stated technology has broad applications for thermal energy control in macroscopic scale such as energy-efficiency building or nanodevice thermal management. PMID:25748640

Controllable Thermal Rectification Realized in Binary Phase Change Composites

NASA Astrophysics Data System (ADS)

Chen, Renjie; Cui, Yalong; Tian, He; Yao, Ruimin; Liu, Zhenpu; Shu, Yi; Li, Cheng; Yang, Yi; Ren, Tianling; Zhang, Gang; Zou, Ruqiang

2015-03-01

Phase transition is a natural phenomenon happened around our daily life, represented by the process from ice to water. While melting and solidifying at a certain temperature, a high heat of fusion is accompanied, classified as the latent heat. Phase change material (PCM) has been widely applied to store and release large amount of energy attributed to the distinctive thermal behavior. Here, with the help of nanoporous materials, we introduce a general strategy to achieve the binary eicosane/PEG4000 stuffed reduced graphene oxide aerogels, which has two ends with different melting points. It's successfully demonstrated this binary PCM composites exhibits thermal rectification characteristic. Partial phase transitions within porous networks instantaneously result in one end of the thermal conductivity saltation at a critical temperature, and therefore switch on or off the thermal rectification with the coefficient up to 1.23. This value can be further raised by adjusting the loading content of PCM. The uniqueness of this device lies in its performance as a normal thermal conductor at low temperature, only exhibiting rectification phenomenon when temperature is higher than a critical value. The stated technology has broad applications for thermal energy control in macroscopic scale such as energy-efficiency building or nanodevice thermal management.

Thermal transistor utilizing gas-liquid transition.

PubMed

Komatsu, Teruhisa S; Ito, Nobuyasu

2011-01-01

We propose a simple thermal transistor, a device to control heat current. In order to effectively change the current, we utilize the gas-liquid transition of the heat-conducting medium (fluid) because the gas region can act as a good thermal insulator. The three terminals of the transistor are located at both ends and the center of the system, and are put into contact with distinct heat baths. The key idea is a special arrangement of the three terminals. The temperature at one end (the gate temperature) is used as an input signal to control the heat current between the center (source, hot) and another end (drain, cold). Simulating the nanoscale systems of this transistor, control of heat current is demonstrated. The heat current is effectively cut off when the gate temperature is cold and it flows normally when it is hot. By using an extended version of this transistor, we also simulate a primitive application for an inverter.

Thermal Control Utilizing an Thermal Control Utilizing an Two-Phase Loop with High Heat Flux Source

NASA Technical Reports Server (NTRS)

Jeong, Seong-Il; Didion, Jeffrey

2004-01-01

The electric field applied in dielectric fluids causes an imbalance in the dissociation-recombination reaction generated free space charges. The generated charges are redistributed by the applied electric field resulting in the heterocharge layers in the Vicinity of the electrodes. Proper design of the electrodes generates net axial flow motion pumping the fluid. The electrohydrodynamic (EHD) conduction pump is a new device that pumps dielectric fluids utilizing heterocharge layers formed by imposition of electrostatic fields. This paper evaluates the experimental performance of a two-phase breadboard thermal control loop consisting of an EHD conduction pump, condenser, pre-heater, high heat flux evaporator (HE), transport lines, and reservoir (accumulator). The generated pressure head and the maximum applicable heat flux are experimentally determined at various applied voltages and sink temperatures. Recovery from dryout condition by increasing the applied voltage to the pump is also demonstrated.

Athermal silicon optical add-drop multiplexers based on thermo-optic coefficient tuning of sol-gel material.

PubMed

Namnabat, Soha; Kim, Kyung-Jo; Jones, Adam; Himmelhuber, Roland; DeRose, Christopher T; Trotter, Douglas C; Starbuck, Andrew L; Pomerene, Andrew; Lentine, Anthony L; Norwood, Robert A

2017-09-04

Silicon photonics has gained interest for its potential to provide higher efficiency, bandwidth and reduced power consumption compared to electrical interconnects in datacenters and high performance computing environments. However, it is well known that silicon photonic devices suffer from temperature fluctuations due to silicon's high thermo-optic coefficient and therefore, temperature control in many applications is required. Here we present an athermal optical add-drop multiplexer fabricated from ring resonators. We used a sol-gel inorganic-organic hybrid material as an alternative to previously used materials such as polymers and titanium dioxide. In this work we studied the thermal curing parameters of the sol-gel and their effect on thermal wavelength shift of the rings. With this method, we were able to demonstrate a thermal shift down to -6.8 pm/°C for transverse electric (TE) polarization in ring resonators with waveguide widths of 325 nm when the sol-gel was cured at 130°C for 10.5 hours. We also achieved thermal shifts below 1 pm/°C for transverse magnetic (TM) polarization in the C band under different curing conditions. Curing time compared to curing temperature shows to be the most important factor to control sol-gel's thermo-optic value in order to obtain an athermal device in a wide temperature range.

A thermally self-sustained micro-power plant with integrated micro-solid oxide fuel cells, micro-reformer and functional micro-fluidic carrier

NASA Astrophysics Data System (ADS)

Scherrer, Barbara; Evans, Anna; Santis-Alvarez, Alejandro J.; Jiang, Bo; Martynczuk, Julia; Galinski, Henning; Nabavi, Majid; Prestat, Michel; Tölke, René; Bieberle-Hütter, Anja; Poulikakos, Dimos; Muralt, Paul; Niedermann, Philippe; Dommann, Alex; Maeder, Thomas; Heeb, Peter; Straessle, Valentin; Muller, Claude; Gauckler, Ludwig J.

2014-07-01

Low temperature micro-solid oxide fuel cell (micro-SOFC) systems are an attractive alternative power source for small-size portable electronic devices due to their high energy efficiency and density. Here, we report on a thermally self-sustainable reformer-micro-SOFC assembly. The device consists of a micro-reformer bonded to a silicon chip containing 30 micro-SOFC membranes and a functional glass carrier with gas channels and screen-printed heaters for start-up. Thermal independence of the device from the externally powered heater is achieved by exothermic reforming reactions above 470 °C. The reforming reaction and the fuel gas flow rate of the n-butane/air gas mixture controls the operation temperature and gas composition on the micro-SOFC membrane. In the temperature range between 505 °C and 570 °C, the gas composition after the micro-reformer consists of 12 vol.% to 28 vol.% H2. An open-circuit voltage of 1.0 V and maximum power density of 47 mW cm-2 at 565 °C is achieved with the on-chip produced hydrogen at the micro-SOFC membranes.

Development of automotive battery systems capable of surviving modern underhood environments

NASA Astrophysics Data System (ADS)

Pierson, John R.; Johnson, Richard T.

The starting, lighting, and ignition (SLI) battery in today's automobile typically finds itself in an engine compartment that is jammed with mechanical, electrical, and electronic devices. The spacing of these devices precludes air movement and, thus, heat transfer out of the compartment. Furthermore, many of the devices, in addition to the internal combustion engine, actually generate heat. The resulting underhood environment is extremely hostile to thermally-sensitive components, especially the battery. All indications point to a continuation of this trend towards higher engine-compartment temperatures as future vehicles evolve. The impact of ambient temperature on battery life is clearly demonstrated in the failure-mode analysis conducted by the Battery Council International in 1990. This study, when combined with additional failure-mode analyses, vehicle systems simulation, and elevated temperature life testing, provides insight into the potential for extension of life of batteries. Controlled fleet and field tests are used to document and quantify improvements in product design. Three approaches to battery life extension under adverse thermal conditions are assessed, namely: (i) battery design; (ii) thermal management, and (iii) alternative battery locations. The advantages and disadvantages of these approaches (both individually and in combination) for original equipment and aftermarket applications are explored.

Design and analysis of multifunctional structures for embedded electronics in unmanned aerial vehicles

NASA Astrophysics Data System (ADS)

Kothari, Rushabh M.

Multifunctional structures are a new trend in the aerospace industry for the next generation structural design. Many future structures are expected to be something in addition to a load bearing structure. The design and analysis of multifunctional structures combining structural, electrical and thermal functionalities are presented here. The sandwich beam is considered as a starting point for the load bearing structure and then it is modified with a cavity to embed avionics and thermal controls. The embedded avionics inside the load bearing structure would allow weight reduction of the aerospace vehicle due to elimination of separate electronics housing, interconnects, cables etc. The cavity reduces strength of the structure so various reinforcements methods are evaluated. The result of various reinforcements and their effectiveness are presented. The current generation of electronics produce massive amount of heat. In the case of embedded electronics, the excessive heat presents a major challenge to the structural and heat transfer engineers. The embedded nature of electronics prevents the use of the classical heat dissipative methods such as fans and high velocity air flows, etc. The integrated thermal control of the electronics has been designed using passive heat transfer device and highly optimized particulate composite thermal interface material (TIM). The TIMs are used to fill the air gaps and reduce contact resistance between two surfaces, such as electronics and heat dissipators. The efficiency of TIM directly affects the overall heat transfer ability of the integrated thermal control system. The effect of the particles at micron and nano scales are studied for the particulate composite TIM. The thermal boundary resistance study for the particulate composite TIM with nano silica particles is presented in this thesis. The FEA analysis is used to model thermal boundary resistance and compared with the theoretical micromechanics model. The heat pipes are chosen as a part of passive heat transfer device due to their durability and excellent thermal conductivities. The multifunctional system consisting of all above components is modeled for unmanned aerial vehicle (UAV) at subsonic air speeds to demonstrate the validity of the design.

Evaluation of the ruggedness of power DMOS transistor from electro-thermal simulation of UIS behaviour

NASA Astrophysics Data System (ADS)

Donoval, Daniel; Vrbicky, Andrej; Marek, Juraj; Chvala, Ales; Beno, Peter

2008-06-01

High-voltage power MOSFETs have been widely used in switching mode power supply circuits as output drivers for industrial and automotive electronic control systems. However, as the device size is reduced, the energy handling capability is becoming a very important issue to be addressed together with the trade-off between the series on-resistance RON and breakdown voltage VBR. Unclamped inductive switching (UIS) condition represents the circuit switching operation for evaluating the "ruggedness", which characterizes the device capability to handle high avalanche currents during the applied stress. In this paper we present an experimental method which modifies the standard UIS test and allows extraction of the maximum device temperature after the applied standard stress pulse vanishes. Corresponding analysis and non-destructive prediction of the ruggedness of power DMOSFETs devices supported by advanced 2-D mixed mode electro-thermal device and circuit simulation under UIS conditions using calibrated physical models is provided also. The results of numerical simulation are in a very good correlation with experimental characteristics and contribute to their physical interpretation by identification of the mechanism of heat generation and heat source location and continuous temperature extraction.

Apparatus and method of direct water cooling several parallel circuit cards each containing several chip packages

DOEpatents

Cipolla, Thomas M [Katonah, NY; Colgan, Evan George [Chestnut Ridge, NY; Coteus, Paul W [Yorktown Heights, NY; Hall, Shawn Anthony [Pleasantville, NY; Tian, Shurong [Mount Kisco, NY

2011-12-20

A cooling apparatus, system and like method for an electronic device includes a plurality of heat producing electronic devices affixed to a wiring substrate. A plurality of heat transfer assemblies each include heat spreaders and thermally communicate with the heat producing electronic devices for transferring heat from the heat producing electronic devices to the heat transfer assemblies. The plurality of heat producing electronic devices and respective heat transfer assemblies are positioned on the wiring substrate having the regions overlapping. A heat conduit thermally communicates with the heat transfer assemblies. The heat conduit circulates thermally conductive fluid therethrough in a closed loop for transferring heat to the fluid from the heat transfer assemblies via the heat spreader. A thermally conductive support structure supports the heat conduit and thermally communicates with the heat transfer assemblies via the heat spreader transferring heat to the fluid of the heat conduit from the support structure.

NASA Tech Briefs, November 1995. Volume 19, No. 11

NASA Technical Reports Server (NTRS)

1995-01-01

The contents include: 1) Mission Accomplished; 2) Resource Report: Marshall Space Flight Center; 3) NASA 1995 Software of the Year Award; 4) Microbolometers Based on Epitaxial YBa2Cu3O(sub 7-x) Thin Films; 5) Garnet Random-Access Memory; 6) Fabrication of SNS Weak Links on SOS Substrates; 7) High-Voltage MOSFET Switching Circuit; 8) Asymmetric Switching for a PWM H-Bridge Power Circuit; 9) Better Ohmic Contacts for InP Semiconductor Devices; 10) Low-Bandgap Thermovoltaic Materials and Devices; 11) Digital Frequency-Differencing Circuit; 12) Imaging Magnetometer; 13) Computer-Assisted Monitoring of a Complex System; 14) Buffered Telemetry Demodulator; 15) Compact Multifunction Inspection Head; 16) Optical Detection of Fractures in Ceramic Diaphragms; 17) Eddy-Current Detection of Cracks in Reinforced Carbon/Carbon; 18) Apparent Thermal Conductivity of Multilayer Insulation; 19) Optimizing Misch-Metal Compositions in Metal Hydride Anodes; 20) Device for Sampling Surface Contamination; 21) Probabilistic Failure Assessment for Fatigue; 22) Probabilistic Fatigue and Flaw-Propagation Analysis; 23) Windows Program for Driving the TDU-850 Printer; 24) Subband/Transform MATLAB Functions for Processing Images; 25) Computing Equilibrium Chemical Compositions; 26) Program Processes Thermocouple Readings; 27) ICAN-Second-Generation Integrated Composite Analyzer; 28) Integrated Composite Analyzer with Damping Capabilities; 29) Computing Efficiency of Transfer of Microwave Power; 30) Program Calculates Power Demands of Electronic Designs; 31) Cost-Estimation Program; 32) Program Estimates Areas Required by Electronic Designs; 33) Program to Balance Mapped Turbopump Assemblies; 34) BiblioTech; 35) Controlling Mirror Tilt With a Bimorph Actuator; 36) Burst-Disk Device Simulates Effect of Pyrotechnic Device; 37) Bearing-Mounting Concept Accommodates Thermal Expansion; 38) Parallel-Plate Acoustic Absorbers for Hot Environments; 39) Adjustable-Length Strut Withstands Large Cyclic Loads; 40) Tool Indicates Contact Angles in Bearing Raceways; 41) Gravity Slides With Magnetic Braking; 42) High-Torque, Lightweight, Pneumatically Driven Wrench for Small Spaces; 43) Device for Testing Compatibility of an O-Ring; 44) Magnetic Heat Pump Containing Flow Diverters; 45) Variable-Tilt Helicopter Rotor Mast; 46) "Beach-Ball" Robotic Rovers; 47) Apparatus Would Measure Temperatures of Ball Bearings; 48) Flexible Borescope for Inspecting Ducts; 49) Texturing Copper To Reduce Secondary Emission of Electrons; 50) Automated Laser Cutting in Three Dimensions; 51) Algorithm Helps Monitor Engine Operation; 52) Flexible Revision of Data-Processing Communications; 53) Software for Managing the Use of Land; 54) Thermal Strap Increases Cryocooling Efficiency; 55) Reversible Nut With Engagement Indication; 56) Control Algorithms for Kinematically Redundant Manipulators; 57) Computed Hydrogen-Flow Splits in a Rocket Engine; 58) Pressure and Thermal Modeling of Rocket Launches; 59) Field of View of a Spacecraft Antenna: Analysis and Software; 60) Digital Controller for Laser-Beam-Steering Subsystem; 61) More About Beam-Steering Subsystem for Laser Communication; 62) Digital Controller for Laser-Beam-Steering Subsystem: Part 2; 63) Interface Circuit Board for Space-Shuttle Communications; 64) Automated Planning of Spacecraft Telecommunications; 65) Artifacts of Spectral Analysis of Instrument Readings; 66) Neural-Network Controller for Vibration Suppression; 67) Adaptive Finite-Element Computation in Fracture Mechanics; 68) Attitude Control for the Cassini Spacecraft; 69) Analytical Model for Fluid Dynamics in a Microgravity Environment; 70) Study of Rocket-Engine Joints Bonded by NVCU/NARloy-Z; 71) Improved Silicon Nitride for Advanced Heat Engines; 72) Parameters for Welding Aluminum/Lithium Alloys; 73) Lightweight Composite Intertank Structure; 74) Foil Patches Seal Small Vacuum Leaks; 75) Data Base on Cables and Connectors; 76) Effect of Clock Mode on Radiation Hardnessf an ADC; and 77) Fault-Tolerant Control for a Robotic Inspection System.

Use of Vacuum Bagging for Fabricating Thermoplastic Microfluidic Devices

PubMed Central

Cassano, Christopher L.; Simon, Andrew J.; Liu, Wei; Fredrickson, Carl; Fan, Z. Hugh

2014-01-01

In this work we present a novel thermal bonding method for thermoplastic microfluidic devices. This simple method employs a modified vacuum bagging technique, a concept borrowed from the aerospace industry, to produce conventional thick substrate microfluidic devices, as well as multi-layer film devices. The bonds produced using this method are superior to those obtained using conventional thermal bonding methods, including thermal lamination, and are capable of sustaining burst pressures in excess of 550 kPa. To illustrate the utility of this method, thick substrate devices were produced, as well as a six-layer film device that incorporated several complex features. PMID:25329244

Spontaneous quasi single helicity regimes in EXTRAP T2R reversed-field pinch

NASA Astrophysics Data System (ADS)

Frassinetti, L.; Brunsell, P. R.; Drake, J. R.; Menmuir, S.; Cecconello, M.

2007-11-01

In recent years, good progress toward a better understanding and control of the plasma performance in reversed-field pinch devices has been made. These improvements consist both of the discovery of spontaneous plasma regimes, termed the quasi single helicity (QSH) regime, in which part of the plasma core is no longer stochastic, and of the development of techniques for active control of plasma instabilities. In this paper, a systematic study of spontaneous QSH in the EXTRAP T2R device [P. R. Brunsell, H. Bergsaker, M. Cecconello et al., Plasma Phys. Control. Fusion 43, 1457 (2001)] is presented. In this device, QSH states can occur spontaneously and it is associated with magnetic and thermal structures. A statistical analysis to determine the most favorable experimental conditions to have a transition to the QSH regime will be presented. The results described here are useful to understand the underlying properties of QSH regimes in view of future applications of the QSH active control in EXTRAP T2R; they are also important to have a comparison with the QSH studied in other devices.

Exponential increase in the on-off ratio of conductance in organic memory devices by controlling the surface morphology of the devices

NASA Astrophysics Data System (ADS)

Vyas, Giriraj; Dagar, Parveen; Sahu, Satyajit

2018-05-01

We have shown an exponential increase in the ratio of conductance in the on and off states of switching devices by controlling the surface morphology of the thin films for the device by depositing at different rotational speeds. The pinholes which are preferred topography on the surface at higher rotational speed give rise to higher on-off ratio of current from the devices fabricated at the speed. The lower rotational speed contributes to higher thickness of the film and hence no switching. For thicker films, the domain is formed due to phase segregation between the two components in the film, which also indicates that the film is far from thermal equilibrium. At higher speed, there is very little scope of segregation when the film is drying up. Hence, there are only few pinholes on the surface of the film which are shallow. So, the filamentary mechanism of switching in memory devices can be firmly established by varying the speed of thin film deposition which leads to phase segregation of the materials. Thus, the formation of filament can be regulated by controlling the thickness and the surface morphology.

New Frontiers for Applications of Thermal Infrared Imaging Devices: Computational Psychopshysiology in the Neurosciences

PubMed Central

Cardone, Daniela; Merla, Arcangelo

2017-01-01

Thermal infrared imaging has been proposed, and is now used, as a tool for the non-contact and non-invasive computational assessment of human autonomic nervous activity and psychophysiological states. Thanks to a new generation of high sensitivity infrared thermal detectors and the development of computational models of the autonomic control of the facial cutaneous temperature, several autonomic variables can be computed through thermal infrared imaging, including localized blood perfusion rate, cardiac pulse rate, breath rate, sudomotor and stress responses. In fact, all of these parameters impact on the control of the cutaneous temperature. The physiological information obtained through this approach, could then be used to infer about a variety of psychophysiological or emotional states, as proved by the increasing number of psychophysiology or neurosciences studies that use thermal infrared imaging. This paper presents a review of the principal achievements of thermal infrared imaging in computational psychophysiology, focusing on the capability of the technique for providing ubiquitous and unwired monitoring of psychophysiological activity and affective states. It also presents a summary on the modern, up-to-date infrared sensors technology. PMID:28475155

New Frontiers for Applications of Thermal Infrared Imaging Devices: Computational Psychopshysiology in the Neurosciences.

PubMed

Cardone, Daniela; Merla, Arcangelo

2017-05-05

Thermal infrared imaging has been proposed, and is now used, as a tool for the non-contact and non-invasive computational assessment of human autonomic nervous activity and psychophysiological states. Thanks to a new generation of high sensitivity infrared thermal detectors and the development of computational models of the autonomic control of the facial cutaneous temperature, several autonomic variables can be computed through thermal infrared imaging, including localized blood perfusion rate, cardiac pulse rate, breath rate, sudomotor and stress responses. In fact, all of these parameters impact on the control of the cutaneous temperature. The physiological information obtained through this approach, could then be used to infer about a variety of psychophysiological or emotional states, as proved by the increasing number of psychophysiology or neurosciences studies that use thermal infrared imaging. This paper presents a review of the principal achievements of thermal infrared imaging in computational psychophysiology, focusing on the capability of the technique for providing ubiquitous and unwired monitoring of psychophysiological activity and affective states. It also presents a summary on the modern, up-to-date infrared sensors technology.

Electro-thermal control of aluminum-doped zinc oxide/vanadium dioxide multilayered thin films for smart-device applications

PubMed Central

Skuza, J. R.; Scott, D. W.; Mundle, R. M.; Pradhan, A. K.

2016-01-01

We demonstrate the electro-thermal control of aluminum-doped zinc oxide (Al:ZnO) /vanadium dioxide (VO2) multilayered thin films, where the application of a small electric field enables precise control of the applied heat to the VO2 thin film to induce its semiconductor-metal transition (SMT). The transparent conducting oxide nature of the top Al:ZnO film can be tuned to facilitate the fine control of the SMT of the VO2 thin film and its associated properties. In addition, the Al:ZnO film provides a capping layer to the VO2 thin film, which inhibits oxidation to a more energetically favorable and stable V2O5 phase. It also decreases the SMT of the VO2 thin film by approximately 5–10 °C because of an additional stress induced on the VO2 thin film and/or an alteration of the oxygen vacancy concentration in the VO2 thin film. These results have significant impacts on technological applications for both passive and active devices by exploiting this near-room-temperature SMT. PMID:26884225

High Speed and High Functional Inverter Power Supplies for Plasma Generation and Control, and their Performance

NASA Astrophysics Data System (ADS)

Uesugi, Yoshihiko; Razzak, Mohammad A.; Kondo, Kenji; Kikuchi, Yusuke; Takamura, Shuichi; Imai, Takahiro; Toyoda, Mitsuhiro

The Rapid development of high power and high speed semiconductor switching devices has led to their various applications in related plasma fields. Especially, a high speed inverter power supply can be used as an RF power source instead of conventional linear amplifiers and a power supply to control the magnetic field in a fusion plasma device. In this paper, RF thermal plasma production and plasma heating experiments are described emphasis placed on using a static induction transistor inverter at a frequency range between 200 kHz and 2.5 MHz as an RF power supply. Efficient thermal plasma production is achieved experimentally by using a flexible and easily operated high power semiconductor inverter power supply. Insulated gate bipolar transistor (IGBT) inverter power supplies driven by a high speed digital signal processor are applied as tokamak joule coil and vertical coil power supplies to control plasma current waveform and plasma equilibrium. Output characteristics, such as the arbitrary bipolar waveform generation of a pulse width modulation (PWM) inverter using digital signal processor (DSP) can be successfully applied to tokamak power supplies for flexible plasma current operation and fast position control of a small tokamak.

Microelectromechanical System (MEMS) Device Being Developed for Active Cooling and Temperature Control

NASA Technical Reports Server (NTRS)

Beach, Duane E.

2003-01-01

High-capacity cooling options remain limited for many small-scale applications such as microelectronic components, miniature sensors, and microsystems. A microelectromechanical system (MEMS) using a Stirling thermodynamic cycle to provide cooling or heating directly to a thermally loaded surface is being developed at the NASA Glenn Research Center to meet this need. The device can be used strictly in the cooling mode or can be switched between cooling and heating modes in milliseconds for precise temperature control. Fabrication and assembly employ techniques routinely used in the semiconductor processing industry. Benefits of the MEMS cooler include scalability to fractions of a millimeter, modularity for increased capacity and staging to low temperatures, simple interfaces, limited failure modes, and minimal induced vibration. The MEMS cooler has potential applications across a broad range of industries such as the biomedical, computer, automotive, and aerospace industries. The basic capabilities it provides can be categorized into four key areas: 1) Extended environmental temperature range in harsh environments; 2) Lower operating temperatures for electronics and other components; 3) Precision spatial and temporal thermal control for temperature-sensitive devices; and 4) The enabling of microsystem devices that require active cooling and/or temperature control. The rapidly expanding capabilities of semiconductor processing in general, and microsystems packaging in particular, present a new opportunity to extend Stirling-cycle cooling to the MEMS domain. The comparatively high capacity and efficiency possible with a MEMS Stirling cooler provides a level of active cooling that is impossible at the microscale with current state-of-the-art techniques. The MEMS cooler technology builds on decades of research at Glenn on Stirling-cycle machines, and capitalizes on Glenn s emerging microsystems capabilities.

Study of Fluid Cooling Loop System in Chinese Manned Spacecraft

NASA Astrophysics Data System (ADS)

Jiang, Jun; Xu, Jiwan; Fan, Hanlin; Huang, Jiarong

2002-01-01

change. To solve the questions, a fluid cooling loop system must be applied to Chinese manned spacecraft besides other conventional thermal control methods, such as thermal control coatings, multiplayer insulation blankets, heat pipes, electro-heating adjustment temperature devices, and so on. The paper will introduce the thermal design of inner and outer fluid loop including their constitution and fundamental, etc. The capability of heat transportation and the accuracy of control temperature for the fluid loop will be evaluated and analyzed. To insure the air temperature of sealed cabins within 21+/-4, the inlet liquid temperature of condensing heat exchanger needs to be controlled within 9+/-2. To insure this, the inlet liquid temperature of middle heat exchanger needs to be controlled within 8+/-1.8. The inlet temperature point is controlled by a subsidiary loop adjusting: when the computer receives feedbacks of the deviation and the variety rate of deviation from the controlled temperature point. It drives the temperature control valve to adjust the flow flux distribution between the main loop through radiator and the subsidiary loop which isn't through radiator to control the temperature of the mixed fluid within 8+/-1.8. The paper will also introduce thermal designs of key parts in the cooling loop, such as space radiators, heat exchangers and cooling plates. Thermal simulated tests on the ground and flight tests have been performed to verify correctness of thermal designs. rational and the loop system works order. It realizes the circulation of absorbing heat dissipation to the loop and transferring it to radiator then radiating it to space. (2) loop control system controls inlet temperature of middle heat exchanger within 8+/-1.8 under various thermal cases. Thermal design of the middle heat exchanger insures inlet temperature of condensing heat within 9+/-2. Thereby, the air temperature of sealed cabins is controlled within about 21+/-4 accurately. (3) The thermal designs of the key heat exchanging parts (such as radiator, heat exchangers and cooling plates) in the cooling loop are rational and effective, they meet the requirements of heat exchanging and assure the entire system work order.

