Progress on TSV technology for Medipix3RX chip

NASA Astrophysics Data System (ADS)

Sarajlić, M.; Pennicard, D.; Smoljanin, S.; Fritzsch, T.; Zoschke, K.; Graafsma, H.

2017-12-01

The progress of Through Silicon Via (TSV) technology for Medipix3RX chip done at DESY is presented here. The goal of this development is to replace the wire bonds in X-ray detectors with TSVs, in order to reduce the dead area between detectors. We obtained the first working chips assembled together with Si based sensors for X-ray detection. The 3D integration technology, including TSV, Re-distribution layer deposition, bump bonding to the Si sensor and bump bonding to the carrier PCB, was done by Fraunhofer Institute IZM in Berlin. After assembly, the module was successfully tested by recording background radiation and making X-ray images of small objects. The active area of the Medipix3RX chip is 14.1 mm×14.1 mm or 256×256 pixels. During TSV processing, the Medipix3RX chip was thinned from 775 μm original thickness, to 130 μm. The diameter of the vias is 40 μm, and the pitch between the vias is 120 μm. A liner filling approach was used to contact the TSV with the RDL on the backside of the Medipix3RX readout chip.

An experimental investigation on the thermal field of overlapping layers in laser-assisted tape winding process

NASA Astrophysics Data System (ADS)

Hosseini, S. M. A.; Baran, I.; Akkerman, R.

2018-05-01

The laser-assisted tape winding (LATW) is an automated process for manufacturing fiber-reinforced thermoplastic tubular products, such as pipes and pressure vessels. Multi-physical phenomena such as heat transfer, mechanical bonding, phase changes and solid mechanics take place during the process. These phenomena need to be understood and described well for an improved product reliability. Temperature is one of the important parameters in this process to control and optimize the product quality which can be employed in an intelligent model-based inline control system. The incoming tape can overlap with the already wounded layer during the process based on the lay-up configuration. In this situation, the incoming tape can step-on or step-off to an already deposited layer/laminate. During the overlapping, the part temperature changes due to the variation of the geometry caused by previously deposited layer, i.e. a bump geometry. In order to qualify the temperature behavior at the bump regions, an experimental set up is designed on a flat laminate. Artificial bumps/steps are formed on the laminate with various thicknesses and fiber orientations. As the laser head experiences the step-on and step-off, the IR (Infra-Red) camera and the embedded thermocouples measure the temperature on the surface and inside the laminate, respectively. During the step-on, a small drop in temperature is observed while in step-off a higher peak in temperature is observed. It can be concluded that the change in the temperature during overlapping is due to the change in laser incident angle made by the bump geometry. The effect of the step thickness on the temperature peak is quantified and found to be significant.

Flip-chip assembly and reliability using gold/tin solder bumps

NASA Astrophysics Data System (ADS)

Oppermann, Hermann; Hutter, Matthias; Klein, Matthias; Reichl, Herbert

2004-09-01

Au/Sn solder bumps are commonly used for flip chip assembly of optoelectronic and RF devices. They allow a fluxless assembly which is required to avoid contamination at optical interfaces. Flip chip assembly experiments were carried out using as plated Au/Sn bumps without prior bump reflow. An RF and reliability test vehicles comprise a GaAs chip which was flip chip soldered on a silicon substrate. Temperature cycling tests with and without underfiller were performed and the results are presented. The different failure modes for underfilled and non-underfilled samples were discussed and compared. Additional reliability tests were performed with flip chip bonding by gold thermocompression for comparison. The test results and the failure modes are discussed in detail.

Design, processing and testing of LSI arrays: Hybrid microelectronics task

NASA Technical Reports Server (NTRS)

Himmel, R. P.; Stuhlbarg, S. M.; Ravetti, R. G.; Zulueta, P. J.

1979-01-01

Mathematical cost factors were generated for both hybrid microcircuit and printed wiring board packaging methods. A mathematical cost model was created for analysis of microcircuit fabrication costs. The costing factors were refined and reduced to formulae for computerization. Efficient methods were investigated for low cost packaging of LSI devices as a function of density and reliability. Technical problem areas such as wafer bumping, inner/outer leading bonding, testing on tape, and tape processing, were investigated.

Advanced processing of CdTe pixel radiation detectors

NASA Astrophysics Data System (ADS)

Gädda, A.; Winkler, A.; Ott, J.; Härkönen, J.; Karadzhinova-Ferrer, A.; Koponen, P.; Luukka, P.; Tikkanen, J.; Vähänen, S.

2017-12-01

We report a fabrication process of pixel detectors made of bulk cadmium telluride (CdTe) crystals. Prior to processing, the quality and defect density in CdTe material was characterized by infrared (IR) spectroscopy. The semiconductor detector and Flip-Chip (FC) interconnection processing was carried out in the clean room premises of Micronova Nanofabrication Centre in Espoo, Finland. The chip scale processes consist of the aluminum oxide (Al2O3) low temperature thermal Atomic Layer Deposition (ALD), titanium tungsten (TiW) metal sputtering depositions and an electroless Nickel growth. CdTe crystals with the size of 10×10×0.5 mm3 were patterned with several photo-lithography techniques. In this study, gold (Au) was chosen as the material for the wettable Under Bump Metalization (UBM) pads. Indium (In) based solder bumps were grown on PSI46dig read out chips (ROC) having 4160 pixels within an area of 1 cm2. CdTe sensor and ROC were hybridized using a low temperature flip-chip (FC) interconnection technique. The In-Au cold weld bonding connections were successfully connecting both elements. After the processing the detector packages were wire bonded into associated read out electronics. The pixel detectors were tested at the premises of Finnish Radiation Safety Authority (STUK). During the measurement campaign, the modules were tested by exposure to a 137Cs source of 1.5 TBq for 8 minutes. We detected at the room temperature a photopeak at 662 keV with about 2 % energy resolution.

Realization of MEMS-IC Vertical Integration Utilizing Smart Bumpless Bonding

NASA Astrophysics Data System (ADS)

Shiozaki, Masayoshi; Moriguchi, Makoto; Sasaki, Sho; Oba, Masatoshi

This paper reports fundamental technologies, properties, and new experimental results of SBB (Smart Bumpless Bonding) to realize MEMS-IC vertical integration. Although conventional bonding technologies have had difficulties integrating MEMS and its processing circuit because of their rough bonding surfaces, fragile structures, and thermal restriction, SBB technology realized the vertical integration without thermal treatment, any adhesive materials including bumps, and chemical mechanical polishing. The SBB technology bonds sealing parts for vacuum sealing and electrodes for electrical connection simultaneously as published in previous experimental study. The plasma CVD SiO2 is utilized to realize vacuum sealing as sealing material. And Au projection studs are formed on each electrode and connected electrically between two wafers by compressive plastic deformation and surface activation. In this paper, new experimental results including vacuum sealing properties, electrical improvement, IC bonding results on the described fundamental concept and properties are reported.