Optoelectronic Fibers via Selective Amplification of In-Fiber Capillary Instabilities.

PubMed

Wei, Lei; Hou, Chong; Levy, Etgar; Lestoquoy, Guillaume; Gumennik, Alexander; Abouraddy, Ayman F; Joannopoulos, John D; Fink, Yoel

2017-01-01

Thermally drawn metal-insulator-semiconductor fibers provide a scalable path to functional fibers. Here, a ladder-like metal-semiconductor-metal photodetecting device is formed inside a single silica fiber in a controllable and scalable manner, achieving a high density of optoelectronic components over the entire fiber length and operating at a bandwidth of 470 kHz, orders of magnitude larger than any other drawn fiber device. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

An investigation of the SNS Josephson junction as a three-terminal device. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Meissner, H.; Prans, G. P.

1973-01-01

A particular phenomenon of the SNS Josephson junction was investigated; i.e., control by a current entering the normal region and leaving through one of the superconducting regions. The effect of the control current on the junction was found to be dependent upon the ration of the resistances of the two halves of the N layer. A low frequency, lumped, nonlinear model was proposed to describe the electrical characteristics of the device, and a method was developed to plot the dynamic junction resistance as a function of junction current. The effective thermal noise temperature of the sample was determined. Small signal linearized analysis of the device suggests its use as an impedance transformer, although geometric limitations must be overcome. Linear approximation indicates that it is reciprocal and no power gain is possible. It is felt that, with suitable metallurgical and geometrical improvements, the device has promise to become a superconducting transistor.

Laser device and method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Myers, J. D.

1985-06-25

A simplified, relatively inexpensive laser device, wherein the laser elements are fixed in a body exoskeleton of electrical insulating material having a low coefficient of thermal expansion. The preferred embodiment includes a shotgun type laser filter having parallel bores which receive the laser flashlamp and laser rod in fixed relation in a body chamber. The reflector surrounds the laser filter and retains the filter within the body chamber. In the preferred method of this invention, several controlled lasing pulses are generated with each illumination pulse of the flashlamp, substantially increasing the efficiency of the laser device. The number of pulsesmore » is generally controlled by increasing the voltage to the flashlamp. The rapid multiple lasing pulses generate an elongated plasma in a fluid medium, such as the vitreous fluid body of an eye which makes the laser device extemely efficient for treating glaucoma and other medical treatments.« less

Refurbishment and Automation of the Thermal/Vacuum Facilities at the Goddard Space Flight Center

NASA Technical Reports Server (NTRS)

Donohue, John T.; Johnson, Chris; Ogden, Rick; Sushon, Janet

1998-01-01

The thermal/vacuum facilities located at the Goddard Space Flight Center (GSFC) have supported both manned and unmanned space flight since the 1960s. Of the 11 facilities, currently 10 of the systems are scheduled for refurbishment and/or replacement as part of a 5-year implementation. Expected return on investment includes the reduction in test schedules, improvements in the safety of facility operations, reduction in the complexity of a test and the reduction in personnel support required for a test. Additionally, GSFC will become a global resource renowned for expertise in thermal engineering, mechanical engineering and for the automation of thermal/vacuum facilities and thermal/vacuum tests. Automation of the thermal/vacuum facilities includes the utilization of Programmable Logic Controllers (PLCs) and the use of Supervisory Control and Data Acquisition (SCADA) systems. These components allow the computer control and automation of mechanical components such as valves and pumps. In some cases, the chamber and chamber shroud require complete replacement while others require only mechanical component retrofit or replacement. The project of refurbishment and automation began in 1996 and has resulted in the computer control of one Facility (Facility #225) and the integration of electronically controlled devices and PLCs within several other facilities. Facility 225 has been successfully controlled by PLC and SCADA for over one year. Insignificant anomalies have occurred and were resolved with minimal impact to testing and operations. The amount of work remaining to be performed will occur over the next four to five years. Fiscal year 1998 includes the complete refurbishment of one facility, computer control of the thermal systems in two facilities, implementation of SCADA and PLC systems to support multiple facilities and the implementation of a Database server to allow efficient test management and data analysis.

Reliability of a novel thermal imaging system for temperature assessment of healthy feet.

PubMed

Petrova, N L; Whittam, A; MacDonald, A; Ainarkar, S; Donaldson, A N; Bevans, J; Allen, J; Plassmann, P; Kluwe, B; Ring, F; Rogers, L; Simpson, R; Machin, G; Edmonds, M E

2018-01-01

Thermal imaging is a useful modality for identifying preulcerative lesions ("hot spots") in diabetic foot patients. Despite its recognised potential, at present, there is no readily available instrument for routine podiatric assessment of patients at risk. To address this need, a novel thermal imaging system was recently developed. This paper reports the reliability of this device for temperature assessment of healthy feet. Plantar skin foot temperatures were measured with the novel thermal imaging device (Diabetic Foot Ulcer Prevention System (DFUPS), constructed by Photometrix Imaging Ltd) and also with a hand-held infrared spot thermometer (Thermofocus® 01500A3, Tecnimed, Italy) after 20 min of barefoot resting with legs supported and extended in 105 subjects (52 males and 53 females; age range 18 to 69 years) as part of a multicentre clinical trial. The temperature differences between the right and left foot at five regions of interest (ROIs), including 1st and 4th toes, 1st, 3rd and 5th metatarsal heads were calculated. The intra-instrument agreement (three repeated measures) and the inter-instrument agreement (hand-held thermometer and thermal imaging device) were quantified using intra-class correlation coefficients (ICCs) and the 95% confidence intervals (CI). Both devices showed almost perfect agreement in replication by instrument. The intra-instrument ICCs for the thermal imaging device at all five ROIs ranged from 0.95 to 0.97 and the intra-instrument ICCs for the hand-held-thermometer ranged from 0.94 to 0.97. There was substantial to perfect inter-instrument agreement between the hand-held thermometer and the thermal imaging device and the ICCs at all five ROIs ranged between 0.94 and 0.97. This study reports the performance of a novel thermal imaging device in the assessment of foot temperatures in healthy volunteers in comparison with a hand-held infrared thermometer. The newly developed thermal imaging device showed very good agreement in repeated temperature assessments at defined ROIs as well as substantial to perfect agreement in temperature assessment with the hand-held infrared thermometer. In addition to the reported non-inferior performance in temperature assessment, the thermal imaging device holds the potential to provide an instantaneous thermal image of all sites of the feet (plantar, dorsal, lateral and medial views). Diabetic Foot Ulcer Prevention System NCT02317835, registered December 10, 2014.

Nano-Localized Thermal Analysis and Mapping of Surface and Sub-Surface Thermal Properties Using Scanning Thermal Microscopy (SThM).

PubMed

Pereira, Maria J; Amaral, Joao S; Silva, Nuno J O; Amaral, Vitor S

2016-12-01

Determining and acting on thermo-physical properties at the nanoscale is essential for understanding/managing heat distribution in micro/nanostructured materials and miniaturized devices. Adequate thermal nano-characterization techniques are required to address thermal issues compromising device performance. Scanning thermal microscopy (SThM) is a probing and acting technique based on atomic force microscopy using a nano-probe designed to act as a thermometer and resistive heater, achieving high spatial resolution. Enabling direct observation and mapping of thermal properties such as thermal conductivity, SThM is becoming a powerful tool with a critical role in several fields, from material science to device thermal management. We present an overview of the different thermal probes, followed by the contribution of SThM in three currently significant research topics. First, in thermal conductivity contrast studies of graphene monolayers deposited on different substrates, SThM proves itself a reliable technique to clarify the intriguing thermal properties of graphene, which is considered an important contributor to improve the performance of downscaled devices and materials. Second, SThM's ability to perform sub-surface imaging is highlighted by thermal conductivity contrast analysis of polymeric composites. Finally, an approach to induce and study local structural transitions in ferromagnetic shape memory alloy Ni-Mn-Ga thin films using localized nano-thermal analysis is presented.

Electronic-carrier-controlled photochemical etching process in semiconductor device fabrication

DOEpatents

Ashby, C.I.H.; Myers, D.R.; Vook, F.L.

1988-06-16

An electronic-carrier-controlled photochemical etching process for carrying out patterning and selective removing of material in semiconductor device fabrication includes the steps of selective ion implanting, photochemical dry etching, and thermal annealing, in that order. In the selective ion implanting step, regions of the semiconductor material in a desired pattern are damaged and the remainder of the regions of the material not implanted are left undamaged. The rate of recombination of electrons and holes is increased in the damaged regions of the pattern compared to undamaged regions. In the photochemical dry etching step which follows ion implanting step, the material in the undamaged regions of the semiconductor are removed substantially faster than in the damaged regions representing the pattern, leaving the ion-implanted, damaged regions as raised surface structures on the semiconductor material. After completion of photochemical dry etching step, the thermal annealing step is used to restore the electrical conductivity of the damaged regions of the semiconductor material.

Electronic-carrier-controlled photochemical etching process in semiconductor device fabrication

DOEpatents

Ashby, Carol I. H.; Myers, David R.; Vook, Frederick L.

1989-01-01

An electronic-carrier-controlled photochemical etching process for carrying out patterning and selective removing of material in semiconductor device fabrication includes the steps of selective ion implanting, photochemical dry etching, and thermal annealing, in that order. In the selective ion implanting step, regions of the semiconductor material in a desired pattern are damaged and the remainder of the regions of the material not implanted are left undamaged. The rate of recombination of electrons and holes is increased in the damaged regions of the pattern compared to undamaged regions. In the photochemical dry etching step which follows ion implanting step, the material in the undamaged regions of the semiconductor are removed substantially faster than in the damaged regions representing the pattern, leaving the ion-implanted, damaged regions as raised surface structures on the semiconductor material. After completion of photochemical dry etching step, the thermal annealing step is used to restore the electrical conductivity of the damaged regions of the semiconductor material.

Dynamically Reconfigurable Metadevice Employing Nanostructured Phase-Change Materials

DOE PAGES

Zhu, Zhihua; Evans, Philip G.; Haglund, Richard F.; ...

2017-07-21

Mastering dynamic free-space spectral control and modulation in the near-infrared (NIR) and optical regimes remains a challenging task that is hindered by the available functional materials at high frequencies. In this work, we have realized an efficient metadevice capable of spectral control by minimizing the thermal mass of a vanadium dioxide phase-change material (PCM) and placing the PCM at the feed gap of a bow-tie field antenna. The device has an experimentally measured tuning range of up to 360 nm in the NIR and a modulation depth of 33% at the resonant wavelength. The metadevice is configured for integrated andmore » local heating, leading to faster switching and more precise spatial control compared with devices based on phase-change thin films. We envisage that the combined advantages of this device will open new opportunities for signal processing, memory, security, and holography at optical frequencies.« less

Dynamically Reconfigurable Metadevice Employing Nanostructured Phase-Change Materials.

PubMed

Zhu, Zhihua; Evans, Philip G; Haglund, Richard F; Valentine, Jason G

2017-08-09

Mastering dynamic free-space spectral control and modulation in the near-infrared (NIR) and optical regimes remains a challenging task that is hindered by the available functional materials at high frequencies. In this work, we have realized an efficient metadevice capable of spectral control by minimizing the thermal mass of a vanadium dioxide phase-change material (PCM) and placing the PCM at the feed gap of a bow-tie field antenna. The device has an experimentally measured tuning range of up to 360 nm in the NIR and a modulation depth of 33% at the resonant wavelength. The metadevice is configured for integrated and local heating, leading to faster switching and more precise spatial control compared with devices based on phase-change thin films. We envisage that the combined advantages of this device will open new opportunities for signal processing, memory, security, and holography at optical frequencies.

Control of exciton spin statistics through spin polarization in organic optoelectronic devices

PubMed Central

Wang, Jianpu; Chepelianskii, Alexei; Gao, Feng; Greenham, Neil C.

2012-01-01

Spintronics based on organic semiconductor materials is attractive because of its rich fundamental physics and potential for device applications. Manipulating spins is obviously important for spintronics, and is usually achieved by using magnetic electrodes. Here we show a new approach where spin populations can be controlled primarily by energetics rather than kinetics. We find that exciton spin statistics can be substantially controlled by spin-polarizing carriers after injection using high magnetic fields and low temperatures, where the Zeeman energy is comparable with the thermal energy. By using this method, we demonstrate that singlet exciton formation can be suppressed by up to 53% in organic light-emitting diodes, and the dark conductance of organic photovoltaic devices can be increased by up to 45% due to enhanced formation of triplet charge-transfer states, leading to less recombination to the ground state. PMID:23149736

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhu, Zhihua; Evans, Philip G.; Haglund, Richard F.

Mastering dynamic free-space spectral control and modulation in the near-infrared (NIR) and optical regimes remains a challenging task that is hindered by the available functional materials at high frequencies. In this work, we have realized an efficient metadevice capable of spectral control by minimizing the thermal mass of a vanadium dioxide phase-change material (PCM) and placing the PCM at the feed gap of a bow-tie field antenna. The device has an experimentally measured tuning range of up to 360 nm in the NIR and a modulation depth of 33% at the resonant wavelength. The metadevice is configured for integrated andmore » local heating, leading to faster switching and more precise spatial control compared with devices based on phase-change thin films. We envisage that the combined advantages of this device will open new opportunities for signal processing, memory, security, and holography at optical frequencies.« less

Room temperature triplet state spectroscopy of organic semiconductors.

PubMed

Reineke, Sebastian; Baldo, Marc A

2014-01-21

Organic light-emitting devices and solar cells are devices that create, manipulate, and convert excited states in organic semiconductors. It is crucial to characterize these excited states, or excitons, to optimize device performance in applications like displays and solar energy harvesting. This is complicated if the excited state is a triplet because the electronic transition is 'dark' with a vanishing oscillator strength. As a consequence, triplet state spectroscopy must usually be performed at cryogenic temperatures to reduce competition from non-radiative rates. Here, we control non-radiative rates by engineering a solid-state host matrix containing the target molecule, allowing the observation of phosphorescence at room temperature and alleviating constraints of cryogenic experiments. We test these techniques on a wide range of materials with functionalities spanning multi-exciton generation (singlet exciton fission), organic light emitting device host materials, and thermally activated delayed fluorescence type emitters. Control of non-radiative modes in the matrix surrounding a target molecule may also have broader applications in light-emitting and photovoltaic devices.

Controlling Hysteresis in Superconducting Weak Links and μ-Superconducting Quantum Interference Devices

NASA Astrophysics Data System (ADS)

Kumar, Nikhil; Winkelmann, C. B.; Biswas, Sourav; Courtois, H.; Gupta, Anjan K.

We have fabricated and studied the current-voltage characteristics of a number of niobium film based weak-link devices and μ-SQUIDs showing a critical current and two re-trapping currents. We have proposed a new understanding for the re-trapping currents in terms of thermal instabilities in different portions of the device. We also find that the superconducting proximity effect and the phase-slip processes play an important role in dictating the temperature dependence of the critical current in the non-hysteretic regime. The proximity effect helps in widening the temperature range of hysteresis-free characteristics. Finally we demonstrate control on temperature-range with hysteresis-free characteristics in two ways: 1) By using a parallel shunt resistor in close vicinity of the device, and 2) by reducing the weak-link width. Thus we get non-hysteretic behavior down to 1.3 K temperature in some of the studied devices. We acknowledge the financial support from CSIR, India as well as CNRS-Institute Neel, Grenoble, France.

System Level Analysis of a Water PCM HX Integrated into Orion's Thermal Control System

NASA Technical Reports Server (NTRS)

Navarro, Moses; Hansen, Scott; Seth, Rubik; Ungar, Eugene

2015-01-01

In a cyclical heat load environment such as low Lunar orbit, a spacecraft's radiators are not sized to reject the full heat load requirement. Traditionally, a supplemental heat rejection device (SHReD) such as an evaporator or sublimator is used to act as a "topper" to meet the additional heat rejection demands. Utilizing a Phase Change Material (PCM) heat exchanger (HX) as a SHReD provides an attractive alternative to evaporators and sublimators as PCM HXs do not use a consumable, thereby leading to reduced launch mass and volume requirements. In continued pursuit of water PCM HX development an Orion system level analysis was performed using Thermal Desktop for a water PCM HX integrated into Orion's thermal control system in a 100km Lunar orbit. The study verified of the thermal model by using a wax PCM and analyzed 1) placing the PCM on the Internal Thermal Control System (ITCS) versus the External Thermal Control System (ETCS) 2) use of 30/70 PGW verses 50/50 PGW and 3) increasing the radiator area in order to reduce PCM freeze times. The analysis showed that for the assumed operating and boundary conditions utilizing a water PCM HX on Orion is not a viable option for any case. Additionally, it was found that the radiator area would have to be increased by at least 40% in order to support a viable water-based PCM HX.

Thermally tunable VO2-SiO2 nanocomposite thin-film capacitors

NASA Astrophysics Data System (ADS)

Sun, Yifei; Narayanachari, K. V. L. V.; Wan, Chenghao; Sun, Xing; Wang, Haiyan; Cooley, Kayla A.; Mohney, Suzanne E.; White, Doug; Duwel, Amy; Kats, Mikhail A.; Ramanathan, Shriram

2018-03-01

We present a study of co-sputtered VO2-SiO2 nanocomposite dielectric thin-film media possessing continuous temperature tunability of the dielectric constant. The smooth thermal tunability is a result of the insulator-metal transition in the VO2 inclusions dispersed within an insulating matrix. We present a detailed comparison of the dielectric characteristics of this nanocomposite with those of a VO2 control layer and of VO2/SiO2 laminate multilayers of comparable overall thickness. We demonstrated a nanocomposite capacitor that has a thermal capacitance tunability of ˜60% between 25 °C and 100 °C at 1 MHz, with low leakage current. Such thermally tunable capacitors could find potential use in applications such as sensing, thermal cloaks, and phase-change energy storage devices.

Design and evaluation of a nondestructive fissile assay device for HTGR fuel samples

DOE Office of Scientific and Technical Information (OSTI.GOV)

McNeany, S. R.; Knoll, R. W.; Jenkins, J. D.

1979-02-01

Nondestructive assay of fissile material plays an important role in nuclear fuel processing facilities. Information for product quality control, plant criticality safety, and nuclear materials accountability can be obtained from assay devices. All of this is necessary for a safe, efficient, and orderly operation of a production plant. Presented here is a design description and an operational evaluation of a device developed to nondestructively assay small samples of High-Temperature Gas-Cooled Reactor (HTGR) fuel. The measurement technique employed consists in thermal-neutron irradiation of a sample followed by pneumatic transfer to a high-efficiency neutron detector where delayed neutrons are counted. In general,more » samples undergo several irradiation and count cycles during a measurement. The total number of delayed-neutron counts accumulated is translated into grams of fissile mass through comparison with the counts accumulated in an identical irradiation and count sequence of calibration standards. Successful operation of the device through many experiments over a one-year period indicates high operational reliability. Tests of assay precision show this to be better than 0.25% for measurements of 10 min. Assay biases may be encountered if calibration standards are not representative of unknown samples, but reasonable care in construction and control of standards should lead to no more than 0.2% bias in the measurements. Nondestructive fissile assay of HTGR fuel samples by thermal-neutron irradiation and delayed-neutron detection has been demonstrated to be a rapid and accurate analysis technique. However, careful attention and control must be given to calibration standards to see that they remain representative of unknown samples.« less

THERMALLY OPERATED VAPOR VALVE

DOEpatents

Dorward, J.G. Jr.

1959-02-10

A valve is presented for use in a calutron to supply and control the vapor to be ionized. The invention provides a means readily operable from the exterior of the vacuum tank of the apparatuss without mechanical transmission of forces for the quick and accurate control of the ionizing arc by a corresponding control of gas flow theretos thereby producing an effective way of carefully regulating the operation of the calutron. The invention consists essentially of a tube member extending into the charge bottle of a calutron devices having a poppet type valve closing the lower end of the tube. An electrical heating means is provided in the valve stem to thermally vary the length of the stem to regulate the valve opening to control the flow of material from the charge bottle.

Passive thermal management using phase change materials

NASA Astrophysics Data System (ADS)

Ganatra, Yash Yogesh

The trend of enhanced functionality and reducing thickness of mobile devices has. led to a rapid increase in power density and a potential thermal bottleneck since. thermal limits of components remain unchanged. Active cooling mechanisms are not. feasible due to size, weight and cost constraints. This work explores the feasibility. of a passive cooling system based on Phase Change Materials (PCMs) for thermal. management of mobile devices. PCMs stabilize temperatures due to the latent heat. of phase change thus increasing the operating time of the device before threshold. temperatures are exceeded. The primary contribution of this work is the identification. of key parameters which influence the design of a PCM based thermal management. system from both the experiments and the numerical models. This work first identifies strategies for integrating PCMs in an electronic device. A. detailed review of past research, including experimental techniques and computational. models, yields key material properties and metrics to evaluate the performance of. PCMs. Subsequently, a miniaturized version of a conventional thermal conductivity. measurement technique is developed to characterize thermal resistance of PCMs. Further, latent heat and transition temperatures are also characterized for a wide. range of PCMs. In-situ measurements with PCMs placed on the processor indicate that some. PCMs can extend the operating time of the device by as much as a factor of 2.48. relative to baseline tests (with no PCMs). This increase in operating time is investigated. by computational thermal models that explore various integration locations, both at the package and device level.

Design and analysis on thermal adaptive clamping device for PPMgLN crystal used in solid state laser

NASA Astrophysics Data System (ADS)

Yan, Conglin; Chen, Yongliang; Zhang, Wei

2015-02-01

The quality of clamping device for PPMgLN crystal has a vital influence on the optical property of solid-state laser. It has highly requirements of work stability and environmental adaptation ability, especially the thermal adaptation under high temperature differences. To achieve thermal adaptation, structural stiffness will be unavoidably weakened. How to keep both enough stiffness and thermal adaptation as far as possible is the key design point and also difficult point. In this paper, a kind of flexible thermal release unit which can work permanent under 130+/-10°C is studied. Thermal compensation principle and flexible thermal release theory are applied. Analysis results indicate that this device can effectively decreased the thermal stress of the crystal from 85MPa to 0.66MPa. The results of the vibration resistance test on the optical axis direction of the crystal indicate that the device can provide at least 5.62N to resistant 57.2g impact vibration and 18.5g impact vibration in the side direction, well satisfied the requirements of ability to resistant 6g impact vibration.

Mechanically Stretchable and Electrically Insulating Thermal Elastomer Composite by Liquid Alloy Droplet Embedment.

PubMed

Jeong, Seung Hee; Chen, Si; Huo, Jinxing; Gamstedt, Erik Kristofer; Liu, Johan; Zhang, Shi-Li; Zhang, Zhi-Bin; Hjort, Klas; Wu, Zhigang

2015-12-16

Stretchable electronics and soft robotics have shown unsurpassed features, inheriting remarkable functions from stretchable and soft materials. Electrically conductive and mechanically stretchable materials based on composites have been widely studied for stretchable electronics as electrical conductors using various combinations of materials. However, thermally tunable and stretchable materials, which have high potential in soft and stretchable thermal devices as interface or packaging materials, have not been sufficiently studied. Here, a mechanically stretchable and electrically insulating thermal elastomer composite is demonstrated, which can be easily processed for device fabrication. A liquid alloy is embedded as liquid droplet fillers in an elastomer matrix to achieve softness and stretchability. This new elastomer composite is expected useful to enhance thermal response or efficiency of soft and stretchable thermal devices or systems. The thermal elastomer composites demonstrate advantages such as thermal interface and packaging layers with thermal shrink films in transient and steady-state cases and a stretchable temperature sensor.

Thermal Pyrolytic Graphite Enhanced Components

NASA Technical Reports Server (NTRS)

Hardesty, Robert E. (Inventor)

2015-01-01

A thermally conductive composite material, a thermal transfer device made of the material, and a method for making the material are disclosed. Apertures or depressions are formed in aluminum or aluminum alloy. Plugs are formed of thermal pyrolytic graphite. An amount of silicon sufficient for liquid interface diffusion bonding is applied, for example by vapor deposition or use of aluminum silicon alloy foil. The plugs are inserted in the apertures or depressions. Bonding energy is applied, for example by applying pressure and heat using a hot isostatic press. The thermal pyrolytic graphite, aluminum or aluminum alloy and silicon form a eutectic alloy. As a result, the plugs are bonded into the apertures or depressions. The composite material can be machined to produce finished devices such as the thermal transfer device. Thermally conductive planes of the thermal pyrolytic graphite plugs may be aligned in parallel to present a thermal conduction path.

Mechanical Autonomous Stochastic Heat Engine

NASA Astrophysics Data System (ADS)

Serra-Garcia, Marc; Foehr, André; Molerón, Miguel; Lydon, Joseph; Chong, Christopher; Daraio, Chiara

2016-07-01

Stochastic heat engines are devices that generate work from random thermal motion using a small number of highly fluctuating degrees of freedom. Proposals for such devices have existed for more than a century and include the Maxwell demon and the Feynman ratchet. Only recently have they been demonstrated experimentally, using, e.g., thermal cycles implemented in optical traps. However, recent experimental demonstrations of classical stochastic heat engines are nonautonomous, since they require an external control system that prescribes a heating and cooling cycle and consume more energy than they produce. We present a heat engine consisting of three coupled mechanical resonators (two ribbons and a cantilever) subject to a stochastic drive. The engine uses geometric nonlinearities in the resonating ribbons to autonomously convert a random excitation into a low-entropy, nonpassive oscillation of the cantilever. The engine presents the anomalous heat transport property of negative thermal conductivity, consisting in the ability to passively transfer energy from a cold reservoir to a hot reservoir.

Mechanical Autonomous Stochastic Heat Engine.

PubMed

Serra-Garcia, Marc; Foehr, André; Molerón, Miguel; Lydon, Joseph; Chong, Christopher; Daraio, Chiara

2016-07-01

Stochastic heat engines are devices that generate work from random thermal motion using a small number of highly fluctuating degrees of freedom. Proposals for such devices have existed for more than a century and include the Maxwell demon and the Feynman ratchet. Only recently have they been demonstrated experimentally, using, e.g., thermal cycles implemented in optical traps. However, recent experimental demonstrations of classical stochastic heat engines are nonautonomous, since they require an external control system that prescribes a heating and cooling cycle and consume more energy than they produce. We present a heat engine consisting of three coupled mechanical resonators (two ribbons and a cantilever) subject to a stochastic drive. The engine uses geometric nonlinearities in the resonating ribbons to autonomously convert a random excitation into a low-entropy, nonpassive oscillation of the cantilever. The engine presents the anomalous heat transport property of negative thermal conductivity, consisting in the ability to passively transfer energy from a cold reservoir to a hot reservoir.

Optical device for thermal diffusivity determination in liquids by reflection of a thermal wave

NASA Astrophysics Data System (ADS)

Sánchez-Pérez, C.; De León-Hernández, A.; García-Cadena, C.

2017-08-01

In this work, we present a device for determination of the thermal diffusivity using the oblique reflection of a thermal wave within a solid slab that is in contact with the medium to be characterized. By using the reflection near a critical angle under the assumption that thermal waves obey Snell's law of refraction with the square root of the thermal diffusivities, the unknown thermal diffusivity is obtained by simple formulae. Experimentally, the sensor response is measured using the photothermal beam deflection technique within a slab that results in a compact device with no contact of the laser probing beam with the sample. We describe the theoretical basis and provide experimental results to validate the proposed method. We determine the thermal diffusivity of tridistilled water and glycerin solutions with an error of less than 0.5%.

Epitaxial CdSe-Au nanocrystal heterostructures by thermal annealing.

PubMed

Figuerola, Albert; van Huis, Marijn; Zanella, Marco; Genovese, Alessandro; Marras, Sergio; Falqui, Andrea; Zandbergen, Henny W; Cingolani, Roberto; Manna, Liberato

2010-08-11

The thermal evolution of a collection of heterogeneous CdSe-Au nanosystems (Au-decorated CdSe nanorods, networks, vertical assemblies) prepared by wet-chemical approaches was monitored in situ in the transmission electron microscope. In contrast to interfaces that are formed during kinetically controlled wet chemical synthesis, heating under vacuum conditions results in distinct and well-defined CdSe/Au interfaces, located at the CdSe polar surfaces. The high quality of these interfaces should make the heterostructures more suitable for use in nanoscale electronic devices.

Design and Modeling of a Liquid Lithium LiMIT Loop

NASA Astrophysics Data System (ADS)

Szott, Matthew; Christenson, Michael; Stemmley, Steven; Ahn, Chisung; Andruczyk, Daniel; Ruzic, David

2017-10-01

The use of flowing liquid lithium in plasma facing components has been shown to reduce erosion and thermal stress damage, prolong device lifetime, decrease edge recycling, reduce impurities, and increase plasma performance, all while providing a clean and self-healing surface. The Liquid Metal Infused Trench (LiMIT) system has proven the concept of controlled thermoelectric magnetohydrodynamic-driven lithium flow for use in fusion relevant conditions, through tests at UIUC, HT-7, and Magnum PSI. As the use of liquid lithium in fusion devices progresses, emphasis must now be placed on full systems integration of flowing liquid metal concepts. The LiMIT system will be upgraded to include a full liquid lithium loop, which will pump lithium into the fusion device, utilize TEMHD to drive lithium through the vessel, and remove lithium for filtration and degassing. Flow control concepts recently developed at UIUC - including wetting control, dryout control, and flow velocity control - will be tested in conjunction in order to demonstrate a robust system. Lithium loop system requirements, designs, and modeling work will be presented, along with plans for installation and testing on the HIDRA device at UIUC. This work is supported by DOE/ALPS DE-FG02-99ER54515.

Focused ultrasound thermal therapy system with ultrasound image guidance and temperature measurement feedback.

PubMed

Lin, Kao-Han; Young, Sun-Yi; Hsu, Ming-Chuan; Chan, Hsu; Chen, Yung-Yaw; Lin, Win-Li

2008-01-01

In this study, we developed a focused ultrasound (FUS) thermal therapy system with ultrasound image guidance and thermocouple temperature measurement feedback. Hydraulic position devices and computer-controlled servo motors were used to move the FUS transducer to the desired location with the measurement of actual movement by linear scale. The entire system integrated automatic position devices, FUS transducer, power amplifier, ultrasound image system, and thermocouple temperature measurement into a graphical user interface. For the treatment procedure, a thermocouple was implanted into a targeted treatment region in a tissue-mimicking phantom under ultrasound image guidance, and then the acoustic interference pattern formed by image ultrasound beam and low-power FUS beam was employed as image guidance to move the FUS transducer to have its focal zone coincident with the thermocouple tip. The thermocouple temperature rise was used to determine the sonication duration for a suitable thermal lesion as a high power was turned on and ultrasound image was used to capture the thermal lesion formation. For a multiple lesion formation, the FUS transducer was moved under the acoustic interference guidance to a new location and then it sonicated with the same power level and duration. This system was evaluated and the results showed that it could perform two-dimensional motion control to do a two-dimensional thermal therapy with a small localization error 0.5 mm. Through the user interface, the FUS transducer could be moved to heat the target region with the guidance of ultrasound image and acoustic interference pattern. The preliminary phantom experimental results demonstrated that the system could achieve the desired treatment plan satisfactorily.

Self-adaptive thermal management - the fundamentals and applications in Li-polymer batteries

NASA Astrophysics Data System (ADS)

Geng, Xiaobao

The thermal management systems for electronic devices and their power sources are facing increasing challenge to accommodate the ever-changing environmental and operational conditions. The conventional thermal management systems, with a predominant focus on cooling, are often not sufficient in those cases. In addition, to support miniaturization, complex systems and broader applications (e.g., space and military), the thermal management system often needs to be compatible with smaller device and their fabrication processes, dissipate heat efficiently for localized heat spot, and meet the requirement of light weight and low power consumption. In order to address such issues, a self-adaptive thermal switch array (TSA) is proposed based on microelectromechanical systems (MEMS) technology which has the capability automatically change its thermal conductance according to the environmental and operational conditions. This TSA was actuated by low melting alloy (LMA) with neither control unit nor parasitic energy consumption. The idea has been first demonstrated by a prototype device with the stabilization temperatures under various power inputs investigated both experimentally and theoretically. When the power input was changed from 3.8W to 5.8W, the stabilization temperature of the device was increased only by 2.5°C due to the stabilization effect of TSA. The experimental data were found in good agreement with their theoretical value. Based on the theoretical model, two types of TSA, namely high-on and low-off, were further developed to increase on-state thermal conductance and decrease off-state thermal conductance, respectively. Compared with the low-off TSA, the high-on TSA can more efficiently cool the devices and stabilize their temperature at a value closer to the melting point of LMA even under higher power inputs. On the other hand, the startup time and energy consumption were significantly reduced with the low-off TSA design due to the enhanced off-state thermal insulation, making them more suitable for cold start applications. A few key design factors have been identified to increase the on-state thermal conductance, reduce the off-state thermal conductance and enhance their ratio (switching ratio). The TSAs were then applied to a Li-polymer battery stack to demonstrate the self-adaptive thermal management capability. When cold-started from -10°C, the TSA-regulated battery stack reached 20°C in ~10min. The operational temperature was sustained with a moderate discharge current until depletion, while maintaining a fairly uniform temperate distribution within the battery stack. Compared with the open-cooling case, the performance of the Li-polymer battery was significantly improved by TSA-regulated thermal management. The capacity and output energy were increased by 16% and 23%, respectively. With the low-off TSA, the cold-start time has been shortened to ~ 7min, while the capacity and output energy of battery stack were increased by 18% and 27%, respectively, as compared to open-cooling case. The promising results have also paved the way for improving the performance of self-adaptive thermal management through the key design parameters.

Transurethral ultrasound applicators with dynamic multi-sector control for prostate thermal therapy: In vivo evaluation under MR guidance

PubMed Central

Kinsey, Adam M.; Diederich, Chris J.; Rieke, Viola; Nau, William H.; Pauly, Kim Butts; Bouley, Donna; Sommer, Graham

2008-01-01

The purpose of this study was to explore the feasibility and performance of a multi-sectored tubular array transurethral ultrasound applicator for prostate thermal therapy, with potential to provide dynamic angular and length control of heating under MR guidance without mechanical movement of the applicator. Test configurations were fabricated, incorporating a linear array of two multi-sectored tubular transducers (7.8–8.4 MHz, 3 mm OD, 6 mm length), with three 120° independent active sectors per tube. A flexible delivery catheter facilitated water cooling (100 ml min−1) within an expandable urethral balloon (35 mm long×10 mm diameter). An integrated positioning hub allows for rotating and translating the transducer assembly within the urethral balloon for final targeting prior to therapy delivery. Rotational beam plots indicate ∼90°−100° acoustic output patterns from each 120° transducer sector, negligible coupling between sectors, and acoustic efficiencies between 41% and 53%. Experiments were performed within in vivo canine prostate (n=3), with real-time MR temperature monitoring in either the axial or coronal planes to facilitate control of the heating profiles and provide thermal dosimetry for performance assessment. Gross inspection of serial sections of treated prostate, exposed to TTC (triphenyl tetrazolium chloride) tissue viability stain, allowed for direct assessment of the extent of thermal coagulation. These devices created large contiguous thermal lesions (defined by 52 °C maximum temperature, t43=240 min thermal dose contours, and TTC tissue sections) that extended radially from the applicator toward the border of the prostate (∼15 mm) during a short power application (∼8−16 W per active sector, 8–15 min), with ∼200° or 360° sector coagulation demonstrated depending upon the activation scheme. Analysis of transient temperature profiles indicated progression of lethal temperature and thermal dose contours initially centered on each sector that coalesced within ∼5 min to produce uniform and contiguous zones of thermal destruction between sectors, with smooth outer boundaries and continued radial propagation in time. The dimension of the coagulation zone along the applicator was well-defined by positioning and active array length. Although not as precise as rotating planar and curvilinear devices currently under development for MR-guided procedures, advantages of these multi-sectored transurethral applicators include a flexible delivery catheter and that mechanical manipulation of the device using rotational motors is not required during therapy. This multi-sectored tubular array transurethral ultrasound technology has demonstrated potential for relatively fast and reasonably conformal targeting of prostate volumes suitable for the minimally invasive treatment of BPH and cancer under MR guidance, with further development warranted. PMID:18561684

Quantum control and engineering of single spins in diamond

NASA Astrophysics Data System (ADS)

Toyli, David M.

The past two decades have seen intensive research efforts aimed at creating quantum technologies that leverage phenomena such as coherence and entanglement to achieve device functionalities surpassing those attainable with classical physics. While the range of applications for quantum devices is typically limited by their cryogenic operating temperatures, in recent years point defects in semiconductors have emerged as potential candidates for room temperature quantum technologies. In particular, the nitrogen vacancy (NV) center in diamond has gained prominence for the ability to measure and control its spin under ambient conditions and for its potential applications in magnetic sensing. Here we describe experiments that probe the thermal limits to the measurement and control of single NV centers to identify the origin of the system's unique temperature dependence and that define novel thermal sensing applications for single spins. We demonstrate the optical measurement and coherent control of the spin at temperatures exceeding 600 K and show that its addressability is eventually limited by thermal quenching of the optical spin readout. These measurements provide important information for the electronic structure responsible for the optical spin initialization and readout processes and, moreover, suggest that the coherence of the NV center's spin states could be harnessed for thermometry applications. To that end, we develop novel quantum control techniques that selectively probe thermally induced shifts in the spin resonance frequencies while minimizing the defect's interactions with nearby nuclear spins. We use these techniques to extend the NV center's spin coherence for thermometry by 45-fold to achieve thermal sensitivities approaching 10 mK Hz-1/2 . We show the versatility of these techniques by performing measurements in a range of magnetic environments and at temperatures as high as 500 K. Together with diamond's ideal thermal, mechanical, and chemical properties, these measurements suggest that NV center sensors could be employed in a diverse range of applications such as intracellular thermometry, microfuidic thermometry, and scanning thermal microscopy. Finally, while the development of NV center technologies is motivated by the desirable properties of isolated defects in bulk diamond, the realization of many of these technologies, such as those using the spin as a proximal sensor, require a means to control the placement of NV centers within the diamond lattice. We demonstrate a method to pattern defect formation on sub-100-nm length scales using ion implantation and electron beam lithography techniques. The ability to engineer large scale arrays of NV centers with this method holds promise for a variety of applications in quantum information science and nanoscale sensing.

Spectrally-engineered solar thermal photovoltaic devices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lenert, Andrej; Bierman, David; Chan, Walker

A solar thermal photovoltaic device, and method of forming same, includes a solar absorber and a spectrally selective emitter formed on either side of a thermally conductive substrate. The solar absorber is configured to absorb incident solar radiation. The solar absorber and the spectrally selective emitter are configured with an optimized emitter-to-absorber area ratio. The solar thermal photovoltaic device also includes a photovoltaic cell in thermal communication with the spectrally selective emitter. The spectrally selective emitter is configured to permit high emittance for energies above a bandgap of the photovoltaic cell and configured to permit low emittance for energies belowmore » the bandgap.« less

Controlling Oxygen Mobility in Ruddlesden–Popper Oxides

PubMed Central

Lee, Dongkyu; Lee, Ho Nyung

2017-01-01

Discovering new energy materials is a key step toward satisfying the needs for next-generation energy conversion and storage devices. Among the various types of oxides, Ruddlesden–Popper (RP) oxides (A2BO4) are promising candidates for electrochemical energy devices, such as solid oxide fuel cells, owing to their attractive physicochemical properties, including the anisotropic nature of oxygen migration and controllable stoichiometry from oxygen excess to oxygen deficiency. Thus, understanding and controlling the kinetics of oxygen transport are essential for designing optimized materials to use in electrochemical energy devices. In this review, we first discuss the basic mechanisms of oxygen migration in RP oxides depending on oxygen nonstoichiometry. We then focus on the effect of changes in the defect concentration, crystallographic orientation, and strain on the oxygen migration in RP oxides. We also briefly review their thermal and chemical stability. Finally, we conclude with a perspective on potential research directions for future investigation to facilitate controlling oxygen ion migration in RP oxides. PMID:28772732

Optimization of Strontium Titanate (SrTiO3) Thin Films Fabricated by Metal Organic Chemical Vapor Deposition (MOCVD) for Microwave-Tunable Devices

DTIC Science & Technology

2015-12-01

induced (non)stoichiometry on the structure, dielectric response, and thermal conductivity of SrTiO3 thin films. Chemistry of Materials. 2012;24:331...must be below a few percent. The external sources of loss, such as conductor interface losses and various losses that inevitably arise from device...epitaxy • Excellent control of film stoichiometry and thickness • Large area uniformity and potential for complex structure coating • Optimized

Materials investigation of thermal triggers used in pressure relief devices on transit buses.

DOT National Transportation Integrated Search

2003-07-01

This investigation pertains to the composition and general condition of the thermally activated trigger mechanism of Pressure Relief Devices [PRD's], safety devices used on compressed natural gas cylinders commonly used to store fuel on transit buses...

Effects of thermal loading and hydrostatic pressure on reflecting wavelengths of double-coated fiber Bragg grating with different coating-layer thickness

NASA Astrophysics Data System (ADS)

Seraji, Faramarz E.; Toutian, Golnoush

2017-10-01

Fiber Bragg grating (FBG) of different configurations used as sensing devices are vulnerable to environmental factors, such as static pressures and thermal loading, which cause their characteristic Bragg reflecting wavelengths to up/down-shift. In this paper, by considering double-coated FBG with different primary and secondary coating materials, the effects of thermal loading and hydrostatic pressure on FBG with different coating-layer thicknesses are analyzed to find design criteria for controlling the Bragg wavelength shift. The obtained results of the analysis may be employed as criteria to design pressure and temperature sensors when using double-coated FBGs.

Electronic and Thermal Effects in the Insulator-Metal Phase Transition in VO2 Nano-Gap Junctions

DTIC Science & Technology

2014-11-27

VO2 , air, or SiO2, the 2 -0.50 -0.25 0.00 0.25 0.50 0 2 4 6 V Gap V App V o lt ag e (V ) time (ms) t p V I→M V M→I 100 400 700 1000 0.0 2.5 5.0 7.5...Electronic and thermal effects in the insulator-metal phase transition in VO2 nano-gap junctions Arash Joushaghani,1 Junho Jeong,1 Suzanne Paradis,2...Canada (Dated: 27 November 2014) By controlling the thermal transport of VO2 nano-gap junctions using device geometry, contact material, and applied

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moreno, Gilbert; Bennion, Kevin

This project will develop thermal management strategies to enable efficient and high-temperature wide-bandgap (WBG)-based power electronic systems (e.g., emerging inverter and DC-DC converter designs). The use of WBG-based devices in automotive power electronics will improve efficiency and increase driving range in electric-drive vehicles; however, the implementation of this technology is limited, in part, due to thermal issues. This project will develop system-level thermal models to determine the thermal limitations of current automotive power modules under elevated device temperature conditions. Additionally, novel cooling concepts and material selection will be evaluated to enable high-temperature silicon and WBG devices in power electronics components.more » WBG devices (silicon carbide [SiC], gallium nitride [GaN]) promise to increase efficiency, but will be driven as hard as possible. This creates challenges for thermal management and reliability.« less

Silicon Processors Using Organically Reconfigurable Techniques (SPORT)

DTIC Science & Technology

2014-05-19

towards producing SWPC devices. ATR measurements on these thin films reveal a 30% increase in the EO activity of the OEOM films after thermal ...poling and recover about 50% the EO activity of thermally -poled films without poling. A simple proof-of-concept device architecture was fabricated and...device in peer-reviewed literature. New organic EO host materials developed at UD for the SPORT program offer increased thermal stability and EO

Thermal management in MoS2 based integrated device using near-field radiation

NASA Astrophysics Data System (ADS)

Peng, Jiebin; Zhang, Gang; Li, Baowen

2015-09-01

Recently, wafer-scale growth of monolayer MoS2 films with spatial homogeneity is realized on SiO2 substrate. Together with the latest reported high mobility, MoS2 based integrated electronic devices are expected to be fabricated in the near future. Owing to the low lattice thermal conductivity in monolayer MoS2, and the increased transistor density accompanied with the increased power density, heat dissipation will become a crucial issue for these integrated devices. In this letter, using the formalism of fluctuation electrodynamics, we explored the near-field radiative heat transfer from a monolayer MoS2 to graphene. We demonstrate that in resonance, the maximum heat transfer via near-field radiation between MoS2 and graphene can be ten times higher than the in-plane lattice thermal conduction for MoS2 sheet. Therefore, an efficient thermal management strategy for MoS2 integrated device is proposed: Graphene sheet is brought into close proximity, 10-20 nm from MoS2 device; heat energy transfer from MoS2 to graphene via near-field radiation; this amount of heat energy then be conducted to contact due to ultra-high lattice thermal conductivity of graphene. Our work sheds light for developing cooling strategy for nano devices constructing with low thermal conductivity materials.

An Investigation Into: I) Active Flow Control for Cold-Start Performance Enhancement of a Pump-Assisted, Capillary-Driven, Two-Phase Cooling Loop II) Surface Tension of n-Pentanol + Water, a Self-Rewetting Working Fluid, From 25 °C to 85 °C

NASA Astrophysics Data System (ADS)

Bejarano, Roberto Villa

Cold-start performance enhancement of a pump-assisted, capillary-driven, two-phase cooling loop was attained using proportional integral and fuzzy logic controls to manage the boiling condition inside the evaporator. The surface tension of aqueous solutions of n-Pentanol, a self-rewetting fluid, was also investigated for enhancing heat transfer performance of capillary driven (passive) thermal devices was also studied. A proportional-integral control algorithm was used to regulate the boiling condition (from pool boiling to thin-film boiling) and backpressure in the evaporator during cold-start and low heat input conditions. Active flow control improved the thermal resistance at low heat inputs by 50% compared to the baseline (constant flow rate) case, while realizing a total pumping power savings of 56%. Temperature overshoot at start-up was mitigated combining fuzzy-logic with a proportional-integral controller. A constant evaporator surface temperature of 60°C with a variation of +/-8°C during start-up was attained with evaporator thermal resistances as low as 0.10 cm2--K/W. The surface tension of aqueous solutions of n-Pentanol, a self-rewetting working fluid, as a function of concentration and temperature were also investigated. Self-rewetting working fluids are promising in two-phase heat transfer applications because they have the ability to passively drive additional working fluid towards the heated surface; thereby increasing the dryout limitations of the thermal device. Very little data is available in literature regarding the surface tension of these fluids due to the complexity involved in fluid handling, heating, and experimentation. Careful experiments were performed to investigate the surface tension of n-Pentanol + water. The concentration and temperature range investigated were from 0.25%wt. to1.8%wt and 25°C to 85°C, respectively.

Microbubble-assisted optofluidic control using a photothermal waveguide

NASA Astrophysics Data System (ADS)

Cheng, YuPeng; Yang, JianXin; Li, ZongBao; Zhu, DeBin; Cai, Xiang; Hu, Xiaowen; Huang, Wen; Xing, XiaoBo

2017-10-01

A convenient and easily controllable microfluidic system was proposed based on a photothermal device. Here, graphene oxide was assembled on an optical waveguide, which could serve as a miniature heat source to generate a microbubble and to control dynamic behaviors of flow by adjusting optical power at the micrometer scale. Micro/nanoparticles were used to demonstrate the trace of fluid flow around the microbubble, which displayed the ability of the flow to capture, transmit, and rotate particles in thermal convection. Correspondingly, three-dimensional theoretical simulation combining thermodynamics with hydrodynamics analyzed the distribution of the velocity field induced by the microbubble for collection and driving of particles. Furthermore, the photothermal waveguide would be developed into a microbubble-based device in the manipulation or transmission of micro/nanoparticles.

Electrothermally actuated tip-tilt-piston micromirror with integrated varifocal capability.

PubMed

Morrison, Jessica; Imboden, Matthias; Little, Thomas D C; Bishop, D J

2015-04-06

MEMS micromirrors have proven to be very important optical devices with applications ranging from steerable mirrors for switches and cross-connects to spatial light modulators for correcting optical distortions. Usually beam steering and focusing are done with different MEMS devices and tilt angles in excess of 10 degrees are seldom obtained. Here we describe a single MEMS device that combines tip/tilt, piston mode and varifocal capability into a single, low cost device with very large tilt angles. Our device consists of a 400 micron diameter mirror driven with thermal bimorphs. We have demonstrated deflection angles of ± 40 degrees along both axes, a tunable focal length which varies between -0.48 mm to + 20.5 mm and a piston mode range of 300 microns - four separately controllable degrees of freedom in a single device. Potential applications range from smart lighting to optical switches and devices for telecom systems.

Comparison of Thermal Manikin Modeling and Human Subjects' Response During Use of Cooling Devices Under Personal Protective Ensembles in the Heat.

PubMed

Quinn, Tyler; Kim, Jung-Hyun; Seo, Yongsuk; Coca, Aitor

2018-06-01

IntroductionPersonal protective equipment (PPE) recommended for use in West Africa during the Ebola outbreak increased risk for heat illness, and countermeasures addressing this issue would be valuable.Hypothesis/ProblemThe purpose of this study was to examine the physiological impact and heat perception of four different personal cooling devices (PCDs) under impermeable PPE during low-intensity exercise in a hot and humid environment using thermal manikin modeling and human testing. Six healthy male subjects walked on a treadmill in a hot/humid environment (32°C/92% relative humidity [RH]) at three metabolic equivalents (METs) for 60 minutes wearing PPE recommended for use in West Africa and one of four different personal cooling devices (PCDs; PCD1, PCD2, PCD3, and PCD4) or no PCD for control (CON). The same ensembles were tested with thermal manikin modeling software in the same conditions to compare the results. All PCDs seemed to reduce physiological heat stress characteristics when worn under PPE compared to CON. Both the manikin and human testing provided similar results in core temperature (Tc) and heat sensation (HS) in both magnitude and relationship. While the manikin and human data provided similar skin temperature (Tsk) characterization, Tsk estimation by the manikin seemed to be slightly over-estimated. Weight loss, as estimated by the manikin, was under-estimated compared to the human measurement. Personal cooling device use in conjunction with impermeable PPE may be advantageous in mitigating physiological and perceptual burdens of heat stress. Evaluation of PCDs worn under PPE can be done effectively via human or manikin testing; however, Tsk may be over-estimated and weight loss may be under-estimated. Thermal manikin testing of PCDs may provide fast and accurate information to persons recommending or using PCDs with PPE. QuinnT, KimJH, SeoY, CocaA. Comparison of thermal manikin modeling and human subjects' response during use of cooling devices under personal protective ensembles in the heat. Prehosp Disaster Med. 2018;33(3):279-287.

Development of an artificial multifunctional foot: A project review

NASA Astrophysics Data System (ADS)

Almeida, João; Ferreira, Maria José; Lobarinhas, Pedro; Silva, Luís F.; Leite, Abílio; Araújo, Alfredo; Sousa, Fernando

2013-10-01

The main purpose of this project is the development of a multifunctional artificial foot, capable of duplicate a human foot in a laboratory environment, in order to evaluate and simulate footwear's performance under certain conditions. This foot is used as a laboratory prototype and is multisegmented, in order that each section is controlled independently in terms of heat generation and sweating rate, therefore it is possible to simulate more accurately the real behaviour of a human foot. The device produces thermal insulation values that will help to design footwear with better ability in terms of thermal comfort, replacing human volunteers in thermal comfort perception tests, which are very subjective. The prototype was already tested, and preliminary results indicated that thermal insulation values are within the range of expected values produced by other foot thermal manikins and by human volunteers' tests. This fact suggests that this lab prototype can be used infuture thermal comfort evaluations.

Aerogels for Thermal Insulation of Thermoelectric Devices

NASA Technical Reports Server (NTRS)

Sakamoto, Jeffrey; Fleurial, Jean-Pierre; Snyder, Jeffrey; Jones, Steven; Caillat, Thierry

2006-01-01

Silica aerogels have been shown to be attractive for use as thermal-insulation materials for thermoelectric devices. It is desirable to thermally insulate the legs of thermoelectric devices to suppress lateral heat leaks that degrade thermal efficiency. Aerogels offer not only high thermal- insulation effectiveness, but also a combination of other properties that are especially advantageous in thermoelectric- device applications. Aerogels are synthesized by means of sol-gel chemistry, which is ideal for casting insulation into place. As the scale of the devices to be insulated decreases, the castability from liquid solutions becomes increasingly advantageous: By virtue of castability, aerogel insulation can be made to encapsulate devices having any size from macroscopic down to nanoscopic and possibly having complex, three-dimensional shapes. Castable aerogels can permeate voids having characteristic dimensions as small as nanometers. Hence, practically all the void space surrounding the legs of thermoelectric devices could be filled with aerogel insulation, making the insulation highly effective. Because aerogels have the lowest densities of any known solid materials, they would add very little mass to the encapsulated devices. The thermal-conductivity values of aerogels are among the lowest reported for any material, even after taking account of the contributions of convection and radiation (in addition to true thermal conduction) to overall effective thermal conductivities. Even in ambient air, the contribution of convection to effective overall thermal conductivity of an aerogel is extremely low because of the highly tortuous nature of the flow paths through the porous aerogel structure. For applications that involve operating temperatures high enough to give rise to significant amounts of infrared radiation, opacifiers could be added to aerogels to reduce the radiative contributions to overall effective thermal conductivities. One example of an opacifier is carbon black, which absorbs infrared radiation. Another example of an opacifier is micron- sized metal flakes, which reflect infrared radiation. Encapsulation in cast aerogel insulation also can help prolong the operational lifetimes of thermoelectric devices that must operate in vacuum and that contain SiGe or such advanced skutterudite thermoelectric materials as CoSb3 and CeFe3.5Co0.5Sb12. The primary cause of deterioration of most thermoelectric materials is thermal decomposition or sublimation (e.g., sublimation of Sb from CoSb3) at typical high operating temperatures. Aerogel present near the surface of CoSb3 can impede the outward transport of Sb vapor by establishing a highly localized, equilibrium Sb vapor atmosphere at the surface of the CoSb3.