New results on diamond pixel sensors using ATLAS frontend electronics

NASA Astrophysics Data System (ADS)

Keil, M.; Adam, W.; Berdermann, E.; Bergonzo, P.; de Boer, W.; Bogani, F.; Borchi, E.; Brambilla, A.; Bruzzi, M.; Colledani, C.; Conway, J.; D'Angelo, P.; Dabrowski, W.; Delpierre, P.; Dulinski, W.; Doroshenko, J.; Doucet, M.; van Eijk, B.; Fallou, A.; Fischer, P.; Fizzotti, F.; Kania, D.; Gan, K. K.; Grigoriev, E.; Hallewell, G.; Han, S.; Hartjes, F.; Hrubec, J.; Husson, D.; Kagan, H.; Kaplon, J.; Kass, R.; Knöpfle, K. T.; Koeth, T.; Krammer, M.; Logiudice, A.; mac Lynne, L.; Manfredotti, C.; Meier, D.; Menichelli, D.; Meuser, S.; Mishina, M.; Moroni, L.; Noomen, J.; Oh, A.; Pan, L. S.; Pernicka, M.; Perera, L.; Riester, J. L.; Roe, S.; Rudge, A.; Russ, J.; Sala, S.; Sampietro, M.; Schnetzer, S.; Sciortino, S.; Stelzer, H.; Stone, R.; Suter, B.; Trischuk, W.; Tromson, D.; Vittone, E.; Weilhammer, P.; Wermes, N.; Wetstein, M.; Zeuner, W.; Zoeller, M.

2003-03-01

Diamond is a promising sensor material for future collider experiments due to its radiation hardness. Diamond pixel sensors have been bump bonded to an ATLAS pixel readout chip using PbSn solder bumps. Single chip devices have been characterised by lab measurements and in a high-energy pion beam at CERN. Results on charge collection, spatial resolution, efficiency and the charge carrier lifetime are presented.

Characterization of low temperature Cu/In bonding for fine-pitch interconnects in three-dimensional integration

NASA Astrophysics Data System (ADS)

Panchenko, Iuliana; Bickel, Steffen; Meyer, Jörg; Mueller, Maik; Wolf, Jürgen M.

2018-02-01

This study presents the results for Cu/In bonding based on the solid-liquid interdiffusion (SLID) principle for fine-pitch interconnects in three-dimensional integration. The microbumps were fabricated on Si wafers (55 µm pitch, 25 µm top bump diameter, 35 µm bottom bump diameter). In was electroplated directly on Cu only on the top die microbumps. Two different In thicknesses were manufactured (3 and 5 µm). The interconnects were successfully fabricated at a bonding temperature of 170 °C. High temperature storage was carried out at 150 and 200 °C for different times between 2 and 72 h directly after the interconnect formation in order to investigate the temperature stability. The microstructure was analyzed by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The intermetallic compound (IMC) found in the microbumps after electroplating was CuIn2. The intermetallic interlayer consists of Cu11In9 and a thin layer of Cu2In after bonding and isothermal storage.

Investigation of electromigration behavior in lead-free flip chip solder bumps

NASA Astrophysics Data System (ADS)

Kalkundri, Kaustubh Jayant

Packaging technology has also evolved over time in an effort to keep pace with the demanding requirements. Wirebond and flip chip packaging technologies have become extremely versatile and ubiquitous in catering to myriad applications due to their inherent potential. This research is restricted strictly to flip chip technology. This technology incorporates a process in which the bare chip is turned upside down, i.e., active face down, and is bonded through the I/O to the substrate, hence called flip chip. A solder interconnect that provides electrical connection between the chip and substrate is bumped on a processed silicon wafer prior to dicing for die-attach. The assembly is then reflow-soldered followed by the underfill process to provide the required encapsulation. The demand for smaller and lighter products has increased the number of I/Os without increasing the package sizes, thereby drastically reducing the size of the flip chip solder bumps and their pitch. Reliability assessment and verification of these devices has gained tremendous importance due to their shrinking size. To add to the complexity, changing material sets that are results of recently enacted lead-free solder legislations have raised some compatibility issues that are already being researched. In addition to materials and process related flip chip challenges such as solder-flux compatibility, Coefficient of Thermal Expansion (CTE) mismatch, underfill-flux compatibility and thermal management, flip chip packages are vulnerable to a comparatively newer challenge, namely electromigration observed in solder bumps. It is interesting to note that electromigration has come to the forefront of challenges only recently. It has been exacerbated by the reduction in bump cross-section due to the seemingly continuous shrinking in package size over time. The focus of this research was to understand the overall electromigration behavior in lead-free (SnAg) flip chip solder bumps. The objectives of the research were to comprehend the physics of failure mechanism in electromigration for lead-free solder bumps assembled in a flip chip ceramic package having thick copper under bump metallization and to estimate the unknown critical material parameters from Black's equation that describe failure due to electromigration. In addition, the intent was to verify the 'use condition reliability' by extrapolation from experimental conditions. The methodology adopted for this research was comprised of accelerated electromigration tests on SnAg flip chip solder bumps assembled on ceramic substrate with a thick copper under bump metallization. The experimental approach was comprised of elaborate measurement of the temperature of each sample by separate metallization resistance exhibiting positive resistance characteristics to overcome the variation in Joule heating. After conducting the constant current experiments and analyzing the failed samples, it was found that the primary electromigration failure mode observed was the dissolution of the thick copper under bump metallization in the solder, leading to a change in resistance. The lifetime data obtained from different experiments was solved simultaneously using a multiple regression approach to yield the unknown Black's equation parameters of current density exponent and activation energy. In addition to the implementation of a systematic failure analysis and data analysis procedure, it was also deduced that thermomigration due to the temperature gradient across the chip does impact the overall electromigration behavior. This research and the obtained results were significant in bridging the gap for an overall understanding of this critical failure mode observed in flip chip solder bumps. The measurement of each individual sample temperature instead of an average temperature enabled an accurate analysis for predicting the 'use condition reliability' of a comparable product. The obtained results and the conclusions can be used as potential inputs in future designs and newer generations of flip chip devices that might undergo aggressive scaling. This will enable these devices to retain their functionality during their intended useful life with minimal threat of failure due to the potent issue of electromigration. (Abstract shortened by UMI.)

High performance low cost interconnections for flip chip attachment with electrically conductive adhesive. Final report

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

NONE

1998-05-01

This final report is a compilation of final reports from each of the groups participating in the program. The main three groups involved in this effort are the Thomas J. Watson Research Center of IBM Corporation in Yorktown Heights, New York, Assembly Process Design of IBM Corporation in Endicott, New York, and SMT Laboratory of Universal Instruments Corporation in Binghamton, New York. The group at the research center focused on the conductive adhesive materials development and characterization. The group in process development focused on processing of the Polymer-Metal-Solvent Paste (PMSP) to form conductive adhesive bumps, formation of the Polymer-Metal Compositemore » (PMC) on semiconductor devices and study of the bonding process to circuitized organic carriers, and the long term durability and reliability of joints formed using the process. The group at Universal Instruments focused on development of an equipment set and bonding parameters for the equipment to produce bond assembly tooling. Reports of each of these individual groups are presented here reviewing their technical efforts and achievements.« less

Module comprising IC memory stack dedicated to and structurally combined with an IC microprocessor chip

NASA Technical Reports Server (NTRS)

Carson, John C. (Inventor); Indin, Ronald J. (Inventor); Shanken, Stuart N. (Inventor)

1994-01-01

A computer module is disclosed in which a stack of glued together IC memory chips is structurally integrated with a microprocessor chip. The memory provided by the stack is dedicated to the microprocessor chip. The microprocessor and its memory stack may be connected either by glue and/or by solder bumps. The solder bumps can perform three functions--electrical interconnection, mechanical connection, and heat transfer. The electrical connections in some versions are provided by wire bonding.

Apparatus for Precise Indium-Bump Bonding of Microchips

NASA Technical Reports Server (NTRS)

Wild, Larry; Mulder, Jerry; Alvarado, Nicholas

2005-01-01

An improved apparatus has been designed and built for use in precise positioning and pressing of a microchip onto a substrate (which could, optionally, be another microchip) for the purpose of indium-bump bonding. The apparatus (see figure) includes the following: A stereomicroscope, A stage for precise positioning of the microchip in rotation angle (theta) about the nominally vertical pressing axis and in translation along two nominally horizontal coordinate axes (x and y), and An actuator system that causes a bonding tip to press the microchip against the substrate with a precisely controlled force. In operation, the microscope and the stage are used to position the microchip under the bonding tip and to align the indium bumps on the chip and the substrate, then the actuator system is used to apply a prescribed bonding force for a prescribed time. The improved apparatus supplants a partly similar prior apparatus that operated with less precision and repeatability, producing inconsistent and unreliable bonds. Results of the use of the prior apparatus included broken microchips, uneven bonds, and bonds characterized, variously, by overcompression or undercompression. In that apparatus, the bonding force was generated and controlled by use of a micrometer head positioned over the center of a spring-loaded scale, and the force was applied to the microchip via the scale, which was equipped for digital readout of the force. The inconsistency of results was attributed to the following causes: It was not possible to control the bonding force with sufficient precision or repeatability. Particularly troublesome was the inability to control the force at levels less than the weight of 150 g. Excessive compliance in the spring-loaded scale, combined with deviations from parallelarity of the substrate and bonding-tip surfaces, gave rise to nonuniformity in the pressure applied to the microchip, thereby generating excessive stresses and deformations in the microchip. In the improved apparatus, the bonding tip and the components that hold the substrate and the microchip are more rigid and precise than in the prior apparatus, so as to ensure less deviation from parallelarity of the bonding-tip and substrate surfaces, thereby ensuring more nearly uniform distribution of bonding force over the area of the microchip. The bonding force is now applied through, and measured by, a load cell that makes it possible to exert finer control over the force. The force can be set at any value between 0 and the weight of 800 g in increments of 0.2 g.

Improved Reliability of SiC Pressure Sensors for Long Term High Temperature Applications

NASA Technical Reports Server (NTRS)

Okojie, R. S.; Nguyen, V.; Savrun, E.; Lukco, D.

2011-01-01

We report advancement in the reliability of silicon carbide pressure sensors operating at 600 C for extended periods. The large temporal drifts in zero pressure offset voltage at 600 C observed previously were significantly suppressed to allow improved reliable operation. This improvement was the result of further enhancement of the electrical and mechanical integrity of the bondpad/contact metallization, and the introduction of studded bump bonding on the pad. The stud bump contact promoted strong adhesion between the Au bond pad and the Au die-attach. The changes in the zero offset voltage and bridge resistance over time at temperature were explained by the microstructure and phase changes within the contact metallization, that were analyzed with Auger electron spectroscopy (AES) and field emission scanning electron microscopy (FE-SEM).

Microfabricated Electrical Connector for Atomic Force Microscopy Probes with Integrated Sensor/Actuator

NASA Astrophysics Data System (ADS)

Akiyama, Terunobu; Staufer, Urs; Rooij, Nico F. de

2002-06-01

A microfabricated, electrical connector is proposed for facilitating the mounting of atomic force microscopy (AFM) probes, which have an integrated sensor and/or actuator. Only a base chip, which acts as a socket, is permanently fixed onto a printed circuit board and electronically connected by standard wire bonding. The AFM chip, the “plug”, is flipped onto the base chip and pressed from the backside by a spring. Electrical contact with the eventual stress sensors, capacitive or piezoelectric sensor/actuators, is provided by contact bumps. These bumps of about 8 μm height are placed onto the base chip. They touch the pads on the AFM chip that were originally foreseen to be for wire bonding and thus provide the electrical contact. This connector schema was successfully used to register AFM images with piezoresistive cantilevers.

A short review on thermosonic flip chip bonding

NASA Astrophysics Data System (ADS)

Suppiah, Sarveshvaran; Ong, Nestor Rubio; Sauli, Zaliman; Sarukunaselan, Karunavani; Alcain, Jesselyn Barro; Shahimin, Mukhzeer Mohamad; Retnasamy, Vithyacharan

2017-09-01

This review is to study the evolution and key findings, critical technical challenges, solutions and bonding equipment of thermosonic flip chip bonding. Based on the review done, it was found that ultrasonic power, bonding time and force are the three main critical parameters need to be optimized in order to achieve sound and reliable bonding between the die and substrate. A close monitoring of the ultrasonic power helped to prevent over bonding phenomena on flexible substrate. Gold stud bumping is commonly used in thermosonic bonding compared to solder due to its better reliability obtained in the LED and optoelectronic packages. The review comprised short details on the available thermosonic bonding equipment in the semiconductor industry as well.

Chemical effect on diffusion in intermetallic compounds

NASA Astrophysics Data System (ADS)

Chen, Yi-Ting

With the trend of big data and the Internet of things, we live in a world full of personal electronic devices and small electronic devices. In order to make the devices more powerful, advanced electronic packaging such as wafer level packaging or 3D IC packaging play an important role. Furthermore, ?-bumps, which connect silicon dies together with dimension less than 10 ?m, are crucial parts in advanced packaging. Owing to the dimension of ?-bumps, they transform into intermetallic compound from tin based solder after the liquid state bonding process. Moreover, many new reliability issues will occur in electronic packaging when the bonding materials change; in this case, we no longer have tin based solder joint, instead, we have intermetallic compound ?-bumps. Most of the potential reliability issues in intermetallic compounds are caused by the chemical reactions driven by atomic diffusion in the material; thus, to know the diffusivities of atoms inside a material is significant and can help us to further analyze the reliability issues. However, we are lacking these kinds of data in intermetallic compound because there are some problems if used traditional Darken's analysis. Therefore, we considered Wagner diffusivity in our system to solve the problems and applied the concept of chemical effect on diffusion by taking the advantage that large amount of energy will release when compounds formed. Moreover, by inventing the holes markers made by Focus ion beam (FIB), we can conduct the diffusion experiment and obtain the tracer diffusivities of atoms inside the intermetallic compound. We applied the technique on Ni3Sn4 and Cu3Sn, which are two of the most common materials in electronic packaging, and the tracer diffusivities are measured under several different temperatures; moreover, microstructure of the intermetallic compounds are investigated to ensure the diffusion environment. Additionally, the detail diffusion mechanism was also discussed in aspect of diffusion activation enthalpy and diffusion pre-factor by using lattice structure simulation. Last but not the least, X-ray photoelectron spectroscopy and First principal calculation simulation were used to observe the electron binding energies in the intermetallic compound and illustrate the partial covalent bonding behavior in the intermetallic compounds.