Thermal Analysis of a Disposable, Instrument-Free DNA Amplification Lab-on-a-Chip Platform.

PubMed

Pardy, Tamás; Rang, Toomas; Tulp, Indrek

2018-06-04

Novel second-generation rapid diagnostics based on nucleic acid amplification tests (NAAT) offer performance metrics on par with clinical laboratories in detecting infectious diseases at the point of care. The diagnostic assay is typically performed within a Lab-on-a-Chip (LoC) component with integrated temperature regulation. However, constraints on device dimensions, cost and power supply inherent with the device format apply to temperature regulation as well. Thermal analysis on simplified thermal models for the device can help overcome these barriers by speeding up thermal optimization. In this work, we perform experimental thermal analysis on the simplified thermal model for our instrument-free, single-use LoC NAAT platform. The system is evaluated further by finite element modelling. Steady-state as well as transient thermal analysis are performed to evaluate the performance of a self-regulating polymer resin heating element in the proposed device geometry. Reaction volumes in the target temperature range of the amplification reaction are estimated in the simulated model to assess compliance with assay requirements. Using the proposed methodology, we demonstrated our NAAT device concept capable of performing loop-mediated isothermal amplification in the 20⁻25 °C ambient temperature range with 32 min total assay time.

Self-heating and scaling of thin body transistors

NASA Astrophysics Data System (ADS)

Pop, Eric

The most often cited technological roadblock of nanoscale electronics is the "power problem," i.e. power densities and device temperatures reaching levels that will prevent their reliable operation. Technology roadmap (ITRS) requirements are expected to lead to more heat dissipation problems, especially with the transition towards geometrically confined device geometries (SOI, FinFET, nanowires), and new materials with poor thermal properties. This work examines the physics of heat generation in silicon, and in the context of nanoscale CMOS transistors. A new Monte Carlo code (MONET) is introduced which uses analytic descriptions of both the electron bands and the phonon dispersion. Detailed heat generation statistics are computed in bulk and strained silicon, and within simple device geometries. It is shown that non-stationary transport affects heat generation near strongly peaked electric fields, and that self-heating occurs almost entirely in the drain end of short, quasi-ballistic devices. The dissipated power is spectrally distributed between the (slow) optical and (fast) acoustic phonon modes approximately by a ratio of two to one. In addition, this work explores the limits of device design and scaling from an electrical and thermal point of view. A self-consistent electro-thermal compact model for thin-body (SOI, GOI) devices is introduced for calculating operating temperature, saturation current and intrinsic gate delay. Self-heating is sensitive to several device parameters, such as raised source/drain height and material boundary thermal resistance. An experimental method is developed for extracting via/contact thermal resistance from electrical measurements. The analysis suggests it is possible to optimize device geometry in order to simultaneously minimize operating temperature and intrinsic gate delay. Electro-thermal contact and device design are expected to become more important with continued scaling.

Solar energy thermalization and storage device

DOEpatents

McClelland, John F.

1981-09-01

A passive solar thermalization and thermal energy storage assembly which is visually transparent. The assembly consists of two substantial parallel, transparent wall members mounted in a rectangular support frame to form a liquid-tight chamber. A semitransparent thermalization plate is located in the chamber, substantially paralled to and about equidistant from the transparent wall members to thermalize solar radiation which is stored in a transparent thermal energy storage liquid which fills the chamber. A number of the devices, as modules, can be stacked together to construct a visually transparent, thermal storage wall for passive solar-heated buildings.

Dielectric Coating Thermal Stabilization During GaAs-Based Laser Fabrication for Improved Device Yield

DTIC Science & Technology

2015-11-25

1 Dielectric coating thermal stabilization during GaAs-based laser fabrication for improved device yield 1 Michael K. Connors a, c), Jamal...side contact metal, underlying SiO2 dielectric coating, and semiconductor surface. A thermal-anneal procedure developed for the fabrication of GaAs...slab coupled optical waveguide (SCOW) ridge waveguide devices stabilizes the SiO2 dielectric coating, by means of outgassing and stress reduction

Design and Development of a Nearable Wireless System to Control Indoor Air Quality and Indoor Lighting Quality.

PubMed

Salamone, Francesco; Belussi, Lorenzo; Danza, Ludovico; Galanos, Theodore; Ghellere, Matteo; Meroni, Italo

2017-05-04

The article describes the results of the project "open source smart lamp" aimed at designing and developing a smart object able to manage and control the indoor environmental quality (IEQ) of the built environment. A first version of this smart object, built following a do-it-yourself (DIY) approach using a microcontroller, an integrated temperature and relative humidity sensor, and techniques of additive manufacturing, allows the adjustment of the indoor thermal comfort quality (ICQ), by interacting directly with the air conditioner. As is well known, the IEQ is a holistic concept including indoor air quality (IAQ), indoor lighting quality (ILQ) and acoustic comfort, besides thermal comfort. The upgrade of the smart lamp bridges the gap of the first version of the device providing the possibility of interaction with the air exchange unit and lighting system in order to get an overview of the potential of a nearable device in the management of the IEQ. The upgraded version was tested in a real office equipped with mechanical ventilation and an air conditioning system. This office was occupied by four workers. The experiment is compared with a baseline scenario and the results show how the application of the nearable device effectively optimizes both IAQ and ILQ.

Design and Development of a Nearable Wireless System to Control Indoor Air Quality and Indoor Lighting Quality

PubMed Central

Salamone, Francesco; Belussi, Lorenzo; Danza, Ludovico; Galanos, Theodore; Ghellere, Matteo; Meroni, Italo

2017-01-01

The article describes the results of the project “open source smart lamp” aimed at designing and developing a smart object able to manage and control the indoor environmental quality (IEQ) of the built environment. A first version of this smart object, built following a do-it-yourself (DIY) approach using a microcontroller, an integrated temperature and relative humidity sensor, and techniques of additive manufacturing, allows the adjustment of the indoor thermal comfort quality (ICQ), by interacting directly with the air conditioner. As is well known, the IEQ is a holistic concept including indoor air quality (IAQ), indoor lighting quality (ILQ) and acoustic comfort, besides thermal comfort. The upgrade of the smart lamp bridges the gap of the first version of the device providing the possibility of interaction with the air exchange unit and lighting system in order to get an overview of the potential of a nearable device in the management of the IEQ. The upgraded version was tested in a real office equipped with mechanical ventilation and an air conditioning system. This office was occupied by four workers. The experiment is compared with a baseline scenario and the results show how the application of the nearable device effectively optimizes both IAQ and ILQ. PMID:28471398

Fast-spectrum space-power-reactor concepts using boron control devices

NASA Technical Reports Server (NTRS)

Mayo, W.

1973-01-01

Several fast-spectrum space power reactor concepts that use boron carbide control devices were examined to determine the neutronic feasibility of the designs. The designs considered were (1) a 199-fuel-pin, 12-poison-reflector-control-drum reactor; (2) a 232-fuel-pin reactor with 12 reflector drums and three in-core control rods; (3) a 337-fuel-pin design with 12 incore control rods; and a 181-fuel-pin design with six drums closely coupled to the core to increase reactivity per drum. Adequate reactivity control and excess reactivity could be obtained for each concept, and the goals of 50,000 hours at 2.17 thermal megawatts with a lithium-7 coolant outlet temperature of 1222 K could be met without exceeding the 1-percent-clad-creep criterion. Heating rates in the boron carbide were calculated, but a heat transfer analysis was not done.

Thermal Transport in Diamond Films for Electronics Thermal Management

DTIC Science & Technology

2018-03-01

AFRL-RY-WP-TR-2017-0219 THERMAL TRANSPORT IN DIAMOND FILMS FOR ELECTRONICS THERMAL MANAGEMENT Samuel Graham Georgia Institute of Technology MARCH...general public, including foreign nationals. Copies may be obtained from the Defense Technical Information Center (DTIC) (http://www.dtic.mil...Signature// JOHN D. BLEVINS, Program Manager ROSS W. DETTMER, Chief Devices for Sensing Branch Devices for Sensing Branch Aerospace Components

Bifunctional metamaterials with simultaneous and independent manipulation of thermal and electric fields.

PubMed

Lan, Chuwen; Bi, Ke; Fu, Xiaojian; Li, Bo; Zhou, Ji

2016-10-03

Metamaterials offer a powerful way to manipulate a variety of physical fields ranging from wave fields (electromagnetic field, acoustic field, elastic wave, etc.), static fields (static magnetic field, static electric field) to diffusive fields (thermal field, diffusive mass). However, the relevant reports and studies are usually limited to a single physical field or functionality. In this study, we proposed and experimentally demonstrated a bifunctional metamaterial which could manipulate thermal and electric fields simultaneously and independently. Specifically, a composite with independently controllable thermal and electric conductivity was introduced, on the basis of which a bifunctional device capable of shielding thermal flux and concentrating electric current simultaneously was designed, fabricated and characterized. This work provides an encouraging example of metamaterials transcending their natural limitations, which offers a promising future in building a broad platform for the manipulation of multi-physics fields.

Could the heat sink effect of blood flow inside large vessels protect the vessel wall from thermal damage during RF-assisted surgical resection?

PubMed

González-Suárez, Ana; Trujillo, Macarena; Burdío, Fernando; Andaluz, Anna; Berjano, Enrique

2014-08-01

To assess by means of computer simulations whether the heat sink effect inside a large vessel (portal vein) could protect the vessel wall from thermal damage close to an internally cooled electrode during radiofrequency (RF)-assisted resection. First,in vivo experiments were conducted to validate the computational model by comparing the experimental and computational thermal lesion shapes created around the vessels. Computer simulations were then carried out to study the effect of different factors such as device-tissue contact, vessel position, and vessel-device distance on temperature distributions and thermal lesion shapes near a large vessel, specifically the portal vein. The geometries of thermal lesions around the vessels in the in vivo experiments were in agreement with the computer results. The thermal lesion shape created around the portal vein was significantly modified by the heat sink effect in all the cases considered. Thermal damage to the portal vein wall was inversely related to the vessel-device distance. It was also more pronounced when the device-tissue contact surface was reduced or when the vessel was parallel to the device or perpendicular to its distal end (blade zone), the vessel wall being damaged at distances less than 4.25 mm. The computational findings suggest that the heat sink effect could protect the portal vein wall for distances equal to or greater than 5 mm, regardless of its position and distance with respect to the RF-based device.

FIELD DEMONSTRATION AND QUALITY ASSURANCE ...

EPA Pesticide Factsheets

The Demonstration of innovative field devices for the measurement of mercury in soil and sediment is being conducted under the EPA's SITE Program in February 2003 at the United States Department of Energy's (DOE) Oak Ridge National Laboratory (ORNL) in Oak Ridge, Tennessee and the Tennessee Department of Environment and Conservation's Department of Energy Oversight facility in Oak Ridge, Tennessee. The primary purpose of the Demonstration is to evaluate innovative field devices for the measurement of mercury in soil and sediment based on their performance and cost as compared to a conventional, off-site laboratory analytical method. The five field measurement devices listed below will be demonstrated: .Metorex's X-M ET 2000 Metal Master Analyzer, X-Ray Fluorescence Analyzer .Milestone Inc.'s Direct Mercury Analyzer (DMA-80), Thermal Decomposition Instrument.NITON's XL-700 Series Multi-Element Analyzer, X-Ray Fluorescence Analyzer .Ohio Lumex's RA-915+ Portable Mercury Analyzer, Atomic Absorption Spectrometer, Thermal Decompostion Attachment RP 91C .MTI, Inc.'s PDV 5000 Hand Held Instrument, Anodic Stripping Voltamm eter<1). This Demonstration Plan describes the procedures that will be used to verify the performance and cost of each field measurement device. The plan incorporates the quality assurance and quality control elements needed to generate data of sufficient quality to document each device's performance and cost. A separate Innovative Technology Verifica

An integrated approach to develop, validate and operate thermo-physiological human simulator for the development of protective clothing.

PubMed

Psikuta, Agnes; Koelblen, Barbara; Mert, Emel; Fontana, Piero; Annaheim, Simon

2017-12-07

Following the growing interest in the further development of manikins to simulate human thermal behaviour more adequately, thermo-physiological human simulators have been developed by coupling a thermal sweating manikin with a thermo-physiology model. Despite their availability and obvious advantages, the number of studies involving these devices is only marginal, which plausibly results from the high complexity of the development and evaluation process and need of multi-disciplinary expertise. The aim of this paper is to present an integrated approach to develop, validate and operate such devices including technical challenges and limitations of thermo-physiological human simulators, their application and measurement protocol, strategy for setting test scenarios, and the comparison to standard methods and human studies including details which have not been published so far. A physical manikin controlled by a human thermoregulation model overcame the limitations of mathematical clothing models and provided a complementary method to investigate thermal interactions between the human body, protective clothing, and its environment. The opportunities of these devices include not only realistic assessment of protective clothing assemblies and equipment but also potential application in many research fields ranging from biometeorology, automotive industry, environmental engineering, and urban climate to clinical and safety applications.

An integrated approach to develop, validate and operate thermo-physiological human simulator for the development of protective clothing

PubMed Central

PSIKUTA, Agnes; KOELBLEN, Barbara; MERT, Emel; FONTANA, Piero; ANNAHEIM, Simon

2017-01-01

Following the growing interest in the further development of manikins to simulate human thermal behaviour more adequately, thermo-physiological human simulators have been developed by coupling a thermal sweating manikin with a thermo-physiology model. Despite their availability and obvious advantages, the number of studies involving these devices is only marginal, which plausibly results from the high complexity of the development and evaluation process and need of multi-disciplinary expertise. The aim of this paper is to present an integrated approach to develop, validate and operate such devices including technical challenges and limitations of thermo-physiological human simulators, their application and measurement protocol, strategy for setting test scenarios, and the comparison to standard methods and human studies including details which have not been published so far. A physical manikin controlled by a human thermoregulation model overcame the limitations of mathematical clothing models and provided a complementary method to investigate thermal interactions between the human body, protective clothing, and its environment. The opportunities of these devices include not only realistic assessment of protective clothing assemblies and equipment but also potential application in many research fields ranging from biometeorology, automotive industry, environmental engineering, and urban climate to clinical and safety applications. PMID:28966294

Wide memory window in graphene oxide charge storage nodes

NASA Astrophysics Data System (ADS)

Wang, Shuai; Pu, Jing; Chan, Daniel S. H.; Cho, Byung Jin; Loh, Kian Ping

2010-04-01

Solution-processable, isolated graphene oxide (GO) monolayers have been used as a charge trapping dielectric in TaN gate/Al2O3/isolated GO sheets/SiO2/p-Si memory device (TANOS). The TANOS type structure serves as memory device with the threshold voltage controlled by the amount of charge trapped in the GO sheet. Capacitance-Voltage hysteresis curves reveal a 7.5 V memory window using the sweep voltage of -5-14 V. Thermal reduction in the GO to graphene reduces the memory window to 1.4 V. The unique charge trapping properties of GO points to the potential applications in flexible organic memory devices.

A modified SILCS contraceptive diaphragm for long-term controlled release of the HIV microbicide dapivirine.

PubMed

Major, Ian; Boyd, Peter; Kilbourne-Brook, Maggie; Saxon, Gene; Cohen, Jessica; Malcolm, R Karl

2013-07-01

There is considerable interest in developing new multipurpose prevention technologies to address women's reproductive health needs. This study describes an innovative barrier contraceptive device--based on the SILCS diaphragm--that also provides long-term controlled release of the lead candidate anti-HIV microbicide dapivirine. Diaphragm devices comprising various dapivirine-loaded polymer spring cores overmolded with a nonmedicated silicone elastomer sheath were fabricated by injection molding processes. In vitro release testing, thermal analysis and mechanical characterization were performed on the devices. A diaphragm device containing a polyoxymethylene spring core loaded with 10% w/w dapivirine provided continuous and controlled release of dapivirine over a 6-month period, with a mean in vitro daily release rate of 174 mcg/day. The mechanical properties of the new diaphragm were closely matched to the SILCS diaphragm. The study demonstrates proof of concept for a dapivirine-releasing diaphragm with daily release quantities potentially capable of preventing HIV transmission. In discontinuous clinical use, release of dapivirine may be readily extended over 1 or more years. Copyright © 2013 Elsevier Inc. All rights reserved.

Solar Thermal Energy Storage Device: Hybrid Nanostructures for High-Energy-Density Solar Thermal Fuels

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

2012-01-09

HEATS Project: MIT is developing a thermal energy storage device that captures energy from the sun; this energy can be stored and released at a later time when it is needed most. Within the device, the absorption of sunlight causes the solar thermal fuel’s photoactive molecules to change shape, which allows energy to be stored within their chemical bonds. A trigger is applied to release the stored energy as heat, where it can be converted into electricity or used directly as heat. The molecules would then revert to their original shape, and can be recharged using sunlight to begin themore » process anew. MIT’s technology would be 100% renewable, rechargeable like a battery, and emissions-free. Devices using these solar thermal fuels—called Hybrisol—can also be used without a grid infrastructure for applications such as de-icing, heating, cooking, and water purification.« less

A new way towards high-efficiency thermally activated delayed fluorescence devices via external heavy-atom effect

NASA Astrophysics Data System (ADS)

Zhang, Wenzhi; Jin, Jiangjiang; Huang, Zhi; Zhuang, Shaoqing; Wang, Lei

2016-07-01

Thermally activated delayed fluorescence (TADF) mechanism is a significant method that enables the harvesting of both triplet and singlet excitons for emission. However, up to now most efforts have been devoted to dealing with the relation between singlet-triplet splitting (ΔEST) and fluorescence efficiency, while the significance of spin-orbit coupling (SOC) is usually ignored. In this contribution, a new method is developed to realize high-efficiency TADF-based devices through simple device-structure optimizations. By inserting an ultrathin external heavy-atom (EHA) perturber layer in a desired manner, it provides useful means of accelerating the T1 → S1 reverse intersystem crossing (RISC) in TADF molecules without affecting the corresponding S1 → T1 process heavily. Furthermore, this strategy also promotes the utilization of host triplets through Förster mechanism during host → guest energy transfer (ET) processes, which helps to get rid of the solely dependence upon Dexter mechanism. Based on this strategy, we have successfully raised the external quantum efficiency (EQE) in 4CzPN-based devices by nearly 38% in comparison to control devices. These findings provide keen insights into the role of EHA played in TADF-based devices, offering valuable guidelines for utilizing certain TADF dyes which possess high radiative transition rate but relatively inefficient RISC.

Mechanically Stretchable and Electrically Insulating Thermal Elastomer Composite by Liquid Alloy Droplet Embedment

PubMed Central

Jeong, Seung Hee; Chen, Si; Huo, Jinxing; Gamstedt, Erik Kristofer; Liu, Johan; Zhang, Shi-Li; Zhang, Zhi-Bin; Hjort, Klas; Wu, Zhigang

2015-01-01

Stretchable electronics and soft robotics have shown unsurpassed features, inheriting remarkable functions from stretchable and soft materials. Electrically conductive and mechanically stretchable materials based on composites have been widely studied for stretchable electronics as electrical conductors using various combinations of materials. However, thermally tunable and stretchable materials, which have high potential in soft and stretchable thermal devices as interface or packaging materials, have not been sufficiently studied. Here, a mechanically stretchable and electrically insulating thermal elastomer composite is demonstrated, which can be easily processed for device fabrication. A liquid alloy is embedded as liquid droplet fillers in an elastomer matrix to achieve softness and stretchability. This new elastomer composite is expected useful to enhance thermal response or efficiency of soft and stretchable thermal devices or systems. The thermal elastomer composites demonstrate advantages such as thermal interface and packaging layers with thermal shrink films in transient and steady-state cases and a stretchable temperature sensor. PMID:26671673

High Thermal Rectifications Using Liquid Crystals Confined into a Conical Frustum

NASA Astrophysics Data System (ADS)

Silva, José Guilherme; Fumeron, Sébastien; Moraes, Fernando; Pereira, Erms

2018-05-01

In recent years, phononics, that studies thermal analogs of electronic devices, has become an important subject due to the need for better use of energy resources influenced by growing demand. On developing of these analogs, for example, thermal diodes, a successful route is the design of nanostructured materials (e.g., carbon nanotubes). However, these materials entail increased costs due to the use of complex techniques/equipments, while alternative cheaper materials present nearly comparable efficiency. In this work, we investigate how a thermal diode made by an alternative material (nematic liquid crystal), confined in a conical frustum capillary, can be optimized to achieve high rectifications. In such capillary tube, the thermotropic nematic liquid crystal 5CB produces an axially anisotropic defect called escaped radial disclination. With the molecular director field of such structure, we obtain the thermal conductivity tensor of the diode and solve the steady-state regime of Laplace and Fourier equations using the finite element method. We observed the anisotropy of the system with the non-linear temperature dependences of the molecular thermal conductivities that rectify the heat flux at rates up to 1266% at room temperature. Studying the sensitivity of the system with respect to shape and molecular and thermal aspects, we found that the improved thermal diode is suitable to be miniaturized and applied on well-determined areas, and it is robust against variations of the inward pumped heat flux. This work contributes to the usage of liquid crystals in non-display devices, having potential applications on controlling the heat flux through surfaces.

Thermal management of VECSELs by front surface direct liquid cooling

NASA Astrophysics Data System (ADS)

Smyth, Conor J. C.; Mirkhanov, Shamil; Quarterman, Adrian H.; Wilcox, Keith G.

2016-03-01

Efficient thermal management is vital for VECSELs, affecting the output power and several aspects of performance of the device. Presently there exist two distinct methods of effective thermal management which both possess their merits and disadvantages. Substrate removal of the VECSEL gain chip has proved a successful method in devices emitting at a wavelength near 1μm. However for other wavelengths the substrate removal technique has proved less effective primarily due to the thermal impedance of the distributed Bragg reflectors. The second method of thermal management involves the use of crystalline heat spreaders bonded to the gain chip surface. Although this is an effective thermal management scheme, the disadvantages are additional loss and the etalon effect that filters the gain spectrum, making mode locking more difficult and normally resulting in multiple peaks in the spectrum. There are considerable disadvantages associated with both methods attributed to heatspreader cost and sample processing. It is for these reasons that a proposed alternative, front surface liquid cooling, has been investigated in this project. Direct liquid cooling involves flowing a temperature-controlled liquid over the sample's surface. In this project COMSOL was used to model surface liquid cooling of a VECSEL sample in order to investigate and compare its potential thermal management with current standard thermal management techniques. Based on modelling, experiments were carried out in order to evaluate the performance of the technique. While modelling suggests that this is potentially a mid-performance low cost alternative to existing techniques, experimental measurements to date do not reflect the performance predicted from modelling.

Effects of Thermal Resistance on One-Dimensional Thermal Analysis of the Epidermal Flexible Electronic Devices Integrated with Human Skin

NASA Astrophysics Data System (ADS)

Li, He; Cui, Yun

2017-12-01

Nowadays, flexible electronic devices are increasingly used in direct contact with human skin to monitor the real-time health of human body. Based on the Fourier heat conduction equation and Pennes bio-heat transfer equation, this paper deduces the analytical solutions of one - dimensional heat transfer for flexible electronic devices integrated with human skin under the condition of a constant power. The influence of contact thermal resistance between devices and skin is considered as well. The corresponding finite element model is established to verify the correctness of analytical solutions. The results show that the finite element analysis agrees well with the analytical solution. With bigger thermal resistance, temperature increase of skin surface will decrease. This result can provide guidance for the design of flexible electronic devices to reduce the negative impact that exceeding temperature leave on human skin.

Metal-Organic-Inorganic Nanocomposite Thermal Interface Materials with Ultralow Thermal Resistances.

PubMed

Yegin, Cengiz; Nagabandi, Nirup; Feng, Xuhui; King, Charles; Catalano, Massimo; Oh, Jun Kyun; Talib, Ansam J; Scholar, Ethan A; Verkhoturov, Stanislav V; Cagin, Tahir; Sokolov, Alexei V; Kim, Moon J; Matin, Kaiser; Narumanchi, Sreekant; Akbulut, Mustafa

2017-03-22

As electronic devices get smaller and more powerful, energy density of energy storage devices increases continuously, and moving components of machinery operate at higher speeds, the need for better thermal management strategies is becoming increasingly important. The removal of heat dissipated during the operation of electronic, electrochemical, and mechanical devices is facilitated by high-performance thermal interface materials (TIMs) which are utilized to couple devices to heat sinks. Herein, we report a new class of TIMs involving the chemical integration of boron nitride nanosheets (BNNS), soft organic linkers, and a copper matrix-which are prepared by the chemisorption-coupled electrodeposition approach. These hybrid nanocomposites demonstrate bulk thermal conductivities ranging from 211 to 277 W/(m K), which are very high considering their relatively low elastic modulus values on the order of 21.2-28.5 GPa. The synergistic combination of these properties led to the ultralow total thermal resistivity values in the range of 0.38-0.56 mm 2 K/W for a typical bond-line thickness of 30-50 μm, advancing the current state-of-art transformatively. Moreover, its coefficient of thermal expansion (CTE) is 11 ppm/K, forming a mediation zone with a low thermally induced axial stress due to its close proximity to the CTE of most coupling surfaces needing thermal management.

Preparation and characterization of silica-coated ZnSe nanowires with thermal stability and photoluminescence.

PubMed

Xiong, Shenglin; Xi, Baojuan; Wang, Weizhi; Zhou, Hongyang; Zhang, Shuyuan; Qian, Yitai

2007-12-01

Silica-coated ZnSe nanowires with well-controlled the thickness of sheath in the range of 10-60 nm have been synthesized through a simple sol-gel process. The thickness of silica coating could be controlled through altering reaction parameters such as volume ratio of TEOS and ammonia. XRD, high-resolution TEM, X-ray photoelectron spectroscopy (XPS), Raman spectra, thermogravimetric analysis (TGA), and photoluminescence (PL) spectra were used to characterize the core/sheath nanostructures. Room-temperature PL measurements indicate these silica-coated ZnSe nanowires remarkably improve the PL intensity. Meanwhile, the thermal stability has been enhanced greatly, which is useful for their potential applications in advanced semiconductor devices.

Optical processing for semiconductor device fabrication

NASA Technical Reports Server (NTRS)

Sopori, Bhushan L.