CVD diamond pixel detectors for LHC experiments

NASA Astrophysics Data System (ADS)

Wedenig, R.; Adam, W.; Bauer, C.; Berdermann, E.; Bergonzo, P.; Bogani, F.; Borchi, E.; Brambilla, A.; Bruzzi, M.; Colledani, C.; Conway, J.; Dabrowski, W.; Delpierre, P.; Deneuville, A.; Dulinski, W.; van Eijk, B.; Fallou, A.; Fizzotti, F.; Foulon, F.; Friedl, M.; Gan, K. K.; Gheeraert, E.; Grigoriev, E.; Hallewell, G.; Hall-Wilton, R.; Han, S.; Hartjes, F.; Hrubec, J.; Husson, D.; Kagan, H.; Kania, D.; Kaplon, J.; Karl, C.; Kass, R.; Knöpfle, K. T.; Krammer, M.; Logiudice, A.; Lu, R.; Manfredi, P. F.; Manfredotti, C.; Marshall, R. D.; Meier, D.; Mishina, M.; Oh, A.; Pan, L. S.; Palmieri, V. G.; Pernicka, M.; Peitz, A.; Pirollo, S.; Polesello, P.; Pretzl, K.; Procario, M.; Re, V.; Riester, J. L.; Roe, S.; Roff, D.; Rudge, A.; Runolfsson, O.; Russ, J.; Schnetzer, S.; Sciortino, S.; Speziali, V.; Stelzer, H.; Stone, R.; Suter, B.; Tapper, R. J.; Tesarek, R.; Trawick, M.; Trischuk, W.; Vittone, E.; Wagner, A.; Walsh, A. M.; Weilhammer, P.; White, C.; Zeuner, W.; Ziock, H.; Zoeller, M.; Blanquart, L.; Breugnion, P.; Charles, E.; Ciocio, A.; Clemens, J. C.; Dao, K.; Einsweiler, K.; Fasching, D.; Fischer, P.; Joshi, A.; Keil, M.; Klasen, V.; Kleinfelder, S.; Laugier, D.; Meuser, S.; Milgrome, O.; Mouthuy, T.; Richardson, J.; Sinervo, P.; Treis, J.; Wermes, N.; RD42 Collaboration

1999-08-01

This paper reviews the development of CVD diamond pixel detectors. The preparation of the diamond pixel sensors for bump-bonding to the pixel readout electronics for the LHC and the results from beam tests carried out at CERN are described.

Photodiodes integration on a suspended ridge structure VOA using 2-step flip-chip bonding method

NASA Astrophysics Data System (ADS)

Kim, Seon Hoon; Kim, Tae Un; Ki, Hyun Chul; Kim, Doo Gun; Kim, Hwe Jong; Lim, Jung Woon; Lee, Dong Yeol; Park, Chul Hee

2015-01-01

In this works, we have demonstrated a VOA integrated with mPDs, based on silica-on-silicon PLC and flip-chip bonding technologies. The suspended ridge structure was applied to reduce the power consumption. It achieves the attenuation of 30dB in open loop operation with the power consumption of below 30W. We have applied two-step flipchip bonding method using passive alignment to perform high density multi-chip integration on a VOA with eutectic AuSn solder bumps. The average bonding strength of the two-step flip-chip bonding method was about 90gf.

Silver flip chip interconnect technology and solid state bonding

NASA Astrophysics Data System (ADS)

Sha, Chu-Hsuan

In this dissertation, fluxless transient liquid phase (TLP) bonding and solid state bonding between thermal expansion mismatch materials have been developed using Ag-In binary systems, pure Au, Ag, and Cu-Ag composite. In contrast to the conventional soldering process, fluxless bonding technique eliminates any corrosion and contamination problems caused by flux. Without flux, it is possible to fabricate high quality joints in large bonding areas where the flux is difficult to clean entirely. High quality joints are crucial to bonding thermal expansion mismatch materials since shear stress develops in the bonded pair. Stress concentration at voids in joints could increases breakage probability. In addition, intermetallic compound (IMC) formation between solder and underbump metallurgy (UBM) is essential for interconnect joint formation in conventional soldering process. However, the interface between IMC and solder is shown to be the weak interface that tends to break first during thermal cycling and drop tests. In our solid state bonding technique, there is no IMC involved in the bonding between Au to Au, Ag and Cu, and Ag and Au. All the reliability issues related to IMC or IMC growth is not our concern. To sum up, ductile bonding media, such as Ag or Au, and proper metallic layered structure are utilized in this research to produce high quality joints. The research starts with developing a low temperature fluxless bonding process using electroplated Ag/In/Ag multilayer structures between Si chip and 304 stainless steel (304SS) substrate. Because the outer thin Ag layer effectively protects inner In layer from oxidation, In layer dissolves Ag layer and joints to Ag layer on the to-be-bonded Si chip when temperature reaches the reflow temperature of 166ºC. Joints consist of mainly Ag-rich Ag-In solid solution and Ag2In. Using this fluxless bonding technique, two 304SS substrates can be bonded together as well. From the high magnification SEM images taken at cross-section, there is no void or gap observed. The new bonding technique presented should be valuable in packaging high power electronic devices for high temperature operations. It should also be useful to bond two 304SS parts together at low bonding temperature of 190ºC. Solid state bonding technique is then introduced to bond semiconductor chips, such as Si, to common substrates, such as Cu or alumina, using pure Ag and Au at a temperature matching the typical reflow temperature used in packaging industries, 260°C. In bonding, we realize the possibilities of solid state bonding of Au to Au, Au to Ag, and Ag to Cu. The idea comes from that Cu, Ag, and Au are located in the same column on periodic table, meaning that they have similar electronic configuration. They therefore have a better chance to share electrons. Also, the crystal lattice of Cu, Ag, and Au is the same, face-centered cubic. In the project, the detailed bonding mechanism is beyond the scope and here we determine the bonding by the experimental result. Ag is chosen as the joint material because of its superior physical properties. It has the highest electrical and thermal conductivities among all metals. It has low yield strength and is relatively ductile. Au is considered as well because its excellent ductility and fatigue resistance. Thus, the Ag or Au joints can deform to accommodate the shear strain caused by CTE mismatch between Si and Cu. Ag and Au have melting temperatures higher than 950°C, so the pure Ag or Au joints are expected to sustain in high operating temperature. The resulting joints do not contain any intermetallic compound. Thus, all reliability issues associated with intermetallic growth in commonly used solder joints do not exist anymore. We finally move to the applications of solid state Ag bonding in flip chip interconnects design. At present, nearly all large-scale integrated circuit (IC) chips are packaged with flip-chip technology. This means that the chip is flipped over and the active (front) side is connected to the package using a large number of tiny solder joints, which provide mechanical support, electrical connection, and heat conduction. For chip-to-package level interconnects, a challenge is the severe mismatch in coefficient of thermal expansion (CTE) between chips and package substrates. The interconnect material thus needs to be compliant to deal with the CTE mismatch. At present, nearly all flip-chip interconnects in electronic industries are made of lead-free Sn-based solders. Soft solders are chosen due to high ductility, low yield strength, relatively low melting temperature, and reasonably good electrical and thermal conductivities. In the never ending scaling down trend, more and more transistors are placed on the same Si chip size. This results in larger pin-out numbers and smaller solder joints. According to International Technology Roadmap for Semiconductors (ITRS), by 2018, the pitch in flip-chip interconnects will become smaller than 70mum for high performance applications. Two problems occur. The first is increase in shear strain. The aspect ratio of flip-chip joints is constrained to 0.7 because it goes through molten phase in the reflow process. Therefore, smaller joints become shorter as well, resulting in larger shear strain arising from CTE mismatch between Si chips and package substrates. The second is increase in stress in the joints. Since intermetallic (IMC) thickness in the joint does not scale down with joint size, ratio of IMC thickness to joint height increases. This further enlarges the shear stress because the IMC does not deform as the soft solder does to accommodate CTE mismatch. In this research, the smallest dimension we achieve for Ag flip chip interconnect joint is 15mum in diameter. The ten advantages of Ag flip chip interconnect technology can be identified as (a) High electrical conductivity, 7.7 times of that of Pb-free solders, (b) High thermal conductivity, 5.2 times of that of Pb-free solders, (c) Completely fluxless, (d) No IMCs; all reliability issues associated with IMC and IMC growth do not exist, (e) Ag is very ductile and can manage CTE mismatch between chips and packages, (f) Ag joints can sustain at very high operation temperature because Ag has high melting temperature of 961°C, (g) No molten phase involved; the bump can better keep its shape and geometry, (h) No molten phase involved; bridging of adjacent bumps is less likely to occur, i. Aspect ratio of bumps can be made greater than 1, (j) The size of the bumps is only limited by the lithographic process. Cu-Ag composite flip chip interconnect joints is developed based on three reasons. The first is lower material cost. The second is to strengthen the columns because the yield strength of Cu is 6 times of that of Ag. The third is to avoid possible Ag migration between Ag electrodes under voltage at temperatures above 250°C. This Cu-Ag composite design presents a solution in the path to the scale down roadmap.