1994-01-01

A new technique for semiconductor device processing is described that uses optical energy to produce local heating/melting in the vicinity of a preselected interface of the device. This process, called optical processing, invokes assistance of photons to enhance interface reactions such as diffusion and melting, as compared to the use of thermal heating alone. Optical processing is performed in a 'cold wall' furnace, and requires considerably lower energies than furnace or rapid thermal annealing. This technique can produce some device structures with unique properties that cannot be produced by conventional thermal processing. Some applications of optical processing involving semiconductor-metal interfaces are described.

Understanding and controlling morphology evolution via DIO plasticization in PffBT4T-2OD/PC71BM devices

PubMed Central

Zhang, Yiwei; Parnell, Andrew J.; Pontecchiani, Fabio; Cooper, Joshaniel F. K.; Thompson, Richard L.; Jones, Richard A. L.; King, Stephen M.; Lidzey, David G.; Bernardo, Gabriel

2017-01-01

We demonstrate that the inclusion of a small amount of the co-solvent 1,8-diiodooctane in the preparation of a bulk-heterojunction photovoltaic device increases its power conversion efficiency by 20%, through a mechanism of transient plasticisation. We follow the removal of 1,8-diiodooctane directly after spin-coating using ellipsometry and ion beam analysis, while using small angle neutron scattering to characterise the morphological nanostructure evolution of the film. In PffBT4T-2OD/PC71BM devices, the power conversion efficiency increases from 7.2% to above 8.7% as a result of the coarsening of the phase domains. This coarsening process is assisted by thermal annealing and the slow evaporation of 1,8-diiodooctane, which we suggest, acts as a plasticiser to promote molecular mobility. Our results show that 1,8-diiodooctane can be completely removed from the film by a thermal annealing process at temperatures ≤100 °C and that there is an interplay between the evaporation rate of 1,8-diiodooctane and the rate of domain coarsening in the plasticized film which helps elucidate the mechanism by which additives improve device efficiency. PMID:28287164

Flow-Boiling Critical Heat Flux Experiments Performed in Reduced Gravity

NASA Technical Reports Server (NTRS)

Hasan, Mohammad M.; Mudawar, Issam

2005-01-01

Poor understanding of flow boiling in microgravity has recently emerged as a key obstacle to the development of many types of power generation and advanced life support systems intended for space exploration. The critical heat flux (CHF) is perhaps the most important thermal design parameter for boiling systems involving both heatflux-controlled devices and intense heat removal. Exceeding the CHF limit can lead to permanent damage, including physical burnout of the heat-dissipating device. The importance of the CHF limit creates an urgent need to develop predictive design tools to ensure both the safe and reliable operation of a two-phase thermal management system under the reduced-gravity (like that on the Moon and Mars) and microgravity environments of space. At present, very limited information is available on flow-boiling heat transfer and the CHF under these conditions.

Electrical Maxwell Demon and Szilard Engine Utilizing Johnson Noise, Measurement, Logic and Control

PubMed Central

Kish, Laszlo Bela; Granqvist, Claes-Göran

2012-01-01

We introduce a purely electrical version of Maxwell's demon which does not involve mechanically moving parts such as trapdoors, etc. It consists of a capacitor, resistors, amplifiers, logic circuitry and electronically controlled switches and uses thermal noise in resistors (Johnson noise) to pump heat. The only types of energy of importance in this demon are electrical energy and heat. We also demonstrate an entirely electrical version of Szilard's engine, i.e., an information-controlled device that can produce work by employing thermal fluctuations. The only moving part is a piston that executes work, and the engine has purely electronic controls and it is free of the major weakness of the original Szilard engine in not requiring removal and repositioning the piston at the end of the cycle. For both devices, the energy dissipation in the memory and other binary informatics components are insignificant compared to the exponentially large energy dissipation in the analog part responsible for creating new information by measurement and decision. This result contradicts the view that the energy dissipation in the memory during erasure is the most essential dissipation process in a demon. Nevertheless the dissipation in the memory and information processing parts is sufficient to secure the Second Law of Thermodynamics. PMID:23077525

Electrical Maxwell demon and Szilard engine utilizing Johnson noise, measurement, logic and control.

PubMed

Kish, Laszlo Bela; Granqvist, Claes-Göran

2012-01-01

We introduce a purely electrical version of Maxwell's demon which does not involve mechanically moving parts such as trapdoors, etc. It consists of a capacitor, resistors, amplifiers, logic circuitry and electronically controlled switches and uses thermal noise in resistors (Johnson noise) to pump heat. The only types of energy of importance in this demon are electrical energy and heat. We also demonstrate an entirely electrical version of Szilard's engine, i.e., an information-controlled device that can produce work by employing thermal fluctuations. The only moving part is a piston that executes work, and the engine has purely electronic controls and it is free of the major weakness of the original Szilard engine in not requiring removal and repositioning the piston at the end of the cycle. For both devices, the energy dissipation in the memory and other binary informatics components are insignificant compared to the exponentially large energy dissipation in the analog part responsible for creating new information by measurement and decision. This result contradicts the view that the energy dissipation in the memory during erasure is the most essential dissipation process in a demon. Nevertheless the dissipation in the memory and information processing parts is sufficient to secure the Second Law of Thermodynamics.

Lih thermal energy storage device

DOEpatents

Olszewski, Mitchell; Morris, David G.

1994-01-01

A thermal energy storage device for use in a pulsed power supply to store waste heat produced in a high-power burst operation utilizes lithium hydride as the phase change thermal energy storage material. The device includes an outer container encapsulating the lithium hydride and an inner container supporting a hydrogen sorbing sponge material such as activated carbon. The inner container is in communication with the interior of the outer container to receive hydrogen dissociated from the lithium hydride at elevated temperatures.

Thermal Remote Anemometer Device

NASA Technical Reports Server (NTRS)

Heyman, Joseph S.; Heath, D. Michele; Winfree, William P.; Miller, William E.; Welch, Christopher S.

1988-01-01

Thermal Remote Anemometer Device developed for remote, noncontacting, passive measurement of thermal properties of sample. Model heated locally by scanning laser beam and cooled by wind in tunnel. Thermal image of model analyzed to deduce pattern of airflow around model. For materials applications, system used for evaluation of thin films and determination of thermal diffusivity and adhesive-layer contact. For medical applications, measures perfusion through skin to characterize blood flow and used to determine viabilities of grafts and to characterize tissues.

System Level Analysis of a Water PCM HX Integrated Into Orion's Thermal Control System Abstract

NASA Technical Reports Server (NTRS)

Navarro, Moses; Hansen, Scott; Ungar, Eugene; Sheth, Rubik

2015-01-01

In a cyclical heat load environment such as low Lunar orbit, a spacecraft's radiators are not sized to reject the full heat load requirement. Traditionally, a supplemental heat rejection device (SHReD) such as an evaporator or sublimator is used to act as a "topper" to meet the additional heat rejection demands. Utilizing a Phase Change Material (PCM) heat exchanger (HX) as a SHReD provides an attractive alternative to evaporators and sublimators as PCM HXs do not use a consumable, thereby leading to reduced launch mass and volume requirements. In continued pursuit of water PCM HX development an Orion system level analysis was performed using Thermal Desktop for a water PCM HX integrated into Orion's thermal control system and in a 100km Lunar orbit. The study analyzed 1) placing the PCM on the Internal Thermal Control System (ITCS) versus the External Thermal Control System (ETCS) 2) use of 30/70 PGW verses 50/50 PGW and 3) increasing the radiator area in order to reduce PCM freeze times. The analysis showed that for the assumed operating and boundary conditions utilizing a water PCM HX on Orion is not a viable option. Additionally, it was found that the radiator area would have to be increased over 20% in order to have a viable water-based PCM HX.

Solar energy thermalization and storage device

DOEpatents

McClelland, J.F.

A passive solar thermalization and thermal energy storage assembly which is visually transparent is described. The assembly consists of two substantial parallel, transparent wall members mounted in a rectangular support frame to form a liquid-tight chamber. A semitransparent thermalization plate is located in the chamber, substantially paralled to and about equidistant from the transparent wall members to thermalize solar radiation which is stored in a transparent thermal energy storage liquid which fills the chamber. A number of the devices, as modules, can be stacked together to construct a visually transparent, thermal storage wall for passive solar-heated buildings.

Nonreciprocal Thermal Material by Spatiotemporal Modulation

NASA Astrophysics Data System (ADS)

Torrent, Daniel; Poncelet, Olivier; Batsale, Jean-Chirstophe

2018-03-01

The thermal properties of a material with a spatiotemporal modulation, in the form of a traveling wave, in both the thermal conductivity and the specific heat capacity are studied. It is found that these materials behave as materials with an internal convectionlike term that provides them with nonreciprocal properties, in the sense that the heat flux has different properties when it propagates in the same direction or in the opposite one to the modulation of the parameters. An effective medium description is presented which accurately describes the modulated material, and numerical simulations support this description and verify the nonreciprocal properties of the material. It is found that these materials are promising candidates for the design of thermal diodes and other advanced devices for the control of the heat flow at all scales.

Micro-scale thermal imaging of advanced organic and polymeric materials

NASA Astrophysics Data System (ADS)

Morikawa, Junko

2012-10-01

Recent topics of micro-scale thermal imaging on advanced organic and polymeric materials are presented, the originally developed IR camera systems equipped with a real time direct impose-signal capturing device and a laser drive generating a modulated spot heating with a diode laser, controlled by the x-y positioning actuator, has been applied to measure the micro-scale thermal phenomena. The advanced organic and polymeric materials are now actively developed especially for the purpose of the effective heat dissipation in the new energy system, including, LED, Lithium battery, Solar cell, etc. The micro-scale thermal imaging in the heat dissipation process has become important in view of the effective power saving. In our system, the imposed temperature data are applied to the pixel emissivity corrections and visualizes the anisotropic thermal properties of the composite materials at the same time. The anisotropic thermal diffusion in the ultra-drawn high-thermal conductive metal-filler composite polymer film and the carbon-cloth for the battery systems are visualized.

Thermal management systems and methods

DOEpatents

Gering, Kevin L.; Haefner, Daryl R.

2006-12-12

A thermal management system for a vehicle includes a heat exchanger having a thermal energy storage material provided therein, a first coolant loop thermally coupled to an electrochemical storage device located within the first coolant loop and to the heat exchanger, and a second coolant loop thermally coupled to the heat exchanger. The first and second coolant loops are configured to carry distinct thermal energy transfer media. The thermal management system also includes an interface configured to facilitate transfer of heat generated by an internal combustion engine to the heat exchanger via the second coolant loop in order to selectively deliver the heat to the electrochemical storage device. Thermal management methods are also provided.

Reversible switching between pressure-induced amorphization and thermal-driven recrystallization in VO2(B) nanosheets

PubMed Central

Wang, Yonggang; Zhu, Jinlong; Yang, Wenge; Wen, Ting; Pravica, Michael; Liu, Zhenxian; Hou, Mingqiang; Fei, Yingwei; Kang, Lei; Lin, Zheshuai; Jin, Changqing; Zhao, Yusheng

2016-01-01

Pressure-induced amorphization (PIA) and thermal-driven recrystallization have been observed in many crystalline materials. However, controllable switching between PIA and a metastable phase has not been described yet, due to the challenge to establish feasible switching methods to control the pressure and temperature precisely. Here, we demonstrate a reversible switching between PIA and thermally-driven recrystallization of VO2(B) nanosheets. Comprehensive in situ experiments are performed to establish the precise conditions of the reversible phase transformations, which are normally hindered but occur with stimuli beyond the energy barrier. Spectral evidence and theoretical calculations reveal the pressure–structure relationship and the role of flexible VOx polyhedra in the structural switching process. Anomalous resistivity evolution and the participation of spin in the reversible phase transition are observed for the first time. Our findings have significant implications for the design of phase switching devices and the exploration of hidden amorphous materials. PMID:27426219

Assessment of Alphamagnetic Spectrometer (AMS) Upper Experiment Structural Configuration Shielding Effectiveness Associated with Change from Cryo-Cooled Magnet to Permanent Magnet

NASA Technical Reports Server (NTRS)

Scully, Robert

2012-01-01

In the spring of 2010, the Alpha Magnetic Spectrometer 2 (AMS-02) underwent a series of system level electromagnetic interference control measurements, followed by thermal vacuum testing. Shortly after completion of the thermal vacuum testing, the project decided to remove the cryogenically cooled superconducting magnet, and replace it with the original permanent magnet design employed in the earlier AMS- 01 assembly. Doing so necessitated several structural changes, as well as removal or modification of numerous electronic and thermal control devices and systems. At this stage, the project was rapidly approaching key milestone dates for hardware completion and delivery for launch, and had little time for additional testing or assessment of any impact to the electromagnetic signature of the AMS-02. Therefore, an analytical assessment of the radiated emissions behavioural changes associated with the system changes was requested.

Reversible switching between pressure-induced amorphization and thermal-driven recrystallization in VO2(B) nanosheets.

PubMed

Wang, Yonggang; Zhu, Jinlong; Yang, Wenge; Wen, Ting; Pravica, Michael; Liu, Zhenxian; Hou, Mingqiang; Fei, Yingwei; Kang, Lei; Lin, Zheshuai; Jin, Changqing; Zhao, Yusheng

2016-07-18

Pressure-induced amorphization (PIA) and thermal-driven recrystallization have been observed in many crystalline materials. However, controllable switching between PIA and a metastable phase has not been described yet, due to the challenge to establish feasible switching methods to control the pressure and temperature precisely. Here, we demonstrate a reversible switching between PIA and thermally-driven recrystallization of VO2(B) nanosheets. Comprehensive in situ experiments are performed to establish the precise conditions of the reversible phase transformations, which are normally hindered but occur with stimuli beyond the energy barrier. Spectral evidence and theoretical calculations reveal the pressure-structure relationship and the role of flexible VOx polyhedra in the structural switching process. Anomalous resistivity evolution and the participation of spin in the reversible phase transition are observed for the first time. Our findings have significant implications for the design of phase switching devices and the exploration of hidden amorphous materials.

Effect of solvent and subsequent thermal annealing on the performance of phenylenevinylene copolymer: PCBM solar cells.

PubMed

Sharma, G D; Suresh, P; Sharma, S S; Vijay, Y K; Mikroyannidis, John A

2010-02-01

The morphology of the photoactive layer used in the bulk heterojunction photovoltaic devices is crucial for efficient charge generation and their collection at the electrodes. We investigated the solvent vapor annealing and thermal annealing effect of an alternating phenylenevinylene copolymer P:PCBM blend on its morphology and optical properties. The UV-visible absorption spectroscopy shows that both solvent and thermal annealing can result in self-assembling of copolymer P to form an ordered structure, leading to enhanced absorption in the red region and hole transport enhancement. By combining the solvent and thermal annealing of the devices, the power conversion efficiency is improved. This feature was attributed to the fact that the PCBM molecules begin to diffuse into aggregates and together with the ordered copolymer P phase form bicontinuous pathways in the entire layer for efficient charge separation and transport. Furthermore, the measured photocurrent also suggests that the space charges no longer limit the values of the short circuit current (J(sc)) and fill factor (FF) for solvent-treated and thermally annealed devices. These results indicate that the higher J(sc) and PCE for the solvent-treated and thermally annealed devices can be attributed to the phase separation of active layers, which leads to a balanced carrier mobility. The overall PCE of the device based on the combination of solvent annealing and thermal annealing is about 3.7 %.

Methods of measurement for semiconductor materials, process control, and devices

NASA Technical Reports Server (NTRS)

Bullis, W. M. (Editor)

1973-01-01

This progress report describes NBS activities directed toward the development of methods of measurement for semiconductor materials, process control, and devices. Significant accomplishments during this reporting period include design of a plan to provide standard silicon wafers for four-probe resistivity measurements for the industry, publication of a summary report on the photoconductive decay method for measuring carrier lifetime, publication of a comprehensive review of the field of wire bond fabrication and testing, and successful completion of organizational activity leading to the establishment of a new group on quality and hardness assurance in ASTM Committee F-1 on Electronics. Work is continuing on measurement of resistivity of semiconductor crystals; characterization of generation-recombination-trapping centers in silicon; study of gold-doped silicon; development of the infrared response technique; evaluation of wire bonds and die attachment; and measurement of thermal properties of semiconductor devices, delay time and related carrier transport properties in junction devices, and noise properties of microwave diodes.

Tutorial: Determination of thermal boundary resistance by molecular dynamics simulations

NASA Astrophysics Data System (ADS)

Liang, Zhi; Hu, Ming

2018-05-01

Due to the high surface-to-volume ratio of nanostructured components in microelectronics and other advanced devices, the thermal resistance at material interfaces can strongly affect the overall thermal behavior in these devices. Therefore, the thermal boundary resistance, R, must be taken into account in the thermal analysis of nanoscale structures and devices. This article is a tutorial on the determination of R and the analysis of interfacial thermal transport via molecular dynamics (MD) simulations. In addition to reviewing the commonly used equilibrium and non-equilibrium MD models for the determination of R, we also discuss several MD simulation methods which can be used to understand interfacial thermal transport behavior. To illustrate how these MD models work for various interfaces, we will show several examples of MD simulation results on thermal transport across solid-solid, solid-liquid, and solid-gas interfaces. The advantages and drawbacks of a few other MD models such as approach-to-equilibrium MD and first-principles MD are also discussed.

Thermal energy and charge currents in multi-terminal nanorings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kramer, Tobias; Konrad-Zuse-Zentrum für Informationstechnik Berlin, 14195 Berlin; Kreisbeck, Christoph

2016-06-15

We study in experiment and theory thermal energy and charge transfer close to the quantum limit in a ballistic nanodevice, consisting of multiply connected one-dimensional electron waveguides. The fabricated device is based on an AlGaAs/GaAs heterostructure and is covered by a global top-gate to steer the thermal energy and charge transfer in the presence of a temperature gradient, which is established by a heating current. The estimate of the heat transfer by means of thermal noise measurements shows the device acting as a switch for charge and thermal energy transfer. The wave-packet simulations are based on the multi-terminal Landauer-Büttiker approachmore » and confirm the experimental finding of a mode-dependent redistribution of the thermal energy current, if a scatterer breaks the device symmetry.« less

Heat conduction tuning by hyperbranched nanophononic metamaterials

NASA Astrophysics Data System (ADS)

Li, Bing; Tan, K. T.; Christensen, Johan

2018-05-01

Phonon dispersion and thermal conduction properties of hyperbranched nanostructures with unique topological complexity are theoretically and numerically investigated in this research. We present analytical cantilever-in-mass models to analyze and control the inherent resonance hybridization in hyperbranched nanomembranes containing different configurations and cross sections. We show that these local resonances hosted by hyperbranched nanopillars can generate numerous flat bands in the phonon dispersion relation and dramatically lower the group velocities, consequently resulting in a significant reduction of the thermal conductivity. The applicability of the proposed analytical models in thermal conductivity tuning is demonstrated, and a superior performance in reducing the heat flux in nano-structured membranes is exhibited, which can potentially lead to improved thermoelectric energy conversion devices.

A variable conductance gas switch for intermediate temperature operation of liquid He/liquid N2 cryostats

NASA Technical Reports Server (NTRS)

Rayner, J. T.; Chuter, T. C.; Mclean, I. S.; Radostitz, J. V.; Nolt, I. G.

1988-01-01

A technique for establishing a stable intermediate temperature stage in liquid He/liquid N2 double vessel cryostats is described. The tertiary cold stage, which can be tuned to any temperature between 10 and 60 K, is ideal for cooling IR sensors for use in astronomy and physics applications. The device is called a variable-conductance gas switch. It is essentially a small chamber, located between the cold stage and liquid helium cold-face, whose thermal conductance may be controlled by varying the pressure of helium gas within the chamber. A key feature of this device is the large range of temperature control achieved with a very small (less than 10 mW) heat input from the cryogenic temperature control switch.

LiH thermal energy storage device

DOEpatents

Olszewski, M.; Morris, D.G.

1994-06-28

A thermal energy storage device for use in a pulsed power supply to store waste heat produced in a high-power burst operation utilizes lithium hydride as the phase change thermal energy storage material. The device includes an outer container encapsulating the lithium hydride and an inner container supporting a hydrogen sorbing sponge material such as activated carbon. The inner container is in communication with the interior of the outer container to receive hydrogen dissociated from the lithium hydride at elevated temperatures. 5 figures.

THERMAL TREATMENT OF 1,2,3,4-TETRACHLORODIBENZO-P- DIOXIN BY REACTION WITH CA-BASED SORBENTS AT 23-300 DEGREES °C

EPA Science Inventory

The fate of combustion-generated polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans captured in sorbent-based, air pollution control devices remains uncertain. This process was simulated by passing vapor-phase 1,2,3,4-tetrachlorinated dibenzo-p-dioxin (TCDD) to a...

40 CFR 63.5994 - How do I conduct tests and procedures for tire production affected sources?

Code of Federal Regulations, 2014 CFR

2014-07-01

... oxidizer, monitor the firebox secondary chamber temperature. (ii) If you use a carbon adsorber, monitor the total regeneration stream mass or volumetric flow for each regeneration cycle, and the carbon bed... control device other than a thermal oxidizer or a regenerative carbon adsorber, install and operate a...

Methods of forming thermal management systems and thermal management methods

DOEpatents

Gering, Kevin L.; Haefner, Daryl R.

2012-06-05

A thermal management system for a vehicle includes a heat exchanger having a thermal energy storage material provided therein, a first coolant loop thermally coupled to an electrochemical storage device located within the first coolant loop and to the heat exchanger, and a second coolant loop thermally coupled to the heat exchanger. The first and second coolant loops are configured to carry distinct thermal energy transfer media. The thermal management system also includes an interface configured to facilitate transfer of heat generated by an internal combustion engine to the heat exchanger via the second coolant loop in order to selectively deliver the heat to the electrochemical storage device. Thermal management methods are also provided.

Strain-engineered growth of two-dimensional materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ahn, Geun Ho; Amani, Matin; Rasool, Haider

The application of strain to semiconductors allows for controlled modification of their band structure. This principle is employed for the manufacturing of devices ranging from high-performance transistors to solid-state lasers. Traditionally, strain is typically achieved via growth on lattice-mismatched substrates. For two-dimensional (2D) semiconductors, this is not feasible as they typically do not interact epitaxially with the substrate. Here in this paper, we demonstrate controlled strain engineering of 2D semiconductors during synthesis by utilizing the thermal coefficient of expansion mismatch between the substrate and semiconductor. Using WSe 2 as a model system, we demonstrate stable built-in strains ranging from 1%more » tensile to 0.2% compressive on substrates with different thermal coefficient of expansion. Consequently, we observe a dramatic modulation of the band structure, manifested by a strain-driven indirect-to-direct bandgap transition and brightening of the dark exciton in bilayer and monolayer WSe 2, respectively. The growth method developed here should enable flexibility in design of more sophisticated devices based on 2D materials.« less

Strain-engineered growth of two-dimensional materials

DOE PAGES

Ahn, Geun Ho; Amani, Matin; Rasool, Haider; ...

2017-09-20

The application of strain to semiconductors allows for controlled modification of their band structure. This principle is employed for the manufacturing of devices ranging from high-performance transistors to solid-state lasers. Traditionally, strain is typically achieved via growth on lattice-mismatched substrates. For two-dimensional (2D) semiconductors, this is not feasible as they typically do not interact epitaxially with the substrate. Here in this paper, we demonstrate controlled strain engineering of 2D semiconductors during synthesis by utilizing the thermal coefficient of expansion mismatch between the substrate and semiconductor. Using WSe 2 as a model system, we demonstrate stable built-in strains ranging from 1%more » tensile to 0.2% compressive on substrates with different thermal coefficient of expansion. Consequently, we observe a dramatic modulation of the band structure, manifested by a strain-driven indirect-to-direct bandgap transition and brightening of the dark exciton in bilayer and monolayer WSe 2, respectively. The growth method developed here should enable flexibility in design of more sophisticated devices based on 2D materials.« less

Relationship between tissue tension and thermal diffusion to peripheral tissue using an energy device.

PubMed

Kondo, Akihiro; Nishizawa, Yuji; Ito, Masaaki; Saito, Norio; Fujii, Satoshi; Akamoto, Shintaro; Fujiwara, Masao; Okano, Keiichi; Suzuki, Yasuyuki

2016-08-01

The aim of the study was to assess the relationship between tissue tension and thermal diffusion to peripheral tissues using an electric scalpel, ultrasonically activated device, or a bipolar sealing system. The mesentery of pigs was excised with each energy device (ED) at three tissue tensions (0, 300, 600 g). The excision time and thermal diffusion area were monitored with thermography, measured for each ED, and then histologically examined. Correlations between tissue tension and thermal diffusion area were examined. The excision time was inversely correlated with tissue tension for all ED (electric scalpel, r = 0.718; ultrasonically activated device, r = 0.949; bipolar sealing system, r = 0.843), and tissue tension was inversely correlated with the thermal diffusion area with the electric scalpel (r = 0.718) and bipolar sealing system (r = 0.869). Histopathologically, limited deep thermal denaturation occurred at a tension of 600 g with all ED. We conclude that thermal damage can be avoided with adequate tissue tension when any ED is used. © 2016 Japan Society for Endoscopic Surgery, Asia Endosurgery Task Force and John Wiley & Sons Australia, Ltd.

[Test of thermal deformation for electronic devices of high thermal reliability].

PubMed

Li, Hai-yuan; Li, Bao-ming

2002-06-01

Thermal deformation can be caused by high partial heat flux and greatly reduce thermal reliability of electronic devices. In this paper, an attempt is made to measure the thermal deformation of high power electronic devices under working condition using laser holographic interferometry with double exposure. Laser holographic interferometry is an untouched measurement with measurement precision up to micron dimension. The electronic device chosen for measurement is a type of solid state relay which is used for ignition of rockets. The output circuit of the solid state relay is made up of a MOSFET chip and the power density of the chip can reach high value. In particular situations thermal deformation and stress may significantly influence working performance of the solid state relay. The bulk deformation of the chip and its mount is estimated by number of interferential stripes on chip surface. While thermal stress and deformation can be estimated by curvature of interferential stripes on chip surface. Experimental results indicate that there are more interferential stripes on chip surface and greater flexural degree of stripes under high power. Therefore, these results reflect large out-of-plain displacement and deformed size of the chip with the increase of load current.

Carbon nanotube vacuum gauges utilizing long, dissipative tubes

NASA Astrophysics Data System (ADS)

Kaul, Anupama B.; Manohara, Harish M.

2008-04-01

A carbon nanotube-based thermal conductivity vacuum gauge is described which utilizes 5-10 μm long diffusively contacted SWNTs for vacuum sensing. By etching the thermal SiO II beneath the tubes and minimizing heat conduction through the substrate, pressure sensitivity was extended toward higher vacuums. The pressure response of unannealed and annealed devices was compared to that of released devices. The released devices showed sensitivity to pressure as low as 1 x 10 -6 Torr. The sensitivity increased more dramatically with power for the released device compared to that of the unreleased device. Low temperature electronic transport measurements of the tubes were suggestive of a thermally activated hopping mechanism where the activation energy for hopping was calculated to be ~ 39 meV.