Platform technologies for hybrid optoelectronic integration and packaging

NASA Astrophysics Data System (ADS)

Datta, Madhumita

In order to bring fiber-optics closer to individual home and business services, the optical network components have to be inexpensive and reliable. Integration and packaging of optoelectronic devices holds the key to high-volume low-cost component manufacturing. The goal of this dissertation is to propose, study, and demonstrate various ways to integrate optoelectronic devices on a packaging platform to implement cost-effective, functional optical modules. Two types of hybrid integration techniques have been proposed: flip-chip solder bump bonding for high-density two-dimensional array packaging of surface-emitting devices, and solder preform bonding for fiber-coupled edge-emitting semiconductor devices. For flip-chip solder bump bonding, we developed a simple, inexpensive remetallization process called "electroless plating", which converts the aluminum bond pads of foundry-made complementary metal oxide semiconductor (CMOS) chips into solder-bondable and wire-bondable gold surfaces. We have applied for a patent on this remetallization technique. For fiber-pigtailed edge-emitting laser modules, we have studied the coupling characteristics of different types of lensed single-mode fibers including semispherically lensed fiber, cylindrically lensed fiber and conically lensed fiber. We have experimentally demonstrated 66% coupling efficiency with semispherically lensed fiber and 50% efficiency with conically lensed fibers. We have proposed and designed a packaging platform on which lensed fibers can be actively aligned to a laser and solder-attached reliably to the platform so that the alignment is retained. We have designed thin-film nichrome heaters on fused quartz platforms as local heat source to facilitate on-board solder alignment and attachment of fiber. The thermal performance of the heaters was simulated using finite element analysis tool ANSYS prior to fabrication. Using the heater's reworkability advantage, we have estimated the shift of the fiber due to solder shrinkage and introduced a pre-correction in the alignment process to restore optimum coupling efficiency close to 50% with conically lensed fibers. We have applied for a patent on this unique active alignment method through the University of Maryland's Technology Commercialization Office. Although we have mostly concentrated on active alignment platforms, we have proposed the idea of combining the passive alignment advantages of silicon optical benches to the on-board heater-assisted active alignment technique. This passive-active alignment process has the potential of cost-effective array packaging of edge-emitting devices.

Effect of Current Density and Plating Time on Cu Electroplating in TSV and Low Alpha Solder Bumping

NASA Astrophysics Data System (ADS)

Jung, Do-Hyun; Sharma, Ashutosh; Kim, Keong-Heum; Choo, Yong-Chul; Jung, Jae-Pil

2015-03-01

In this study, copper filling in through-silicon via (TSV) by pulse periodic reverse electroplating and low alpha solder bumping on Cu-filled TSVs was investigated. The via diameter and depth of TSV were 60 and 120 µm, respectively. The experimental results indicated that the thickness of electrodeposited copper layer increased with increasing cathodic current density and plating time. The electroplated Cu in TSV showed a typical bottom-up filling. A defectless, complete, and fast 100% Cu-filled TSV was achieved at cathodic and anodic current densities of -8 and 16 mA/cm2 for a plating time of 4 h, respectively. A sound low alpha solder ball, Sn-1.0 wt.% Ag-0.5 wt.% Cu (SAC 105) with a diameter of 83 µm and height of 66 µm was reflow processed at 245 °C on Cu-filled TSV. The Cu/solder joint interface was subjected to high temperature aging at 85 °C for 150 h, which showed an excellent bonding characteristic with minimum Cu-Sn intermetallic compounds growth.

Analysis of Power Generating Speed Bumps Made of Concrete Foam Composite

NASA Astrophysics Data System (ADS)

Syam, B.; Muttaqin, M.; Hastrino, D.; Sebayang, A.; Basuki, W. S.; Sabri, M.; Abda, S.

2017-03-01

This paper discusses the analysis of speed bump made of concrete foam composite which is used to generate electrical power. Speed bumps are designed to decelerate the speed of vehicles before passing through toll gates, public areas, or any other safety purposes. In Indonesia a speed bump should be designed in the accordance with KM Menhub 3 year 1994. In this research, the speed bump was manufactured with dimensions and geometry comply to the regulation mentioned above. Concrete foam composite speed bumps were used due to its light weight and relatively strong to receive vertical forces from the tyres of vehicles passing over the bumps. The reinforcement materials are processed from empty fruit bunch of oil palm. The materials were subjected to various tests to obtain its physical and mechanical properties. To analyze the structure stability of the speed bumps some models were analyzed using a FEM-based numerical softwares. It was obtained that the speed bumps coupled with polymeric composite bar (3 inches in diameter) are significantly reduce the radial stresses. In addition, the speed bumps equipped with polymeric composite casing or steel casing are also suitable for use as part of system components in producing electrical energy.