Thermodynamic Vent System for an On-Orbit Cryogenic Reaction Control Engine

NASA Technical Reports Server (NTRS)

Hurlbert, Eric A.; Romig, Kris A.; Jimenez, Rafael; Flores, Sam

2012-01-01

A report discusses a cryogenic reaction control system (RCS) that integrates a Joule-Thompson (JT) device (expansion valve) and thermodynamic vent system (TVS) with a cryogenic distribution system to allow fine control of the propellant quality (subcooled liquid) during operation of the device. It enables zero-venting when coupled with an RCS engine. The proper attachment locations and sizing of the orifice are required with the propellant distribution line to facilitate line conditioning. During operations, system instrumentation was strategically installed along the distribution/TVS line assembly, and temperature control bands were identified. A sub-scale run tank, full-scale distribution line, open-loop TVS, and a combination of procured and custom-fabricated cryogenic components were used in the cryogenic RCS build-up. Simulated on-orbit activation and thruster firing profiles were performed to quantify system heat gain and evaluate the TVS s capability to maintain the required propellant conditions at the inlet to the engine valves. Test data determined that a small control valve, such as a piezoelectric, is optimal to provide continuously the required thermal control. The data obtained from testing has also assisted with the development of fluid and thermal models of an RCS to refine integrated cryogenic propulsion system designs. This system allows a liquid oxygenbased main propulsion and reaction control system for a spacecraft, which improves performance, safety, and cost over conventional hypergolic systems due to higher performance, use of nontoxic propellants, potential for integration with life support and power subsystems, and compatibility with in-situ produced propellants.

Printable, flexible and stretchable diamond for thermal management

DOEpatents

Rogers, John A; Kim, Tae Ho; Choi, Won Mook; Kim, Dae Hyeong; Meitl, Matthew; Menard, Etienne; Carlisle, John

2013-06-25

Various heat-sinked components and methods of making heat-sinked components are disclosed where diamond in thermal contact with one or more heat-generating components are capable of dissipating heat, thereby providing thermally-regulated components. Thermally conductive diamond is provided in patterns capable of providing efficient and maximum heat transfer away from components that may be susceptible to damage by elevated temperatures. The devices and methods are used to cool flexible electronics, integrated circuits and other complex electronics that tend to generate significant heat. Also provided are methods of making printable diamond patterns that can be used in a range of devices and device components.

Electrically-controlled near-field radiative thermal modulator made of graphene-coated silicon carbide plates

NASA Astrophysics Data System (ADS)

Yang, Yue; Wang, Liping

2017-08-01

In this work, we propose a hybrid near-field radiative thermal modulator made of two graphene-covered silicon carbide (SiC) plates separated by a nanometer vacuum gap. The near-field photon tunneling between the emitter and receiver is modulated by changing graphene chemical potentials with symmetrically or asymmetrically applied voltage biases. The radiative heat flux calculated from fluctuational electrodynamics significantly varies with graphene chemical potentials due to tunable near-field coupling strength between graphene plasmons across the vacuum gap. Thermal modulation and switching, which are the key functionalities required for a thermal modulator, are theoretically realized and analyzed. Newly introduced quantities of the modulation factor, the sensitivity factor and switching factor are studied quite extensively in a large parameter range for both graphene chemical potential and vacuum gap distance. This opto-electronic device with faster operating mode, which is in principle only limited by electronics and not by the thermal inertia, will facilitate the practical application of active thermal management, thermal circuits, and thermal computing with photon-based near-field thermal transport.

A Device to Emulate Diffusion and Thermal Conductivity Using Water Flow

ERIC Educational Resources Information Center

Blanck, Harvey F.

2005-01-01

A device designed to emulate diffusion and thermal conductivity using flowing water is reviewed. Water flowing through a series of cells connected by a small tube in each partition in this plastic model is capable of emulating diffusion and thermal conductivity that occurs in variety of systems described by several mathematical equations.

There's an app for that: A handheld smartphone-based infrared imaging device to assess adequacy and level of aortic occlusion during REBOA.

PubMed

Sokol, Kyle K; Black, George E; Willey, Sandra B; Kniery, Kevin; Marko, Shannon T; Eckert, Matthew J; Martin, Matthew J

2017-01-01

Advances in thermal imaging devices have made them an appealing noninvasive point-of-care imaging adjunct in the trauma setting. We sought to assess whether a smartphone-based infrared imaging device (SBIR) could determine presence and location of aortic occlusion in a swine model. We hypothesized that various levels of aortic occlusion would transmit significantly different heat signatures at various anatomical points. Six swine (35-50 kg) underwent sequential zone 1 (Z1) aortic cross clamping as well as zone 3 (Z3) aortic balloon occlusion (resuscitative endovascular balloon occlusion of the aorta [REBOA]). SBIR images and readings (FLIR One) were taken at five anatomic points (axilla [A], subcostal [S], umbilical [U], inguinal [I], medial malleolar [M]) and were used to determine significant thermal trends 5 minutes to 10 minutes after Z1 and Z3 occlusion. Significant (p ≤ 0.05) thermal ratio patterns were identified and compared among groups, and images were reviewed for obvious qualitative differences at the various levels of occlusion. Body temperatures were similar during control (CON), Z1 occlusion, and Z3 occlusion, ranging from 94.0 °F to 100.9 °F (p = 0.126). No significant temperature differences were found among A, S, U, I, M points prior to and after aortic occlusions. Among the anatomical 2-point ratios evaluated, A/M and S/M ratios were the best predictors of aortic occlusion, whether at Z1 (8.2 °F, p < 0.01; 10.9 °F, p < 0.01) or Z3 (7.3 °F, p < 0.01; 8.4 °F, p < 0.01), respectively. The best predictor of Z1 versus Z3 level of occlusion was the S/I ratio (5.2 °F, p < 0.05 vs. 3.4 °F, p = 0.27). SBIR generated qualitatively different thermal signatures among groups. SBIR was capable of detecting thermal trends during Z1 and Z3 aortic occlusion by using an anatomical 2-point thermal ratio. There were also easily recognized qualitative differences between control and occlusion images that would allow immediate determination of adequate occlusion of the aorta. SBIR represents a potential inexpensive and accurate tool for assessing perfusion, adequate REBOA placement, and even the aortic level of occlusion.

Advanced Devices for Cryogenic Thermal Management

NASA Astrophysics Data System (ADS)

Bugby, D.; Stouffer, C.; Garzon, J.; Beres, M.; Gilchrist, A.

2006-04-01

This paper describes six advanced cryogenic thermal management devices/subsystems developed by Swales Aerospace for ground/space-based applications of interest to NASA, DoD, and the commercial sector. The devices/subsystems described herein include the following: (a) a differential thermal expansion cryogenic thermal switch (DTE-CTSW) constructed with high purity aluminum end-pieces and an Ultem support rod for the 6 K Mid-Infrared Instrument (MIRI) on the James Webb Space Telescope (JWST) (b) a quad-redundant DTE-CTSW assembly for the 35 K science instruments (NIRCam, NIRSpec, and FGS) mounted on the JWST Integrated Science Instrument Module (ISIM) (c) a cryogenic diode heat pipe (CDHP) thermal switching system using methane as the working fluid for the 100 K CRISM hyperspectral mapping instrument on the Mars Reconnaissance Orbiter (MRO) and (d) three additional devices/subsystems developed during the AFRL-sponsored CRYOTOOL program, which include a dual DTE-CTSW/dual cryocooler test bed, a miniaturized neon cryogenic loop heat pipe (mini-CLHP), and an across gimbal cryogenic thermal transport system (GCTTS). For the first three devices/subsystems mentioned above, this paper describes key aspects of the development efforts including concept definition, design, fabrication, and testing. For the latter three, this paper provides brief overview descriptions as key details are provided in a related paper.

High temperature thermal management with boron nitride nanosheets.

PubMed

Wang, Yilin; Xu, Lisha; Yang, Zhi; Xie, Hua; Jiang, Puqing; Dai, Jiaqi; Luo, Wei; Yao, Yonggang; Hitz, Emily; Yang, Ronggui; Yang, Bao; Hu, Liangbing

2017-12-21

The rapid development of high power density devices requires more efficient heat dissipation. Recently, two-dimensional layered materials have attracted significant interest due to their superior thermal conductivity, ease of production and chemical stability. Among them, hexagonal boron nitride (h-BN) is electrically insulating, making it a promising thermal management material for next-generation electronics. In this work, we demonstrated that an h-BN thin film composed of layer-by-layer laminated h-BN nanosheets can effectively enhance the lateral heat dissipation on the substrate. We found that by using the BN-coated glass instead of bare glass as the substrate, the highest operating temperature of a reduced graphene oxide (RGO) based device could increase from 700 °C to 1000 °C, and at the same input power, the operating temperature of the RGO device is effectively decreased. The remarkable performance improvement using the BN coating originates from its anisotropic thermal conductivity: a high in-plane thermal conductivity of 14 W m -1 K -1 for spreading and a low cross-plane thermal conductivity of 0.4 W m -1 K -1 to avoid a hot spot right underneath the device. Our results provide an effective approach to improve the heat dissipation in integrated circuits and high power devices.

Other Types Of LCDs

NASA Astrophysics Data System (ADS)

Kobayashi, Shunsuke; Mochizuki, Akihiro

The following sections are included: * INTRODUCTION * TUNABLE BIREFRINGENCE LCDs * Nematic Device with Homogeneous Alignment * Nematic Device with Homeotropic Alignment * ELECTRICALLY CONTROLLED BIREFRINGENCE EFFECT LCDs WITH A COMPENSATING CELL OR POLYMER LAYERS * Super Homeotropic LCDs * Black and White STN LCDs * Optical mode interference * Guest-host mode * Double-layered STN * Retardation film compensated STN * DUAL FREQUENCY ADDRESSING LCDs * Application for DSM LCDs * Application for TN LCDs * PI-CELL * CHOLESTERIC-NEMATIC PHASE CHANGE LCDs * Storage Mode LCDs * Stabilized Hysteresis Mode LCDs * THERMALLY ADDRESSED LCDs (CHOLESTERIC) * BISTABLE LCD * WIDE VIEWING ANGLE TN LCDs USING RETARDATION SHEETS * Type 1 Cells * Type 2 Cells * REFERENCES

Tunable electrical conductivity of individual graphene oxide sheets reduced at "low" temperatures.

PubMed

Jung, Inhwa; Dikin, Dmitriy A; Piner, Richard D; Ruoff, Rodney S

2008-12-01

Step-by-step controllable thermal reduction of individual graphene oxide sheets, incorporated into multiterminal field effect devices, was carried out at low temperatures (125-240 degrees C) with simultaneous electrical measurements. Symmetric hysteresis-free ambipolar (electron- and hole-type) gate dependences were observed as soon as the first measurable resistance was reached. The conductivity of each of the fabricated devices depended on the level of reduction (was increased more than 10(6) times as reduction progressed), strength of the external electrical field, density of the transport current, and temperature.

Self-correcting electronically scanned pressure sensor

NASA Technical Reports Server (NTRS)

Gross, C. (Inventor)

1983-01-01

A multiple channel high data rate pressure sensing device is disclosed for use in wind tunnels, spacecraft, airborne, process control, automotive, etc., pressure measurements. Data rates in excess of 100,000 measurements per second are offered with inaccuracies from temperature shifts less than 0.25% (nominal) of full scale over a temperature span of 55 C. The device consists of thirty-two solid state sensors, signal multiplexing electronics to electronically address each sensor, and digital electronic circuitry to automatically correct the inherent thermal shift errors of the pressure sensors and their associated electronics.

Two-dimensional thermal modeling of power monolithic microwave integrated circuits (MMIC's)

NASA Technical Reports Server (NTRS)

Fan, Mark S.; Christou, Aris; Pecht, Michael G.

1992-01-01

Numerical simulations of the two-dimensional temperature distributions for a typical GaAs MMIC circuit are conducted, aiming at understanding the heat conduction process of the circuit chip and providing temperature information for device reliability analysis. The method used is to solve the two-dimensional heat conduction equation with a control-volume-based finite difference scheme. In particular, the effects of the power dissipation and the ambient temperature are examined, and the criterion for the worst operating environment is discussed in terms of the allowed highest device junction temperature.

Assisted Writing in Spin Transfer Torque Magnetic Tunnel Junctions

NASA Astrophysics Data System (ADS)

Ganguly, Samiran; Ahmed, Zeeshan; Datta, Supriyo; Marinero, Ernesto E.

2015-03-01

Spin transfer torque driven MRAM devices are now in an advanced state of development, and the importance of reducing the current requirement for writing information is well recognized. Different approaches to assist the writing process have been proposed such as spin orbit torque, spin Hall effect, voltage controlled magnetic anisotropy and thermal excitation. In this work,we report on our comparative study using the Spin-Circuit Approach regarding the total energy, the switching speed and energy-delay products for different assisted writing approaches in STT-MTJ devices using PMA magnets.

Silicon Carbide Solar Cells Investigated

NASA Technical Reports Server (NTRS)

Bailey, Sheila G.; Raffaelle, Ryne P.

2001-01-01

The semiconductor silicon carbide (SiC) has long been known for its outstanding resistance to harsh environments (e.g., thermal stability, radiation resistance, and dielectric strength). However, the ability to produce device-quality material is severely limited by the inherent crystalline defects associated with this material and their associated electronic effects. Much progress has been made recently in the understanding and control of these defects and in the improved processing of this material. Because of this work, it may be possible to produce SiC-based solar cells for environments with high temperatures, light intensities, and radiation, such as those experienced by solar probes. Electronics and sensors based on SiC can operate in hostile environments where conventional silicon-based electronics (limited to 350 C) cannot function. Development of this material will enable large performance enhancements and size reductions for a wide variety of systems--such as high-frequency devices, high-power devices, microwave switching devices, and high-temperature electronics. These applications would supply more energy-efficient public electric power distribution and electric vehicles, more powerful microwave electronics for radar and communications, and better sensors and controls for cleaner-burning, more fuel-efficient jet aircraft and automobile engines. The 6H-SiC polytype is a promising wide-bandgap (Eg = 3.0 eV) semiconductor for photovoltaic applications in harsh solar environments that involve high-temperature and high-radiation conditions. The advantages of this material for this application lie in its extremely large breakdown field strength, high thermal conductivity, good electron saturation drift velocity, and stable electrical performance at temperatures as high as 600 C. This behavior makes it an attractive photovoltaic solar cell material for devices that can operate within three solar radii of the Sun.

Boron selenide semiconductor detectors for thermal neutron counting

NASA Astrophysics Data System (ADS)

Kargar, Alireza; Tower, Joshua; Cirignano, Leonard; Shah, Kanai

2013-09-01

Thermal neutron detectors in planar configuration were fabricated from B2Se3 (Boron Selenide) crystals grown at RMD Inc. All fabricated semiconductor devices were characterized for the current-voltage (I-V) characteristic and neutron counting measurement. In this study, the resistivity of crystals is reported and the collected pulse height spectra are presented for devices irradiated with the 241AmBe neutron source. Long-term stability of the B2Se3 devices for neutron detection under continuous bias and without being under continuous bias was investigated and the results are reported. The B2Se3 devices showed response to thermal neutrons of the 241AmBe source.

Packaging of solid state devices

DOEpatents

Glidden, Steven C.; Sanders, Howard D.

2006-01-03

A package for one or more solid state devices in a single module that allows for operation at high voltage, high current, or both high voltage and high current. Low thermal resistance between the solid state devices and an exterior of the package and matched coefficient of thermal expansion between the solid state devices and the materials used in packaging enables high power operation. The solid state devices are soldered between two layers of ceramic with metal traces that interconnect the devices and external contacts. This approach provides a simple method for assembling and encapsulating high power solid state devices.

Thermally modulated biomolecule transport through nanoconfined channels

NASA Astrophysics Data System (ADS)

Liu, Lei; Zhu, Lizhong

2015-04-01

In this work, a nanofluidic device containing both a feed cell and a permeation cell linked by nanopore arrays has been fabricated, which is employed to investigate thermally controlled biomolecular transporting properties through confined nanochannels. The ionic currents modulated by the translocations of goat antibody to human immunoglobulin G (IgG) or bovine serum albumin (BSA) are recorded and analyzed. The results suggest that the modulation effect decreases with the electrolyte concentration increasing, while the effects generated by IgG translocation are more significant than that generated by BSA translocation. More importantly, there is a maximum decreasing value in each modulated current curve with biomolecule concentration increasing for thermally induced intermolecular collision. Furthermore, the turning point for the maximum shifts to lower biomolecule concentrations with the system temperature rising (from 4°C to 45°C), and it is mainly determined by the temperature in the feed cell if the temperature difference exists in the two separated cells. These findings are expected to be valuable for the future design of novel sensing device based on nanopore and/or nanopore arrays.

Atomistic study of a nanometer-scale pump based on the thermal ratchet concept

NASA Astrophysics Data System (ADS)

Oyarzua, Elton; Walther, J. H.; Zambrano, Harvey

2015-11-01

In this study, a novel concept of nanoscale pump fabricated using Carbon Nanotubes (CNTs) is presented. The development of nanofluidic systems provides unprecedented possibilities for the control of biology and chemistry at the molecular level with potential applications in low energy cost devices, novel medical tools, and a new generation of sensors. CNTs offer a number of attractive features for the fabrication of fluidic nanodevices including fast flow, useful electronic and thermal properties, high mechanical strength and biocompatibility. Therefore, the transport of liquids in CNTs is now of great interest in nanofluidics. Thermophoresis is the phenomenon observed when a mixture of two or more types of motile objects experience a force induced by a thermal gradient and the different types of objects respond to it differently, inducing a motion and segregation of the objects. Using molecular dynamics simulations, we explore the possibility to design thermophoretic pumping devices fabricated of CNTs for water transport in nanoconduits. The design of the nanopumps is based on the concept of the Feynman-Smoluchowski ratchet. We aknowledge partial support from Fondecyt project 11130559 and Redoc udec.

Metal–Organic–Inorganic Nanocomposite Thermal Interface Materials with Ultralow Thermal Resistances

DOE PAGES

Yegin, Cengiz; Nagabandi, Nirup; Feng, Xuhui; ...

2017-02-27

As electronic devices get smaller and more powerful, energy density of energy storage devices increases continuously, and moving components of machinery operate at higher speeds, the need for better thermal management strategies is becoming increasingly important. The removal of heat dissipated during the operation of electronic, electrochemical, and mechanical devices is facilitated by high-performance thermal interface materials (TIMs) which are utilized to couple devices to heat sinks. Here in this paper, we report a new class of TIMs involving the chemical integration of boron nitride nanosheets (BNNS), soft organic linkers, and a copper matrix -- which are prepared by chemisorption-coupledmore » electrodeposition approach. These hybrid nanocomposites demonstrate bulk thermal conductivities ranging from 211 to 277 W/(m.K), which are very high considering their relatively low elastic modulus values on the order of 21.2 to 28.5 GPa. The synergistic combination of these properties lead to the ultra-low total thermal resistivity values in the range of 0.38 to 0.56 mm 2.K/W for a typical bondline thickness of 30-50 um, advancing the current state-of-art transformatively. Moreover, its coefficient of thermal expansion (CTE) is 11 ppm/K, forming a mediation zone with a low thermally-induced axial stress due to its close proximity to the CTE of most coupling surfaces needing thermal management.« less

Metal–Organic–Inorganic Nanocomposite Thermal Interface Materials with Ultralow Thermal Resistances

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yegin, Cengiz; Nagabandi, Nirup; Feng, Xuhui

As electronic devices get smaller and more powerful, energy density of energy storage devices increases continuously, and moving components of machinery operate at higher speeds, the need for better thermal management strategies is becoming increasingly important. The removal of heat dissipated during the operation of electronic, electrochemical, and mechanical devices is facilitated by high-performance thermal interface materials (TIMs) which are utilized to couple devices to heat sinks. Here in this paper, we report a new class of TIMs involving the chemical integration of boron nitride nanosheets (BNNS), soft organic linkers, and a copper matrix -- which are prepared by chemisorption-coupledmore » electrodeposition approach. These hybrid nanocomposites demonstrate bulk thermal conductivities ranging from 211 to 277 W/(m.K), which are very high considering their relatively low elastic modulus values on the order of 21.2 to 28.5 GPa. The synergistic combination of these properties lead to the ultra-low total thermal resistivity values in the range of 0.38 to 0.56 mm 2.K/W for a typical bondline thickness of 30-50 um, advancing the current state-of-art transformatively. Moreover, its coefficient of thermal expansion (CTE) is 11 ppm/K, forming a mediation zone with a low thermally-induced axial stress due to its close proximity to the CTE of most coupling surfaces needing thermal management.« less

Controlling Variable Emittance (MEMS) Coatings for Space Applications

NASA Technical Reports Server (NTRS)

Farrar, D.; Schneider, W.; Osiander, R.; Champion, J. L.; Darrin, A. G.; Douglas, Donya; Swanson, Ted D.

2003-01-01

Small spacecraft, including micro and nanosats, as they are envisioned for future missions, will require an alternative means to achieve thermal control due to their small power and mass budgets. One of the proposed alternatives is Variable Emittance (Vari-E) Coatings for spacecraft radiators. Space Technology-5 (ST-5) is a technology demonstration mission through NASA Goddard Space Flight Center (GSFC) that will utilize Vari-E Coatings. This mission involves a constellation of three (3) satellites in a highly elliptical orbit with a perigee altitude of approximately 200 kilometers and an apogee of approximately 38,000 kilometers. Such an environment will expose the spacecraft to a wide swing in the thermal and radiation environment of the earth's atmosphere. There are three (3) different technologies associated with this mission. The three technologies are electrophoretic, electrochromic, and Micro ElectroMechanical Systems (MEMS). The ultimate goal is to make use of Van-E coatings, in order to achieve various levels of thermal control. The focus of this paper is to highlight the Vari-E Coating MEMS instrument, with an emphasis on the Electronic Control Unit responsible for operating the MEMS device. The Test & Evaluation approach, along with the results, is specific for application on ST-5, yet the information provides a guideline for future experiments and/or thermal applications on the exterior structure of a spacecraft.

Manufacture of micro fluidic devices by laser welding using thermal transfer printing techniques

NASA Astrophysics Data System (ADS)

Klein, R.; Klein, K. F.; Tobisch, T.; Thoelken, D.; Belz, M.

2016-03-01

Micro-fluidic devices are widely used today in the areas of medical diagnostics and drug research, as well as for applications within the process, electronics and chemical industry. Microliters of fluids or single cell to cell interactions can be conveniently analyzed with such devices using fluorescence imaging, phase contrast microscopy or spectroscopic techniques. Typical micro-fluidic devices consist of a thermoplastic base component with chambers and channels covered by a hermetic fluid and gas tight sealed lid component. Both components are usually from the same or similar thermoplastic material. Different mechanical, adhesive or thermal joining processes can be used to assemble base component and lid. Today, laser beam welding shows the potential to become a novel manufacturing opportunity for midsize and large scale production of micro-fluidic devices resulting in excellent processing quality by localized heat input and low thermal stress to the device during processing. For laser welding, optical absorption of the resin and laser wavelength has to be matched for proper joining. This paper will focus on a new approach to prepare micro-fluidic channels in such devices using a thermal transfer printing process, where an optical absorbing layer absorbs the laser energy. Advantages of this process will be discussed in combination with laser welding of optical transparent micro-fluidic devices.

Solar Power Generation in Extreme Space Environments

NASA Technical Reports Server (NTRS)

Elliott, Frederick W.; Piszczor, Michael F.

2016-01-01

The exploration of space requires power for guidance, navigation, and control; instrumentation; thermal control; communications and data handling; and many subsystems and activities. Generating sufficient and reliable power in deep space through the use of solar arrays becomes even more challenging as solar intensity decreases and high radiation levels begin to degrade the performance of photovoltaic devices. The Extreme Environments Solar Power (EESP) project goal is to develop advanced photovoltaic technology to address these challenges.

Spatial and Temporal Control of Hyperthermia Using Real Time Ultrasonic Thermal Strain Imaging with Motion Compensation, Phantom Study

PubMed Central

Foiret, Josquin; Ferrara, Katherine W.

2015-01-01

Mild hyperthermia has been successfully employed to induce reversible physiological changes that can directly treat cancer and enhance local drug delivery. In this approach, temperature monitoring is essential to avoid undesirable biological effects that result from thermal damage. For thermal therapies, Magnetic Resonance Imaging (MRI) has been employed to control real-time Focused Ultrasound (FUS) therapies. However, combined ultrasound imaging and therapy systems offer the benefits of simple, low-cost devices that can be broadly applied. To facilitate such technology, ultrasound thermometry has potential to reliably monitor temperature. Control of mild hyperthermia was previously achieved using a proportional-integral-derivative (PID) controller based on thermocouple measurements. Despite accurate temporal control of heating, this method is limited by the single position at which the temperature is measured. Ultrasound thermometry techniques based on exploiting the thermal dependence of acoustic parameters (such as longitudinal velocity) can be extended to create thermal maps and allow an accurate monitoring of temperature with good spatial resolution. However, in vivo applications of this technique have not been fully developed due to the high sensitivity to tissue motion. Here, we propose a motion compensation method based on the acquisition of multiple reference frames prior to treatment. The technique was tested in the presence of 2-D and 3-D physiological-scale motion and was found to provide effective real-time temperature monitoring. PID control of mild hyperthermia in presence of motion was then tested with ultrasound thermometry as feedback and temperature was maintained within 0.3°C of the requested value. PMID:26244783

High rectifying behavior in Al/Si nanocrystal-embedded SiOxNy/p-Si heterojunctions

NASA Astrophysics Data System (ADS)

Jacques, E.; Pichon, L.; Debieu, O.; Gourbilleau, F.; Coulon, N.

2011-05-01

We examine the electrical properties of MIS devices made of Al/Si nanocrystal-SiOxNy/p-Si. The J-V characteristics of the devices present a high rectifying behavior. Temperature measurements show that the forward current is thermally activated following the thermal diffusion model of carriers. At low reverse bias, the current is governed by thermal emission amplified by the Poole-Frenkel effect of carriers from defects located at the silicon nanocrystals/SiOxNy interfaces, whereas tunnel conduction in silicon oxynitride matrix dominates at high reverse bias. The devices exhibit a rectification ratio >104 for the current measured at V = ± 1 V. Study reveals that thermal annealing in forming gas (H2/N2) improves the electrical properties of the devices due to the passivation of defects.