Bonding techniques for hybrid active pixel sensors (HAPS)

NASA Astrophysics Data System (ADS)

Bigas, M.; Cabruja, E.; Lozano, M.

2007-05-01

A hybrid active pixel sensor (HAPS) consists of an array of sensing elements which is connected to an electronic read-out unit. The most used way to connect these two different devices is bump bonding. This interconnection technique is very suitable for these systems because it allows a very fine pitch and a high number of I/Os. However, there are other interconnection techniques available such as direct bonding. This paper, as a continuation of a review [M. Lozano, E. Cabruja, A. Collado, J. Santander, M. Ullan, Nucl. Instr. and Meth. A 473 (1-2) (2001) 95-101] published in 2001, presents an update of the different advanced bonding techniques available for manufacturing a hybrid active pixel detector.

Geiger-Mode Avalanche Photodiode Arrays Integrated to All-Digital CMOS Circuits

DTIC Science & Technology

2016-01-20

Figure 7 4×4 GMAPD array wire bonded to CMOS timing circuits Figure 8 Low‐fill‐factor APD design used in lidar sensors The APD doping...epitaxial growth and the pixels are isolated by mesa etch. 128×32 lidar image sensors were built by bump bonding the APD arrays to a CMOS timing...passive image sensor with this large a format based on hybridization of a GMAPD array to a CMOS readout. Fig. 14 shows one of the first images taken

Effect of Interfacial Microstructures on the Bonding Strength of Sn-3.0Ag-0.5Cu Pb-Free Solder Bump

NASA Astrophysics Data System (ADS)

Kim, Jae-Myeong; Jeong, Myeong-Hyeok; Yoo, Sehoon; Park, Young-Bae

2012-05-01

The effect of interfacial microstructures on the bonding strength of Sn-3.0Ag-0.5Cu Pb-free solder bumps with respect to the loading speed, annealing time, and surface finish was investigated. The shear strength increased and the ductility decreased with increasing shear speed, primarily because of the time-independent plastic hardening and time-dependent strain-rate sensitivity of the solder alloy. The shear strength and toughness decreased for all surface finishes under the high-speed shear test of 500 mm/s as a result of increasing intermetallic compound (IMC) growth and pad interface weakness associated with increased annealing time. The immersion Sn and organic solderability preservative (OSP) finishes showed lower shear strength compared to the electroless nickel immersion gold (ENIG) finish. With increasing annealing time, the ENIG finish exhibited the pad open fracture mode, whereas the immersion Sn and OSP finishes exhibited the brittle fracture mode. In addition, the shear strength of the solder joints was correlated with each fracture mode.

Properties of various plasma surface treatments for low-temperature Au–Au bonding

NASA Astrophysics Data System (ADS)

Yamamoto, Michitaka; Higurashi, Eiji; Suga, Tadatomo; Sawada, Renshi; Itoh, Toshihiro

2018-04-01

Atmospheric-pressure (AP) plasma treatment using three different types of gases (an argon-hydrogen mixed gas, an argon-oxygen mixed gas, and a nitrogen gas) and low-pressure (LP) plasma treatment using an argon gas were compared for Au–Au bonding with thin films and stud bumps at low temperature (25 or 150 °C) in ambient air. The argon-hydrogen gas mixture AP plasma treatment and argon LP plasma treatment were found to distinctly increase the shear bond strength for both samples at both temperatures. From X-ray photoelectron spectroscopy (XPS) analysis, the removal of organic contaminants on Au surfaces without the formation of hydroxyl groups and gold oxide is considered effective in increasing the Au–Au bonding strength at low temperature.

Mean-time-to-failure study of flip chip solder joints on Cu/Ni(V)/Al thin-film under-bump-metallization

NASA Astrophysics Data System (ADS)

Choi, W. J.; Yeh, E. C. C.; Tu, K. N.

2003-11-01

Electromigration of eutectic SnPb flip chip solder joints and their mean-time-to-failure (MTTF) have been studied in the temperature range of 100 to 140 °C with current densities of 1.9 to 2.75×104 A/cm2. In these joints, the under-bump-metallization (UBM) on the chip side is a multilayer thin film of Al/Ni(V)/Cu, and the metallic bond-pad on the substrate side is a very thick, electroless Ni layer covered with 30 nm of Au. When stressed at the higher current densities, the MTTF was found to decrease much faster than what is expected from the published Black's equation. The failure occurred by interfacial void propagation at the cathode side, and it is due to current crowding near the contact interface between the solder bump and the thin-film UBM. The current crowding is confirmed by a simulation of current distribution in the solder joint. Besides the interfacial void formation, the intermetallic compounds formed on the UBM as well as the Ni(V) film in the UBM have been found to dissolve completely into the solder bump during electromigration. Therefore, the electromigation failure is a combination of the interfacial void formation and the loss of UBM. Similar findings in eutectic SnAgCu flip chip solder joints have also been obtained and compared.

Optical technologies for TSV inspection

NASA Astrophysics Data System (ADS)

Aiyer, Arun A.; Maltsev, Nikolai; Ryu, Jae

2014-04-01

In this paper, Frontier Semiconductor will introduce a new technology that is referred to as Virtual Interface Technology (VIT™). VIT™ is a Fourier domain technique that utilizes temporal phase shear of the measurement beam. The unique configuration of the sensor enables measurement of wafer and bonded stack thicknesses ranging from a few microns to millimeters with measurement repeatability ~ nm and resolution of approximately 0.1% of nominal thickness or depth. We will present data on high aspect ratio via measurements (depth, top critical dimension, bottom critical dimension, via bottom profile and side wall angle), bonded wafer stack thickness, and Cu bump measurements. A complimentary tool developed at FSM is a high resolution μRaman spectrometer to measure stress-change in Si lattice induced by Through Silicon Via (TSV) processes. These measurements are important to determine Keep-Out-Zone in the areas where devices are built so that the engineered gate strain is not altered by TSV processing induced strain. Applications include via post-etch; via post fill, and bottom Cu nail stress measurements. The capabilities of and measurement results from both tools are discussed below.

Experiences in flip chip production of radiation detectors

NASA Astrophysics Data System (ADS)

Savolainen-Pulli, Satu; Salonen, Jaakko; Salmi, Jorma; Vähänen, Sami

2006-09-01

Modern imaging devices often require heterogeneous integration of different materials and technologies. Because of yield considerations, material availability, and various technological limitations, an extremely fine pitch is necessary to realize high-resolution images. Thus, there is a need for a hybridization technology that is able to join together readout amplifiers and pixel detectors at a very fine pitch. This paper describes radiation detector flip chip production at VTT. Our flip chip technology utilizes 25-μm diameter tin-lead solder bumps at a 50-μm pitch and is based on flux-free bonding. When preprocessed wafers are used, as is the case here, the total yield is defined only partly by the flip chip process. Wafer preprocessing done by a third-party silicon foundry and the flip chip process create different process defects. Wafer-level yield maps (based on probing) provided by the customer are used to select good readout chips for assembly. Wafer probing is often done outside of a real clean room environment, resulting in particle contamination and/or scratches on the wafers. Factors affecting the total yield of flip chip bonded detectors are discussed, and some yield numbers of the process are given. Ways to improve yield are considered, and finally guidelines for process planning and device design with respect to yield optimization are given.

Optimized ultra-thin manganin alloy passivated fine-pitch damascene compatible bump-less Cu-Cu bonding at sub 200 °C for three-dimensional Integration applications

NASA Astrophysics Data System (ADS)

Panigrahi, Asisa Kumar; Hemanth Kumar, C.; Bonam, Satish; Ghosh, Tamal; Rama Krishna Vanjari, Siva; Govind Singh, Shiv

2018-02-01

Enhanced Cu diffusion, Cu surface passivation, and smooth surface at the bonding interface are the key essentials for high quality Cu-Cu bonding. Previously, we have demonstrated optimized 3 nm thin Manganin metal-alloy passivation from oxidation and also helps to reduce the surface roughness to about 0.8 nm which substantially led to high quality Cu-Cu bonding. In this paper, we demonstrated an ultra fine-pitch (<25 µm) Cu-Cu bonding using an optimized Manganin metal-alloy passivation. This engineered surface passivation approach led to high quality bonding at sub 200 °C temperature and 0.4 MPa. Very low specific contact resistance of 1.4 × 10-7 Ω cm2 and the defect free bonded interface is clear indication of high quality bonding for future multilayer integrations. Furthermore, electrical characterization of the bonded structure was performed under various robust conditions as per International Technology Roadmap for Semiconductors (ITRS Roadmap) in order to satisfy the stability of the bonded structure.

Far infrared through millimeter backshort-under-grid arrays

NASA Astrophysics Data System (ADS)

Allen, Christine A.; Abrahams, John; Benford, Dominic J.; Chervenak, James A.; Chuss, David T.; Staguhn, Johannes G.; Miller, Timothy M.; Moseley, S. Harvey; Wollack, Edward J.

2006-06-01

We are developing a large-format, versatile, bolometer array for a wide range of infrared through millimeter astronomical applications. The array design consists of three key components - superconducting transition edge sensor bolometer arrays, quarter-wave reflective backshort grids, and Superconducting Quantum Interference Device (SQUID) multiplexer readouts. The detector array is a filled, square grid of bolometers with superconducting sensors. The backshort arrays are fabricated separately and are positioned in the etch cavities behind the detector grid. The grids have unique three-dimensional interlocking features micromachined into the walls for positioning and mechanical stability. The ultimate goal of the program is to produce large-format arrays with background-limited sensitivity, suitable for a wide range of wavelengths and applications. Large-format (kilopixel) arrays will be directly indium bump bonded to a SQUID multiplexer circuit. We have produced and tested 8×8 arrays of 1 mm detectors to demonstrate proof of concept. 8×16 arrays of 2 mm detectors are being produced for a new Goddard Space Flight Center instrument. We have also produced models of a kilopixel detector grid and dummy multiplexer chip for bump bonding development. We present detector design overview, several unique fabrication highlights, and assembly technologies.

Infrared-Bolometer Arrays with Reflective Backshorts

NASA Technical Reports Server (NTRS)

Miller, Timothy M.; Abrahams, John; Allen, Christine A.

2011-01-01

Integrated circuits that incorporate square arrays of superconducting-transition- edge bolometers with optically reflective backshorts are being developed for use in image sensors in the spectral range from far infrared to millimeter wavelengths. To maximize the optical efficiency (and, thus, sensitivity) of such a sensor at a specific wavelength, resonant optical structures are created by placing the backshorts at a quarter wavelength behind the bolometer plane. The bolometer and backshort arrays are fabricated separately, then integrated to form a single unit denoted a backshort-under-grid (BUG) bolometer array. In a subsequent fabrication step, the BUG bolometer array is connected, by use of single-sided indium bump bonding, to a readout device that comprises mostly a superconducting quantum interference device (SQUID) multiplexer circuit. The resulting sensor unit comprising the BUG bolometer array and the readout device is operated at a temperature below 1 K. The concept of increasing optical efficiency by use of backshorts at a quarter wavelength behind the bolometers is not new. Instead, the novelty of the present development lies mainly in several features of the design of the BUG bolometer array and the fabrication sequence used to implement the design. Prior to joining with the backshort array, the bolometer array comprises, more specifically, a square grid of free-standing molybdenum/gold superconducting-transition-edge bolometer elements on a 1.4- m-thick top layer of silicon that is part of a silicon support frame made from a silicon-on-insulator wafer. The backshort array is fabricated separately as a frame structure that includes support beams and contains a correspond - ing grid of optically reflective patches on a single-crystal silicon substrate. The process used to fabricate the bolometer array includes standard patterning and etching steps that result in the formation of deep notches in the silicon support frame. These notches are designed to interlock with the support beams on the backshort-array structure to provide structural support and precise relative positioning. The backshort-array structure is inserted in the silicon support frame behind the bolometer array, and the notches in the frame serve to receive the support beams of the backshort-array structure and thus determine the distance between the backshort and bolometer planes. The depth of the notches and, thus, the distance between the backshort and bolometer planes, can be tailored to a value between 25 to 300 m adjusting only a few process steps. The backshort array is designed so as not to interfere with the placement of indium bumps for subsequent indium bump-bonding to the multiplexing readout circuitry

3D Printing of Ball Grid Arrays

NASA Astrophysics Data System (ADS)

Sinha, Shayandev; Hines, Daniel; Dasgupta, Abhijit; Das, Siddhartha

Ball grid arrays (BGA) are interconnects between an integrated circuit (IC) and a printed circuit board (PCB), that are used for surface mounting electronic components. Typically, lead free alloys are used to make solder balls which, after a reflow process, establish a mechanical and electrical connection between the IC and the PCB. High temperature processing is required for most of these alloys leading to thermal shock causing damage to ICs. For producing flexible circuits on a polymer substrate, there is a requirement for low temperature processing capabilities (around 150 C) and for reducing strain from mechanical stresses. Additive manufacturing techniques can provide an alternative methodology for fabricating BGAs as a direct replacement for standard solder bumped BGAs. We have developed aerosol jet (AJ) printing methods to fabricate a polymer bumped BGA. As a demonstration of the process developed, a daisy chain test chip was polymer bumped using an AJ printed ultra violet (UV) curable polymer ink that was then coated with an AJ printed silver nanoparticle laden ink as a conducting layer printed over the polymer bump. The structure for the balls were achieved by printing the polymer ink using a specific toolpath coupled with in-situ UV curing of the polymer which provided good control over the shape, resulting in well-formed spherical bumps on the order of 200 um wide by 200 um tall for this initial demonstration. A detailed discussion of the AJ printing method and results from accelerated life-time testing will be presented

The BUMP model of response planning: intermittent predictive control accounts for 10 Hz physiological tremor.