Thermal management in MoS{sub 2} based integrated device using near-field radiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peng, Jiebin; Zhang, Gang, E-mail: zhangg@ihpc.a-star.edu.sg; Li, Baowen

2015-09-28

Recently, wafer-scale growth of monolayer MoS{sub 2} films with spatial homogeneity is realized on SiO{sub 2} substrate. Together with the latest reported high mobility, MoS{sub 2} based integrated electronic devices are expected to be fabricated in the near future. Owing to the low lattice thermal conductivity in monolayer MoS{sub 2}, and the increased transistor density accompanied with the increased power density, heat dissipation will become a crucial issue for these integrated devices. In this letter, using the formalism of fluctuation electrodynamics, we explored the near-field radiative heat transfer from a monolayer MoS{sub 2} to graphene. We demonstrate that in resonance,more » the maximum heat transfer via near-field radiation between MoS{sub 2} and graphene can be ten times higher than the in-plane lattice thermal conduction for MoS{sub 2} sheet. Therefore, an efficient thermal management strategy for MoS{sub 2} integrated device is proposed: Graphene sheet is brought into close proximity, 10–20 nm from MoS{sub 2} device; heat energy transfer from MoS{sub 2} to graphene via near-field radiation; this amount of heat energy then be conducted to contact due to ultra-high lattice thermal conductivity of graphene. Our work sheds light for developing cooling strategy for nano devices constructing with low thermal conductivity materials.« less

Evaluation of Advanced COTS Passive Devices for Extreme Temperature Operation

NASA Technical Reports Server (NTRS)

Patterson, Richard; Hammoud, Ahmad; Dones, Keishla R.

2009-01-01

Electronic sensors and circuits are often exposed to extreme temperatures in many of NASA deep space and planetary surface exploration missions. Electronics capable of operation in harsh environments would be beneficial as they simplify overall system design, relax thermal management constraints, and meet operational requirements. For example, cryogenic operation of electronic parts will improve reliability, increase energy density, and extend the operational lifetimes of space-based electronic systems. Similarly, electronic parts that are able to withstand and operate efficiently in high temperature environments will negate the need for thermal control elements and their associated structures, thereby reducing system size and weight, enhancing its reliability, improving its efficiency, and reducing cost. Passive devices play a critical role in the design of almost all electronic circuitry. To address the needs of systems for extreme temperature operation, some of the advanced and most recently introduced commercial-off-the-shelf (COTS) passive devices, which included resistors and capacitors, were examined for operation under a wide temperature regime. The types of resistors investigated included high temperature precision film, general purpose metal oxide, and wirewound.

Microwave Dielectric Heating of Drops in Microfluidic Devices†

PubMed Central

Issadore, David; Humphry, Katherine J.; Brown, Keith A.; Sandberg, Lori; Weitz, David; Westervelt, Robert M.

2010-01-01

We present a technique to locally and rapidly heat water drops in microfluidic devices with microwave dielectric heating. Water absorbs microwave power more efficiently than polymers, glass, and oils due to its permanent molecular dipole moment that has a large dielectric loss at GHz frequencies. The relevant heat capacity of the system is a single thermally isolated picoliter drop of water and this enables very fast thermal cycling. We demonstrate microwave dielectric heating in a microfluidic device that integrates a flow-focusing drop maker, drop splitters, and metal electrodes to locally deliver microwave power from an inexpensive, commercially available 3.0 GHz source and amplifier. The temperature of the drops is measured by observing the temperature dependent fluorescence intensity of cadmium selenide nanocrystals suspended in the water drops. We demonstrate characteristic heating times as short as 15 ms to steady-state temperatures as large as 30°C above the base temperature of the microfluidic device. Many common biological and chemical applications require rapid and local control of temperature, such as PCR amplification of DNA, and can benefit from this new technique. PMID:19495453

Stoichiometric control of lead chalcogenide nanocrystal solids to enhance their electronic and optoelectronic device performance.

PubMed

Oh, Soong Ju; Berry, Nathaniel E; Choi, Ji-Hyuk; Gaulding, E Ashley; Paik, Taejong; Hong, Sung-Hoon; Murray, Christopher B; Kagan, Cherie R

2013-03-26

We investigate the effects of stoichiometric imbalance on the electronic properties of lead chalcogenide nanocrystal films by introducing excess lead (Pb) or selenium (Se) through thermal evaporation. Hall-effect and capacitance-voltage measurements show that the carrier type, concentration, and Fermi level in nanocrystal solids may be precisely controlled through their stoichiometry. By manipulating only the stoichiometry of the nanocrystal solids, we engineer the characteristics of electronic and optoelectronic devices. Lead chalcogenide nanocrystal field-effect transistors (FETs) are fabricated at room temperature to form ambipolar, unipolar n-type, and unipolar p-type semiconducting channels as-prepared and with excess Pb and Se, respectively. Introducing excess Pb forms nanocrystal FETs with electron mobilities of 10 cm(2)/(V s), which is an order of magnitude higher than previously reported in lead chalcogenide nanocrystal devices. Adding excess Se to semiconductor nanocrystal solids in PbSe Schottky solar cells enhances the power conversion efficiency.

Safety control circuit for a neutronic reactor

DOEpatents

Ellsworth, Howard C.

2004-04-27

A neutronic reactor comprising an active portion containing material fissionable by neutrons of thermal energy, means to control a neutronic chain reaction within the reactor comprising a safety device and a regulating device, a safety device including means defining a vertical channel extending into the reactor from an aperture in the upper surface of the reactor, a rod containing neutron-absorbing materials slidably disposed within the channel, means for maintaining the safety rod in a withdrawn position relative to the active portion of the reactor including means for releasing said rod on actuation thereof, a hopper mounted above the active portion of the reactor having a door disposed at the bottom of the hopper opening into the vertical channel, a plurality of bodies of neutron-absorbing materials disposed within the hopper, and means responsive to the failure of the safety rod on actuation thereof to enter the active portion of the reactor for opening the door in the hopper.

Interfacial thermal degradation in inverted organic solar cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Greenbank, William; Hirsch, Lionel; Wantz, Guillaume

2015-12-28

The efficiency of organic photovoltaic (OPV) solar cells is constantly improving; however, the lifetime of the devices still requires significant improvement if the potential of OPV is to be realised. In this study, several series of inverted OPV were fabricated and thermally aged in the dark in an inert atmosphere. It was demonstrated that all of the devices undergo short circuit current-driven degradation, which is assigned to morphology changes in the active layer. In addition, a previously unreported, open circuit voltage-driven degradation mechanism was observed that is highly material specific and interfacial in origin. This mechanism was specifically observed inmore » devices containing MoO{sub 3} and silver as hole transporting layers and electrode materials, respectively. Devices with this combination were among the worst performing devices with respect to thermal ageing. The physical origins of this mechanism were explored by Rutherford backscattering spectrometry and atomic force microscopy and an increase in roughness with thermal ageing was observed that may be partially responsible for the ageing mechanism.« less

Development of a Hard X-ray Beam Position Monitor for Insertion Device Beams at the APS

NASA Astrophysics Data System (ADS)

Decker, Glenn; Rosenbaum, Gerd; Singh, Om

2006-11-01

Long-term pointing stability requirements at the Advanced Photon Source (APS) are very stringent, at the level of 500 nanoradians peak-to-peak or better over a one-week time frame. Conventional rf beam position monitors (BPMs) close to the insertion device source points are incapable of assuring this level of stability, owing to mechanical, thermal, and electronic stability limitations. Insertion device gap-dependent systematic errors associated with the present ultraviolet photon beam position monitors similarly limit their ability to control long-term pointing stability. We report on the development of a new BPM design sensitive only to hard x-rays. Early experimental results will be presented.

Advanced technologies and devices for inhalational anesthetic drug dosing.

PubMed

Meyer, J-U; Kullik, G; Wruck, N; Kück, K; Manigel, J

2008-01-01

Technological advances in micromechanics, optical sensing, and computing have led to innovative and reliable concepts of precise dosing and sensing of modern volatile anesthetics. Mixing of saturated desflurane flow with fresh gas flow (FGF) requires differential pressure sensing between the two circuits for precise delivery. The medical gas xenon is administered most economically in a closed circuit breathing system. Sensing of xenon in the breathing system is achieved with miniaturized and unique gas detector systems. Innovative sensing principles such as thermal conductivity and sound velocity are applied. The combination of direct injection of volatile anesthetics and low-flow in a closed circuit system requires simultaneous sensing of the inhaled and exhaled gas concentrations. When anesthetic conserving devices are used for sedation with volatile anesthetics, regular gas concentration monitoring is advised. High minimal alveolar concentration (MAC) of some anesthetics and low-flow conditions bear the risk of hypoxic gas delivery. Oxygen sensing based on paramagnetic thermal transduction has become the choice when long lifetime and one-time calibration are required. Compact design of beam splitters, infrared filters, and detectors have led to multiple spectra detector systems that fit in thimble-sized housings. Response times of less than 500 ms allow systems to distinguish inhaled from exhaled gas concentrations. The compact gas detector systems are a prerequisite to provide "quantitative anesthesia" in closed circuit feedback-controlled breathing systems. Advanced anesthesia devices in closed circuit mode employ multiple feedback systems. Multiple feedbacks include controls of volume, concentrations of anesthetics, and concentration of oxygen with a corresponding safety system. In the ideal case, the feedback system delivers precisely what the patient is consuming. In this chapter, we introduce advanced technologies and device concepts for delivering inhalational anesthetic drugs. First, modern vaporizers are described with special attention to the particularities of delivering desflurane. Delivery of xenon is presented, followed by a discussion of direct injection of volatile anesthetics and of a device designed to conserve anesthetic drugs. Next, innovative sensing technologies are presented for reliable control and precise metering of the delivered volatile anesthetics. Finally, we discuss the technical challenges of automatic control in low-flow and closed circuit breathing systems in anesthesia.

Symmetric miniaturized heating system for active microelectronic devices.

PubMed

McCracken, Michael; Mayer, Michael; Jourard, Isaac; Moon, Jeong-Tak; Persic, John

2010-07-01

To qualify interconnect technologies such as microelectronic fine wire bonds for mass production of integrated circuit (IC) packages, it is necessary to perform accelerated aging tests, e.g., to age a device at an elevated temperature or to subject the device to thermal cycling and measure the decrease of interconnect quality. There are downsides to using conventional ovens for this as they are relatively large and have relatively slow temperature change rates, and if electrical connections are required between monitoring equipment and the device being heated, they must be located inside the oven and may be aged by the high temperatures. Addressing these downsides, a miniaturized heating system (minioven) is presented, which can heat individual IC packages containing the interconnects to be tested. The core of this system is a piece of copper cut from a square shaped tube with high resistance heating wire looped around it. Ceramic dual in-line packages are clamped against either open end of the core. One package contains a Pt100 temperature sensor and the other package contains the device to be aged placed in symmetry to the temperature sensor. According to the temperature detected by the Pt100, a proportional-integral-derivative controller adjusts the power supplied to the heating wire. The system maintains a dynamic temperature balance with the core hot and the two symmetric sides with electrical connections to the device under test at a cooler temperature. Only the face of the package containing the device is heated, while the socket holding it remains below 75 degrees C when the oven operates at 200 degrees C. The minioven can heat packages from room temperature up to 200 degrees C in less than 5 min and maintain this temperature at 28 W power. During long term aging, a temperature of 200 degrees C was maintained for 1120 h with negligible resistance change of the heating wires after 900 h (heating wire resistance increased 0.2% over the final 220 h). The device is also subjected to 5700 thermal cycles between 55 and 195 degrees C, demonstrating reliability under thermal cycling.

Substrate-mediated strain effect on the role of thermal heating and electric field on metal-insulator transition in vanadium dioxide nanobeams.

PubMed

Kim, Min-Woo; Jung, Wan-Gil; Hyun-Cho; Bae, Tae-Sung; Chang, Sung-Jin; Jang, Ja-Soon; Hong, Woong-Ki; Kim, Bong-Joong

2015-06-04

Single-crystalline vanadium dioxide (VO2) nanostructures have recently attracted great attention because of their single domain metal-insulator transition (MIT) nature that differs from a bulk sample. The VO2 nanostructures can also provide new opportunities to explore, understand, and ultimately engineer MIT properties for applications of novel functional devices. Importantly, the MIT properties of the VO2 nanostructures are significantly affected by stoichiometry, doping, size effect, defects, and in particular, strain. Here, we report the effect of substrate-mediated strain on the correlative role of thermal heating and electric field on the MIT in the VO2 nanobeams by altering the strength of the substrate attachment. Our study may provide helpful information on controlling the properties of VO2 nanobeam for the device applications by changing temperature and voltage with a properly engineered strain.

Substrate-mediated strain effect on the role of thermal heating and electric field on metal-insulator transition in vanadium dioxide nanobeams

PubMed Central

Kim, Min-Woo; Jung, Wan-Gil; Hyun-Cho; Bae, Tae-Sung; Chang, Sung-Jin; Jang, Ja-Soon; Hong, Woong-Ki; Kim, Bong-Joong

2015-01-01

Single-crystalline vanadium dioxide (VO2) nanostructures have recently attracted great attention because of their single domain metal-insulator transition (MIT) nature that differs from a bulk sample. The VO2 nanostructures can also provide new opportunities to explore, understand, and ultimately engineer MIT properties for applications of novel functional devices. Importantly, the MIT properties of the VO2 nanostructures are significantly affected by stoichiometry, doping, size effect, defects, and in particular, strain. Here, we report the effect of substrate-mediated strain on the correlative role of thermal heating and electric field on the MIT in the VO2 nanobeams by altering the strength of the substrate attachment. Our study may provide helpful information on controlling the properties of VO2 nanobeam for the device applications by changing temperature and voltage with a properly engineered strain. PMID:26040637

Theoretical potential for low energy consumption phase change memory utilizing electrostatically-induced structural phase transitions in 2D materials

NASA Astrophysics Data System (ADS)

Rehn, Daniel A.; Li, Yao; Pop, Eric; Reed, Evan J.

2018-01-01

Structural phase-change materials are of great importance for applications in information storage devices. Thermally driven structural phase transitions are employed in phase-change memory to achieve lower programming voltages and potentially lower energy consumption than mainstream nonvolatile memory technologies. However, the waste heat generated by such thermal mechanisms is often not optimized, and could present a limiting factor to widespread use. The potential for electrostatically driven structural phase transitions has recently been predicted and subsequently reported in some two-dimensional materials, providing an athermal mechanism to dynamically control properties of these materials in a nonvolatile fashion while achieving potentially lower energy consumption. In this work, we employ DFT-based calculations to make theoretical comparisons of the energy required to drive electrostatically-induced and thermally-induced phase transitions. Determining theoretical limits in monolayer MoTe2 and thin films of Ge2Sb2Te5, we find that the energy consumption per unit volume of the electrostatically driven phase transition in monolayer MoTe2 at room temperature is 9% of the adiabatic lower limit of the thermally driven phase transition in Ge2Sb2Te5. Furthermore, experimentally reported phase change energy consumption of Ge2Sb2Te5 is 100-10,000 times larger than the adiabatic lower limit due to waste heat flow out of the material, leaving the possibility for energy consumption in monolayer MoTe2-based devices to be orders of magnitude smaller than Ge2Sb2Te5-based devices.

Wafer-level vacuum/hermetic packaging technologies for MEMS

NASA Astrophysics Data System (ADS)

Lee, Sang-Hyun; Mitchell, Jay; Welch, Warren; Lee, Sangwoo; Najafi, Khalil

2010-02-01

An overview of wafer-level packaging technologies developed at the University of Michigan is presented. Two sets of packaging technologies are discussed: (i) a low temperature wafer-level packaging processes for vacuum/hermeticity sealing, and (ii) an environmentally resistant packaging (ERP) technology for thermal and mechanical control as well as vacuum packaging. The low temperature wafer-level encapsulation processes are implemented using solder bond rings which are first patterned on a cap wafer and then mated with a device wafer in order to encircle and encapsulate the device at temperatures ranging from 200 to 390 °C. Vacuum levels below 10 mTorr were achieved with yields in an optimized process of better than 90%. Pressures were monitored for more than 4 years yielding important information on reliability and process control. The ERP adopts an environment isolation platform in the packaging substrate. The isolation platform is designed to provide low power oven-control, vibration isolation and shock protection. It involves batch flip-chip assembly of a MEMS device onto the isolation platform wafer. The MEMS device and isolation structure are encapsulated at the wafer-level by another substrate with vertical feedthroughs for vacuum/hermetic sealing and electrical signal connections. This technology was developed for high performance gyroscopes, but can be applied to any type of MEMS device.

Engineering highly organized and aligned single walled carbon nanotube networks for electronic device applications: Interconnects, chemical sensor, and optoelectronics

NASA Astrophysics Data System (ADS)

Kim, Young Lae

For 20 years, single walled carbon nanotubes (SWNTs) have been studied actively due to their unique one-dimensional nanostructure and superior electrical, thermal, and mechanical properties. For these reasons, they offer the potential to serve as building blocks for future electronic devices such as field effect transistors (FETs), electromechanical devices, and various sensors. In order to realize these applications, it is crucial to develop a simple, scalable, and reliable nanomanufacturing process that controllably places aligned SWNTs in desired locations, orientations, and dimensions. Also electronic properties (semiconducting/metallic) of SWNTs and their organized networks must be controlled for the desired performance of devices and systems. These fundamental challenges are significantly limiting the use of SWNTs for future electronic device applications. Here, we demonstrate a strategy to fabricate highly controlled micro/nanoscale SWNT network structures and present the related assembly mechanism to engineer the SWNT network topology and its electrical transport properties. A method designed to evaluate the electrical reliability of such nano- and microscale SWNT networks is also presented. Moreover, we develop and investigate a robust SWNT based multifunctional selective chemical sensor and a range of multifunctional optoelectronic switches, photo-transistors, optoelectronic logic gates and complex optoelectronic digital circuits.

Impact of vacancy ordering on thermal transport in crystalline phase-change materials.

PubMed

Siegert, K S; Lange, F R L; Sittner, E R; Volker, H; Schlockermann, C; Siegrist, T; Wuttig, M

2015-01-01

Controlling thermal transport in solids is of paramount importance for many applications. Often thermal management is crucial for a device's performance, as it affects both reliability and power consumption. A number of intricate concepts have been developed to address this challenge, such as diamond-like coatings to enhance the thermal conductivity or low symmetry complex super-structures to reduce it. Here, a different approach is pursued, where we explore the potential of solids with a high yet controllable degree of disorder. Recently, it has been demonstrated that an unconventionally high degree of structural disorder characterizes a number of crystalline phase-change materials (PCMs). This disorder strongly impacts electronic transport and even leads to disorder induced localization (Anderson localization). This raises the question how thermal transport is affected by such conditions. Here thermal transport in highly disordered crystalline Ge-Sb-Te (GST) based PCMs is investigated. Glass-like thermal properties are observed for several crystalline PCMs, which are attributed to strong scattering by disordered point defects. A systematic study of different compounds along the pseudo-binary line between GeTe and Sb2Te3 reveals that disordered vacancies act as point defects responsible for pronounced phonon scattering. Annealing causes a gradual ordering of the vacancies and leads to a more 'crystal-like' thermal conductivity. While both vibrational and electronic degrees of freedom are affected by disorder, the consequences differ for different stoichiometries. This opens up a pathway to tune electrical and thermal transport by controlling the degree of disorder. Materials with tailored transport properties may not only help to improve power efficiency and scaling in upcoming phase-change memories but are also of fundamental interest in the field of thermoelectric materials.

Impact of vacancy ordering on thermal transport in crystalline phase-change materials

NASA Astrophysics Data System (ADS)

Siegert, K. S.; Lange, F. R. L.; Sittner, E. R.; Volker, H.; Schlockermann, C.; Siegrist, T.; Wuttig, M.

2015-01-01

Controlling thermal transport in solids is of paramount importance for many applications. Often thermal management is crucial for a device's performance, as it affects both reliability and power consumption. A number of intricate concepts have been developed to address this challenge, such as diamond-like coatings to enhance the thermal conductivity or low symmetry complex super-structures to reduce it. Here, a different approach is pursued, where we explore the potential of solids with a high yet controllable degree of disorder. Recently, it has been demonstrated that an unconventionally high degree of structural disorder characterizes a number of crystalline phase-change materials (PCMs). This disorder strongly impacts electronic transport and even leads to disorder induced localization (Anderson localization). This raises the question how thermal transport is affected by such conditions. Here thermal transport in highly disordered crystalline Ge-Sb-Te (GST) based PCMs is investigated. Glass-like thermal properties are observed for several crystalline PCMs, which are attributed to strong scattering by disordered point defects. A systematic study of different compounds along the pseudo-binary line between GeTe and Sb2Te3 reveals that disordered vacancies act as point defects responsible for pronounced phonon scattering. Annealing causes a gradual ordering of the vacancies and leads to a more ‘crystal-like’ thermal conductivity. While both vibrational and electronic degrees of freedom are affected by disorder, the consequences differ for different stoichiometries. This opens up a pathway to tune electrical and thermal transport by controlling the degree of disorder. Materials with tailored transport properties may not only help to improve power efficiency and scaling in upcoming phase-change memories but are also of fundamental interest in the field of thermoelectric materials.

Personal cooling air filtering device

DOEpatents

Klett, James [Knoxville, TN; Conway, Bret [Denver, NC

2002-08-13

A temperature modification system for modifying the temperature of fluids includes at least one thermally conductive carbon foam element, the carbon foam element having at least one flow channel for the passage of fluids. At least one temperature modification device is provided, the temperature modification device thermally connected to the carbon foam element and adapted to modify the temperature of the carbon foam to modify the temperature of fluids flowing through the flow channels. Thermoelectric and/or thermoionic elements can preferably be used as the temperature modification device. A method for the reversible temperature modification of fluids includes the steps of providing a temperature modification system including at least one thermally conductive carbon foam element having flow channels and at least one temperature modification device, and flowing a fluid through the flow channels.

Characterizing Thermal Properties of Melting Te Semiconductor: Thermal Diffusivity Measurements and Simulation

NASA Technical Reports Server (NTRS)

Zhu, Shen; Li, C.; Su, Ching-Hua; Lin, B.; Ben, H.; Scripa, R. N.; Lehoczky, S. L.; Curreri, Peter A. (Technical Monitor)

2002-01-01

Tellurium is an element for many II-VI and I-III-VI(sub 2) compounds that are useful materials for fabricating many devices. In the melt growth techniques, the thermal properties of the molten phase are important parameter for controlling growth process to improve semiconducting crystal quality. In this study, thermal diffusivity of molten tellurium has been measured by a laser flash method in the temperature range from 500 C to 900 C. A pulsed laser with 1064 nm wavelength is focused on one side of the measured sample. The thermal diffusivity can be estimated from the temperature transient at the other side of the sample. A numerical simulation based on the thermal transport process has been also performed. By numerically fitting the experimental results, both the thermal conductivity and heat capacity can be derived. A relaxation phenomenon, which shows a slow drift of the measured thermal conductivity toward the equilibrium value after cooling of the sample, was observed for the first time. The error analysis and the comparison of the results to published data measured by other techniques will be discussed.

Evaluation of Silicon-on-Insulator HTOP-01 Operational Amplifier for Wide Temperature Operation

NASA Technical Reports Server (NTRS)

Patterson, Richard; Hammoud, Ahmad; Elbuluk, Malik

2008-01-01

Electronics capable of operation under extreme temperatures are required in many of NASA space exploration missions. Aerospace and military applications, as well as some terrestrial industries constitute environments where electronic systems are anticipated to be exposed to extreme temperatures and wide-range thermal swings. Electronics that are able to withstand and operate efficiently in such harsh environments would simplify, if not eliminate, traditional thermal control elements and their associated structures for proper ambient operation. As a result, overall system mass would be reduced, design would be simplified, and reliability would be improved. Electronic parts that are built utilizing silicon-on-insulator (SOI) technology are known to offer better radiation-tolerance compared to their conventional silicon counterparts, provide faster switching, and consume less power. They also exhibit reduced leakage current and, thus, they are often tailored for high temperature operation. These attributes make SOI-based devices suitable for use in harsh environments where extreme temperatures and wide thermal swings are anticipated. A new operational amplifier, based on silicon-on-insulator technology and geared for high temperature well-logging applications, was recently introduced by Honeywell Corporation. This HTOP-01 dual precision operational amplifier is a low power device, operates on a single supply, and has an internal oscillator and an external clocking option [1]. It is rated for operation from -55 C to +225 C with a maximum output current capability of 50 mA. The amplifier chip is designed as a 14-pin, hermetically-sealed device in a ceramic package. Table I shows some of the device manufacturer s specifications.

Making Record-efficiency SnS Solar Cells by Thermal Evaporation and Atomic Layer Deposition

PubMed Central

Jaramillo, Rafael; Steinmann, Vera; Yang, Chuanxi; Hartman, Katy; Chakraborty, Rupak; Poindexter, Jeremy R.; Castillo, Mariela Lizet; Gordon, Roy; Buonassisi, Tonio

2015-01-01

Tin sulfide (SnS) is a candidate absorber material for Earth-abundant, non-toxic solar cells. SnS offers easy phase control and rapid growth by congruent thermal evaporation, and it absorbs visible light strongly. However, for a long time the record power conversion efficiency of SnS solar cells remained below 2%. Recently we demonstrated new certified record efficiencies of 4.36% using SnS deposited by atomic layer deposition, and 3.88% using thermal evaporation. Here the fabrication procedure for these record solar cells is described, and the statistical distribution of the fabrication process is reported. The standard deviation of efficiency measured on a single substrate is typically over 0.5%. All steps including substrate selection and cleaning, Mo sputtering for the rear contact (cathode), SnS deposition, annealing, surface passivation, Zn(O,S) buffer layer selection and deposition, transparent conductor (anode) deposition, and metallization are described. On each substrate we fabricate 11 individual devices, each with active area 0.25 cm2. Further, a system for high throughput measurements of current-voltage curves under simulated solar light, and external quantum efficiency measurement with variable light bias is described. With this system we are able to measure full data sets on all 11 devices in an automated manner and in minimal time. These results illustrate the value of studying large sample sets, rather than focusing narrowly on the highest performing devices. Large data sets help us to distinguish and remedy individual loss mechanisms affecting our devices. PMID:26067454

Use of a Frequency Divider to Evaluate an SOI NAND Gate Device, Type CHT-7400, for Wide Temperature Applications

NASA Technical Reports Server (NTRS)

Patterson, Richard L.; Hammoud, Ahmad

2010-01-01

Frequency dividers constitute essential elements in designing phase-locked loop circuits and microwave systems. In addition, they are used in providing required clocking signals to microprocessors and can be utilized as digital counters. In some applications, particularly space missions, electronics are often exposed to extreme temperature conditions. Therefore, it is required that circuits designed for such applications incorporate electronic parts and devices that can tolerate and operate efficiently in harsh temperature environments. While present electronic circuits employ COTS (commercial-off- the-shelf) parts that necessitate and are supported with some form of thermal control systems to maintain adequate temperature for proper operation, it is highly desirable and beneficial if the thermal conditioning elements are eliminated. Amongst these benefits are: simpler system design, reduced weight and size, improved reliability, simpler maintenance, and reduced cost. Devices based on silicon-on-insulator (SOI) technology, which utilizes the addition of an insulation layer in the device structure to reduce leakage currents and to minimize parasitic junctions, are well suited for high temperatures due to reduced internal heating as compared to the conventional silicon devices, and less power consumption. In addition, SOI electronic integrated circuits display good tolerance to radiation by virtue of introducing barriers or lengthening the path for penetrating particles and/or providing a region for trapping incident ionization. The benefits of these parts make them suitable for use in deep space and planetary exploration missions where extreme temperatures and radiation are encountered. Although designed for high temperatures, very little data exist on the operation of SOI devices and circuits at cryogenic temperatures. In this work, the performance of a divide-by-two frequency divider circuit built using COTS SOI logic gates was evaluated over a wide temperature range and thermal cycling to determine suitability for use in space exploration missions and terrestrial fields under extreme temperature conditions.

Microfabricated thermoelectric power-generation devices

NASA Technical Reports Server (NTRS)

Fleurial, Jean-Pierre (Inventor); Phillips, Wayne (Inventor); Borshchevsky, Alex (Inventor); Kolawa, Elizabeth A. (Inventor); Ryan, Margaret A. (Inventor); Caillat, Thierry (Inventor); Mueller, Peter (Inventor); Snyder, G. Jeffrey (Inventor); Kascich, Thorsten (Inventor)

2002-01-01

A device for generating power to run an electronic component. The device includes a heat-conducting substrate (composed, e.g., of diamond or another high thermal conductivity material) disposed in thermal contact with a high temperature region. During operation, heat flows from the high temperature region into the heat-conducting substrate, from which the heat flows into the electrical power generator. A thermoelectric material (e.g., a BiTe alloy-based film or other thermoelectric material) is placed in thermal contact with the heat-conducting substrate. A low temperature region is located on the side of the thermoelectric material opposite that of the high temperature region. The thermal gradient generates electrical power and drives an electrical component.

Microfabricated thermoelectric power-generation devices

NASA Technical Reports Server (NTRS)

Fleurial, Jean-Pierre (Inventor); Ryan, Margaret A. (Inventor); Borshchevsky, Alex (Inventor); Phillips, Wayne (Inventor); Kolawa, Elizabeth A. (Inventor); Snyder, G. Jeffrey (Inventor); Caillat, Thierry (Inventor); Kascich, Thorsten (Inventor); Mueller, Peter (Inventor)

2004-01-01

A device for generating power to run an electronic component. The device includes a heat-conducting substrate (composed, e.g., of diamond or another high thermal conductivity material) disposed in thermal contact with a high temperature region. During operation, heat flows from the high temperature region into the heat-conducting substrate, from which the heat flows into the electrical power generator. A thermoelectric material (e.g., a BiTe alloy-based film or other thermoelectric material) is placed in thermal contact with the heat-conducting substrate. A low temperature region is located on the side of the thermoelectric material opposite that of the high temperature region. The thermal gradient generates electrical power and drives an electrical component.

Self-Healing Thermal Annealing: Surface Morphological Restructuring Control of GaN Nanorods

DOE Office of Scientific and Technical Information (OSTI.GOV)

Conroy, Michele; Li, Haoning; Zubialevich, Vitaly Z.

With advances in nanolithography and dry etching, top-down methods of nanostructuring have become a widely used tool for improving the efficiency of optoelectronics. These nano dimensions can offer various benefits to the device performance in terms of light extraction and efficiency, but often at the expense of emission color quality. Broadening of the target emission peak and unwanted yellow luminescence are characteristic defect-related effects due to the ion beam etching damage, particularly for III–N based materials. In this article we focus on GaN based nanorods, showing that through thermal annealing the surface roughness and deformities of the crystal structure canmore » be “self-healed”. Correlative electron microscopy and atomic force microscopy show the change from spherical nanorods to faceted hexagonal structures, revealing the temperature-dependent surface morphology faceting evolution. The faceted nanorods were shown to be strain- and defect-free by cathodoluminescence hyperspectral imaging, micro-Raman, and transmission electron microscopy (TEM). In-situ TEM thermal annealing experiments allowed for real time observation of dislocation movements and surface restructuring observed in ex-situ annealing TEM sampling. This thermal annealing investigation gives new insight into the redistribution path of GaN material and dislocation movement post growth, allowing for improved understanding and in turn advances in optoelectronic device processing of compound semiconductors.« less

Effects of low Earth orbit environment on the Long Duration Exposure Facility thermal control coatings

NASA Technical Reports Server (NTRS)

Sampair, Thomas R.; Berrios, William M.

1992-01-01

One of the benefits of the Long Duration Exposure Facility (LDEF) was the opportunity to study the before and after effects of low earth orbit space environment on the spacecraft thermal control coatings. Since the LDEF's thermal control was totally passive by design, the selection of the external surface absorptivity to emissivity ratio (alpha/epsilon) and the ability for the coating to retain the alpha/epsilon over time was an important consideration in the thermal design of the LDEF. The primary surface coating chosen for the LDEF structure was clear chromic anodized aluminum with an average design alpha/epsilon of 0.32/0.16. External surface absorptivity (alpha) and emissivity (epsilon) were measured on all intercostals, longerons, tray mounting flanges, thermal control panels, and a limited number of experiment surface coatings after the experiment trays were removed from the LDEF structure. All surface alpha/epsilon measurements were made using portable hand held infrared and solar spectrum reflectometers. The absorptivity measurements were taken with a Devices and Services SSR-ER version 5.0 solar spectra reflectometer which has a stated uncertainty of +/- 0.01, and all normal emissivity measurements were made using the Gier Dunkle DB-100 infrared reflectometer also with a stated uncertainty of +/- 0.01. Both instruments were calibrated in the laboratory by LaRC instrumentation personnel before being used in the field at KSC. A combined total of 733 measurements were taken on the anodized aluminum hardware which included the structure (intercostals, longerons, and center ring), earth and space end thermal control panels, and experiment tray mounting flanges. The facility thermal control coatings measured in this survey cover 33 percent of the total exposed LDEF surface area. To correlate low earth orbit environmental effects on the anodized coatings, measurements were taken in both exposed and unexposed surfaces and compared to quality assurance (QA) measurements taken on the new surfaces at the time of hardware fabrication in 1978. The results of investigation are presented.

Thermal ink-jet device using single-chip silicon microchannels

NASA Astrophysics Data System (ADS)

Wuu, DongSing; Cheng, Chen-Yue; Horng, RayHua; Chan, G. C.; Chiu, Sao-Ling; Wu, Yi-Yung

1998-06-01

We present a new method to fabricate silicon microfluidic channels by through-hole etching with subsequent planarization. The method is based on etching out the deep grooves through a perforated silicon carbide membrane, followed by sealing the membrane with plasma-enhanced chemical vapor deposition (PECVD). Low-pressure-chemical-vapor- deposited (LPCVD) polysilicon was used as a sacrificial layer to define the channel structure and only one etching step is required. This permits the realization of planarization after a very deep etching step in silicon and offers the possibility for film deposition, resist spinning and film patterning across deep grooves. The process technology was demonstrated on the fabrication of a monolithic silicon microchannel structure for thermal inkjet printing. The Ta-Al heater arrays are integrated on the top of each microchannel, which connect to a common on-chip front-end ink reservoir. The fabrication of this device requires six masks and no active nozzle-to-chip alignment. Moreover, the present micromachining process is compatible with the addition of on-chip circuitry for multiplexing the heater control signals. Heat transfer efficiency to the ink is enhanced by the high thermal conductivity of the silicon carbide in the channel ceiling, while the bulk silicon maintains high interchannel isolation. The fabricated inkjet devices show the droplet sizes of 20 - 50 micrometer in diameter with various channel dimensions and stable ejection of ink droplets more than 1 million.

Micro/nanostructured surface modification using femtosecond laser pulses on minimally invasive electrosurgical devices.

PubMed

Lin, Chia-Cheng; Lin, Hao-Jan; Lin, Yun-Ho; Sugiatno, Erwan; Ruslin, Muhammad; Su, Chen-Yao; Ou, Keng-Liang; Cheng, Han-Yi

2017-05-01

The purpose of the present study was to examine thermal damage and a sticking problem in the tissue after the use of a minimally invasive electrosurgical device with a nanostructured surface treatment that uses a femtosecond laser pulse (FLP) technique. To safely use an electrosurgical device in clinical surgery, it is important to decrease thermal damage to surrounding tissues. The surface characteristics and morphology of the FLP layer were evaluated using optical microscopy, scanning electron microscopy, and transmission electron microscopy; element analysis was performed using energy-dispersive X-ray spectroscopy, grazing incidence X-ray diffraction, and X-ray photoelectron spectroscopy. In the animal model, monopolar electrosurgical devices were used to create lesions in the legs of 30 adult rats. Animals were sacrificed for investigations at 0, 3, 7, 14, and 28 days postoperatively. Results indicated that the thermal damage and sticking situations were reduced significantly when a minimally invasive electrosurgical instrument with an FLP layer was used. Temperatures decreased while film thickness increased. Thermographic data revealed that surgical temperatures in an animal model were significantly lower in the FLP electrosurgical device compared with that in the untreated one. Furthermore, the FLP device created a relatively small area of thermal damage. As already mentioned, the biomedical nanostructured layer reduced thermal damage and promoted the antisticking property with the use of a minimally invasive electrosurgical device. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 865-873, 2017. © 2016 Wiley Periodicals, Inc.

Elastic and thermal expansion asymmetry in dense molecular materials.

PubMed

Burg, Joseph A; Dauskardt, Reinhold H

2016-09-01

The elastic modulus and coefficient of thermal expansion are fundamental properties of elastically stiff molecular materials and are assumed to be the same (symmetric) under both tension and compression loading. We show that molecular materials can have a marked asymmetric elastic modulus and coefficient of thermal expansion that are inherently related to terminal chemical groups that limit molecular network connectivity. In compression, terminal groups sterically interact to stiffen the network, whereas in tension they interact less and disconnect the network. The existence of asymmetric elastic and thermal expansion behaviour has fundamental implications for computational approaches to molecular materials modelling and practical implications on the thermomechanical strains and associated elastic stresses. We develop a design space to control the degree of elastic asymmetry in molecular materials, a vital step towards understanding their integration into device technologies.

Numerical Study on the Thermal Stress and its Formation Mechanism of a Thermoelectric Device

NASA Astrophysics Data System (ADS)

Pan, Tao; Gong, Tingrui; Yang, Wei; Wu, Yongjia

2018-06-01

The strong thermo-mechanical stress is one of the most critical failure mechanisms that affect the durability of thermoelectric devices. In this study, numerical simulations on the formation mechanism of the maximum thermal stress inside the thermoelectric device have been performed by using finite element method. The influences of the material properties and the thermal radiation on the thermal stress have been examined. The results indicate that the maximum thermal stress was located at the contact position between the two materials and occurred due to differential thermal expansions and displacement constraints of the materials. The difference in the calculated thermal stress value between the constant and the variable material properties was between 3% and 4%. At a heat flux of 1 W·cm-2 and an emissivity of 0.5, the influence of the radiation heat transfer on the thermal stress was only about 5%; however, when the heat flux was 20 W·cm-2 and the emissivity was 0.7, the influence of the radiation heat transfer was more than 30%.

Fast and high resolution thermal detector based on an aluminum nitride piezoelectric microelectromechanical resonator with an integrated suspended heat absorbing element

NASA Astrophysics Data System (ADS)

Hui, Yu; Rinaldi, Matteo

2013-03-01

This letter presents a miniaturized, fast, and high resolution thermal detector, in which a heat absorbing element and a temperature sensitive microelectromechanical system (MEMS) resonator are perfectly overlapped but separated by a microscale air gap. This unique design guarantees efficient and fast (˜10s μs) heat transfer from the absorbing element to the temperature sensitive device and enables high resolution thermal power detection (˜nW), thanks to the low noise performance of the high quality factor (Q = 2305) MEMS resonant thermal detector. A device prototype was fabricated, and its detection capabilities were experimentally characterized. A thermal power as low as 150 nW was experimentally measured, and a noise equivalent power of 6.5 nW/Hz1/2 was extracted. A device thermal time constant of only 350 μs was measured (smallest ever reported for MEMS resonant thermal detectors), indicating the great potential of the proposed technology for the implementation of ultra-fast and high resolution un-cooled resonant thermal detectors.

40 CFR 63.6000 - How do I conduct tests and procedures for puncture sealant application affected sources?

Code of Federal Regulations, 2011 CFR

2011-07-01

... oxidizer, monitor the firebox secondary chamber temperature. (ii) If you use a carbon adsorber, monitor the total regeneration stream mass or volumetric flow for each regeneration cycle, and the carbon bed... control device used other than a thermal oxidizer or a regenerative carbon adsorber, install and operate a...

40 CFR 63.6000 - How do I conduct tests and procedures for puncture sealant application affected sources?

Code of Federal Regulations, 2010 CFR

2010-07-01

... oxidizer, monitor the firebox secondary chamber temperature. (ii) If you use a carbon adsorber, monitor the total regeneration stream mass or volumetric flow for each regeneration cycle, and the carbon bed... control device used other than a thermal oxidizer or a regenerative carbon adsorber, install and operate a...

On-demand acoustic droplet splitting and steering in a disposable microfluidic chip.

PubMed

Park, Jinsoo; Jung, Jin Ho; Park, Kwangseok; Destgeer, Ghulam; Ahmed, Husnain; Ahmad, Raheel; Sung, Hyung Jin

2018-01-30

On-chip droplet splitting is one of the fundamental droplet-based microfluidic unit operations to control droplet volume after production and increase operational capability, flexibility, and throughput. Various droplet splitting methods have been proposed, and among them the acoustic droplet splitting method is promising because of its label-free operation without any physical or thermal damage to droplets. Previous acoustic droplet splitting methods faced several limitations: first, they employed a cross-type acoustofluidic device that precluded multichannel droplet splitting; second, they required irreversible bonding between a piezoelectric substrate and a microfluidic chip, such that the fluidic chip was not replaceable. Here, we present a parallel-type acoustofluidic device with a disposable microfluidic chip to address the limitations of previous acoustic droplet splitting devices. In the proposed device, an acoustic field is applied in the direction opposite to the flow direction to achieve multichannel droplet splitting and steering. A disposable polydimethylsiloxane microfluidic chip is employed in the developed device, thereby removing the need for permanent bonding and improving the flexibility of the droplet microfluidic device. We experimentally demonstrated on-demand acoustic droplet bi-splitting and steering with precise control over the droplet splitting ratio, and we investigated the underlying physical mechanisms of droplet splitting and steering based on Laplace pressure and ray acoustics analyses, respectively. We also demonstrated droplet tri-splitting to prove the feasibility of multichannel droplet splitting. The proposed on-demand acoustic droplet splitting device enables on-chip droplet volume control in various droplet-based microfluidic applications.

Assessment of penetrating thermal tissue damage/spread associated with PhotonBlade™, Valleylab™ Pencil, Valleylab™ EDGE™ Coated Pencil, PlasmaBlade® 3.0S and PlasmaBlade® 4.0 for intraoperative tissue dissection using the fresh extirpated porcine muscle model

NASA Astrophysics Data System (ADS)

Bennett, Haydon E.; Taylor, Scott D.; Fugett, James H.; Shrout, Joshua L.; Davison, Paul O.; Ryan, S. Eric; Coad, James E.

2017-02-01

Penetrating thermal tissue damage/spread is an important aspect of many electrosurgical devices and correlates with effective tissue cutting, hemostasis, preservation of adjacent critical structures and tissue healing. This study compared the thermal damage/spread associated with the PhotonBlade, Valleylab Pencil, Valleylab EDGE Coated Pencil, PlasmaBlade 3.0S and PlasmaBlade 4.0, when performing a single pass dynamic tissue cut in fresh extirpated porcine longissimus muscle. These devices were used in a fashion that emulated their use in the clinical setting. Each device's thermal damage/spread, at Minimum, Median and Maximum power input settings, was assessed with nitroblue tetrazolium viability staining in the WVU Pathology Laboratory for Translational Medicine. The thermal damage/spread associated with the PhotonBlade was compared with the other devices tested based on the individual treatment results (n=179 cuts combined). In summary, the PhotonBlade overall demonstrated the least penetrating thermal tissue damage/spread, followed by the PlasmaBlade 4.0, then Valleylab Pencil and PlasmaBlade 3.0S and then Valleylab EDGE Coated Pencil in order of increasing thermal damage/spread depths.

Phloem-sap-dynamics sensor device for monitoring photosynthates transportation in plant shoots

NASA Astrophysics Data System (ADS)

Yano, Yuya; Ono, Akihito; Terao, Kyohei; Suzuki, Takaaki; Takao, Hidekuni; Kobayashi, Tsuyoshi; Kataoka, Ikuo; Shimokawa, Fusao

2018-06-01

We propose a microscale phloem-sap-dynamics sensor device to obtain the index of an internal plant condition regarding the transportation of primary photosynthates in phloem, which is an essential indicator of stable crop production under controlled-growth environments. In detail, we integrated a conventional Granier sensor with a thermal-flow sensor and devised an improved sensor device to quantify such index, including the information on velocity and direction of the phloem-sap flow using the microelectromechanical systems (MEMS) technology. The experimental results showed that although the proposed sensor device was approximately only 1/10 the size of the conventional Granier sensor, it could generate an output nearly equal to that of the conventional sensor. Furthermore, experiments using mimicked plants demonstrated that the proposed device could measure minute flow velocities in the range of 0–200 µm/s, which are generally known as the phloem-sap flow velocity, and simultaneously detect the flow direction.

Wireless Displacement Sensing of Micromachined Spiral-Coil Actuator Using Resonant Frequency Tracking

PubMed Central

Ali, Mohamed Sultan Mohamed; AbuZaiter, Alaa; Schlosser, Colin; Bycraft, Brad; Takahata, Kenichi

2014-01-01

This paper reports a method that enables real-time displacement monitoring and control of micromachined resonant-type actuators using wireless radiofrequency (RF). The method is applied to an out-of-plane, spiral-coil microactuator based on shape-memory-alloy (SMA). The SMA spiral coil forms an inductor-capacitor resonant circuit that is excited using external RF magnetic fields to thermally actuate the coil. The actuation causes a shift in the circuit's resonance as the coil is displaced vertically, which is wirelessly monitored through an external antenna to track the displacements. Controlled actuation and displacement monitoring using the developed method is demonstrated with the microfabricated device. The device exhibits a frequency sensitivity to displacement of 10 kHz/μm or more for a full out-of-plane travel range of 466 μm and an average actuation velocity of up to 155 μm/s. The method described permits the actuator to have a self-sensing function that is passively operated, thereby eliminating the need for separate sensors and batteries on the device, thus realizing precise control while attaining a high level of miniaturization in the device. PMID:25014100

Application of optical character recognition in thermal image processing

NASA Astrophysics Data System (ADS)

Chan, W. T.; Sim, K. S.; Tso, C. P.

2011-07-01

This paper presents the results of a study on the reliability of the thermal imager compared to other devices that are used in preventive maintenance. Several case studies are used to facilitate the comparisons. When any device is found to perform unsatisfactorily where there is a suspected fault, its short-fall is determined so that the other devices may compensate, if possible. This study discovered that the thermal imager is not suitable or efficient enough for systems that happen to have little contrast in temperature between its parts or small but important parts that have their heat signatures obscured by those from other parts. The thermal imager is also found to be useful for preliminary examinations of certain systems, after which other more economical devices are suitable substitutes for further examinations. The findings of this research will be useful to the design and planning of preventive maintenance routines for industrial benefits.

Thermal Peak Management Using Organic Phase Change Materials for Latent Heat Storage in Electronic Applications

PubMed Central

Maxa, Jacob; Novikov, Andrej; Nowottnick, Mathias

2017-01-01

Modern high power electronics devices consists of a large amount of integrated circuits for switching and supply applications. Beside the benefits, the technology exhibits the problem of an ever increasing power density. Nowadays, heat sinks that are directly mounted on a device, are used to reduce the on-chip temperature and dissipate the thermal energy to the environment. This paper presents a concept of a composite coating for electronic components on printed circuit boards or electronic assemblies that is able to buffer a certain amount of thermal energy, dissipated from a device. The idea is to suppress temperature peaks in electronic components during load peaks or electronic shorts, which otherwise could damage or destroy the device, by using a phase change material to buffer the thermal energy. The phase change material coating could be directly applied on the chip package or the PCB using different mechanical retaining jigs.

Integrated-optics heralded controlled-NOT gate for polarization-encoded qubits

NASA Astrophysics Data System (ADS)

Zeuner, Jonas; Sharma, Aditya N.; Tillmann, Max; Heilmann, René; Gräfe, Markus; Moqanaki, Amir; Szameit, Alexander; Walther, Philip

2018-03-01

Recent progress in integrated-optics technology has made photonics a promising platform for quantum networks and quantum computation protocols. Integrated optical circuits are characterized by small device footprints and unrivalled intrinsic interferometric stability. Here, we take advantage of femtosecond-laser-written waveguides' ability to process polarization-encoded qubits and present an implementation of a heralded controlled-NOT gate on chip. We evaluate the gate performance in the computational basis and a superposition basis, showing that the gate can create polarization entanglement between two photons. Transmission through the integrated device is optimized using thermally expanded core fibers and adiabatically reduced mode-field diameters at the waveguide facets. This demonstration underlines the feasibility of integrated quantum gates for all-optical quantum networks and quantum repeaters.

Tunable surface plasmon devices

DOEpatents

Shaner, Eric A [Rio Rancho, NM; Wasserman, Daniel [Lowell, MA

2011-08-30

A tunable extraordinary optical transmission (EOT) device wherein the tunability derives from controlled variation of the dielectric constant of a semiconducting material (semiconductor) in evanescent-field contact with a metallic array of sub-wavelength apertures. The surface plasmon resonance wavelength can be changed by changing the dielectric constant of the dielectric material. In embodiments of this invention, the dielectric material is a semiconducting material. The dielectric constant of the semiconducting material in the metal/semiconductor interfacial region is controllably adjusted by adjusting one or more of the semiconductor plasma frequency, the concentration and effective mass of free carriers, and the background high-frequency dielectric constant in the interfacial region. Thermal heating and/or voltage-gated carrier-concentration changes may be used to variably adjust the value of the semiconductor dielectric constant.

IMAPS Device Packaging Conference 2017 - Engineered Micro Systems & Devices Track

NASA Technical Reports Server (NTRS)

Varnavas, Kosta

2017-01-01

NASA field center Marshall Space Flight Center (Huntsville, AL), has invested in advanced wireless sensor technology development. Developments for a wireless microcontroller back-end were primarily focused on the commercial Synapse Wireless family of devices. These devices have many useful features for NASA applications, good characteristics and the ability to be programmed Over-The-Air (OTA). The effort has focused on two widely used sensor types, mechanical strain gauges and thermal sensors. Mechanical strain gauges are used extensively in NASA structural testing and even on vehicle instrumentation systems. Additionally, thermal monitoring with many types of sensors is extensively used. These thermal sensors include thermocouples of all types, resistive temperature devices (RTDs), diodes and other thermal sensor types. The wireless thermal board will accommodate all of these types of sensor inputs to an analog front end. The analog front end on each of the sensors interfaces to the Synapse wireless microcontroller, based on the Atmel Atmega128 device. Once the analog sensor output data is digitized by the onboard analog to digital converter (A/D), the data is available for analysis, computation or transmission. Various hardware features allow custom embedded software to manage battery power to enhance battery life. This technology development fits nicely into using numerous additional sensor front ends, including some of the low-cost printed circuit board capacitive moisture content sensors currently being developed at Auburn University.

Thermally driven microfluidic pumping via reversible shape memory polymers

NASA Astrophysics Data System (ADS)

Robertson, J. M.; Rodriguez, R. X.; Holmes, L. R., Jr.; Mather, P. T.; Wetzel, E. D.

2016-08-01

The need exists for autonomous microfluidic pumping systems that utilize environmental cues to transport fluid within a network of channels for such purposes as heat distribution, self-healing, or optical reconfiguration. Here, we report on reversible thermally driven microfluidic pumping enabled by two-way shape memory polymers. After developing a suitable shape memory polymer (SMP) through variation in the crosslink density, thin and flexible microfluidic devices were constructed by lamination of plastic films with channels defined by laser-cutting of double-sided adhesive film. SMP blisters integrated into the devices provide thermally driven pumping, while opposing elastic blisters are used to generate backpressure for reversible operation. Thermal cycling of the device was found to drive reversible fluid flow: upon heating to 60 °C, the SMP rapidly contracted to fill the surface channels with a transparent fluid, and upon cooling to 8 °C the flow reversed and the channel re-filled with black ink. Combined with a metallized backing layer, this device results in refection of incident light at high temperatures and absorption of light (at the portions covered with channels) at low temperatures. We discuss power-free, autonomous applications ranging from thermal regulation of structures to thermal indication via color change.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Waye, Scot

Power electronics that use high-temperature devices pose a challenge for thermal management. With the devices running at higher temperatures and having a smaller footprint, the heat fluxes increase from previous power electronic designs. This project overview presents an approach to examine and design thermal management strategies through cooling technologies to keep devices within temperature limits, dissipate the heat generated by the devices and protect electrical interconnects and other components for inverter, converter, and charger applications. This analysis, validation, and demonstration intends to take a multi-scale approach over the device, module, and system levels to reduce size, weight, and cost.

Technical Requirements for On-Site Thermal Desorption of Solid Media Contaminated with Hazardous Chlorinated Organics

DTIC Science & Technology

1997-09-18

scrubbers , detectable dioxin/furans may occur, since dioxin/furans are much more soluble in organics than in water. Carbon adsorption is frequently...air pollution control device is required. Acid gases may be controlled by using a wet or dry scrubber or by using a coated baghouse. Operating...unit: 1. exit treated waste temperature; 2. baghouse pressure drop, venturi pressure drop, or drop in liquid/gas ratio; 3. waste feed rate; 4

Harvesting Mechanical and Thermal Energy by Combining ZnO Nanowires and NiTi Shape Memory Alloy

DOE PAGES

Radousky, Harry; Qian, Fang; An, Yonghao; ...

2017-02-19

In the expanding world of small scale energy harvesting, the ability to combine thermal and mechanical harvesting is growing ever more important. Here, we demonstrate the feasibility of using ZnO nanowires to harvest both mechanical and low-quality thermal energy in simple, scalable devices. These devices were fabricated on kapton films and used ZnO nanowires with the same growth direction to assure alignment of the piezoelectric potentials of all of the wires. Mechanical harvesting from these devices was demonstrated using a periodic application of force, modeling the motion of the human body. Tapping the device from the top of the devicemore » with a wood stick, for example yielded an Open Circuit Voltage (OCV) of 0.2 - 4 V, which is in an ideal range for device applications. In order to demonstrate thermal harvesting from low quality heat sources, a commercially available Nitinol (Ni-Ti alloy) foil was attached to the nanowire piezoelectric device to create a compound thermoelectric. When bent at room temperature and then heated to 50°C, the Nitinol foil was restored to its original flat shape, which yielded an output voltage of nearly 1 V from the ZnO nanowire device.« less