PubMed

Bye, Robin T; Neilson, Peter D

2010-10-01

Physiological tremor during movement is characterized by ∼10 Hz oscillation observed both in the electromyogram activity and in the velocity profile. We propose that this particular rhythm occurs as the direct consequence of a movement response planning system that acts as an intermittent predictive controller operating at discrete intervals of ∼100 ms. The BUMP model of response planning describes such a system. It forms the kernel of Adaptive Model Theory which defines, in computational terms, a basic unit of motor production or BUMP. Each BUMP consists of three processes: (1) analyzing sensory information, (2) planning a desired optimal response, and (3) execution of that response. These processes operate in parallel across successive sequential BUMPs. The response planning process requires a discrete-time interval in which to generate a minimum acceleration trajectory to connect the actual response with the predicted future state of the target and compensate for executional error. We have shown previously that a response planning time of 100 ms accounts for the intermittency observed experimentally in visual tracking studies and for the psychological refractory period observed in double stimulation reaction time studies. We have also shown that simulations of aimed movement, using this same planning interval, reproduce experimentally observed speed-accuracy tradeoffs and movement velocity profiles. Here we show, by means of a simulation study of constant velocity tracking movements, that employing a 100 ms planning interval closely reproduces the measurement discontinuities and power spectra of electromyograms, joint-angles, and angular velocities of physiological tremor reported experimentally. We conclude that intermittent predictive control through sequential operation of BUMPs is a fundamental mechanism of 10 Hz physiological tremor in movement. Copyright © 2010 Elsevier B.V. All rights reserved.

Review of the development of diamond radiation sensors

NASA Astrophysics Data System (ADS)

Adam, W.; Bauer, C.; Berdermann, E.; Bergonzo, P.; Bogani, F.; Borchi, E.; Brambilla, A.; Bruzzi, M.; Colledani, C.; Conway, J.; Dabrowski, W.; Delpierre, P.; Deneuville, A.; Dulinski, W.; van Eijk, B.; Fallou, A.; Fizzotti, F.; Foulon, F.; Friedl, M.; Gan, K. K.; Gheeraert, E.; Grigoriev, E.; Hallewell, G.; Hall-Wilton, R.; Han, S.; Hartjes, F.; Hrubec, J.; Husson, D.; Kagan, H.; Kania, D.; Kaplon, J.; Karl, C.; Kass, R.; Knöpfle, K. T.; Krammer, M.; Logiudice, A.; Lu, R.; Manfredi, P. F.; Manfredotti, C.; Marshall, R. D.; Meier, D.; Mishina, M.; Oh, A.; Pan, L. S.; Palmieri, V. G.; Pernicka, M.; Peitz, A.; Pirollo, S.; Polesello, P.; Pretzl, K.; Re, V.; Riester, J. L.; Roe, S.; Roff, D.; Rudge, A.; Schnetzer, S.; Sciortino, S.; Speziali, V.; Stelzer, H.; Stone, R.; Tapper, R. J.; Tesarek, R.; Thomson, G. B.; Trawick, M.; Trischuk, W.; Vittone, E.; Walsh, A. M.; Wedenig, R.; Weilhammer, P.; Ziock, H.; Zoeller, M.; RD42 Collaboration

1999-09-01

Diamond radiation sensors produced by chemical vapour deposition are studied for the application as tracking detectors in high luminosity experiments. Sensors with a charge collection distance up to 250 μm have been manufactured. Their radiation hardness has been studied with pions, proton and neutrons up to fluences of 1.9×10 15 π cm -2, 5×10 15 p cm -2 and 1.35×10 15 n cm -2, respectively. Diamond micro-strip detectors with 50 μm pitch have been exposed in a high-energy test beam in order to investigate their charge collection properties. The measured spatial resolution using a centre-of-gravity position finding algorithm corresponds to the digital resolution for this strip pitch. First results from a strip tracker with a 2×4 cm 2 surface area are reported as well as the performance of a diamond tracker read out by radiation-hard electronics with 25 ns shaping time. Diamond pixel sensors have been prepared to match the geometries of the recently available read-out chip prototypes for ATLAS and CMS. Beam test results are shown from a diamond detector bump-bonded to an ATLAS prototype read-out. They demonstrate a 98% bump-bonding efficiency and a digital resolution in both dimensions.

The Red-giant Branch Bump Revisited: Constraints on Envelope Overshooting in a Wide Range of Masses and Metallicities

NASA Astrophysics Data System (ADS)

Khan, Saniya; Hall, Oliver J.; Miglio, Andrea; Davies, Guy R.; Mosser, Benoît; Girardi, Léo; Montalbán, Josefina

2018-06-01

The red-giant branch bump provides valuable information for the investigation of the internal structure of low-mass stars. Because current models are unable to accurately predict the occurrence and efficiency of mixing processes beyond convective boundaries, one can use the luminosity of the bump—a diagnostic of the maximum extension of the convective envelope during the first-dredge up—as a calibrator for such processes. By combining asteroseismic and spectroscopic constraints, we expand the analysis of the bump to masses and metallicities beyond those previously accessible using globular clusters. Our data set comprises nearly 3000 red-giant stars observed by Kepler and with APOGEE spectra. Using statistical mixture models, we are able to detect the bump in the average seismic parameters ν max and < {{Δ }}ν > , and show that its observed position reveals general trends with mass and metallicity in line with expectations from models. Moreover, our analysis indicates that standard stellar models underestimate the depth of efficiently mixed envelopes. The inclusion of significant overshooting from the base of the convective envelope, with an efficiency that increases with decreasing metallicity, allows us to reproduce the observed location of the bump. Interestingly, this trend was also reported in previous studies of globular clusters.

Integrated readout electronics for Belle II pixel detector

NASA Astrophysics Data System (ADS)

Blanco, R.; Leys, R.; Perić, I.

2018-03-01

This paper describes the readout components for Belle II that have been designed as integrated circuits. The ICs are connected to DEPFET sensor by bump bonding. Three types of ICs have been developed: SWITCHER for pixel matrix control, DCD for readout and digitizing of sensor signals and DHP for digital data processing. The ICs are radiation tolerant and use several novel features, such as the multiple-input differential amplifiers and the fast and radiation hard high-voltage drivers. SWITCHER and DCD have been developed at University of Heidelberg, Karlsruhe Institute of Technology (KIT) and DHP at Bonn University. The IC-development started in 2009 and was accomplished in 2016 with the submissions of final designs. The final ICs for Belle II pixel detector and the related measurement results will be presented in this contribution.

Wafer-Level Hermetic Package by Low-Temperature Cu/Sn TLP Bonding with Optimized Sn Thickness

NASA Astrophysics Data System (ADS)

Wu, Zijian; Cai, Jian; Wang, Qian; Wang, Junqiang; Wang, Dejun

2017-10-01

In this paper, a wafer-level package with hermetic sealing by low-temperature Cu/Sn transient liquid phase (TLP) bonding for a micro-electromechanical system was introduced. A Cu bump with a Sn cap and sealing ring were fabricated simultaneously by electroplating. The model of Cu/Sn TLP bonding was established and the thicknesses of Cu and Sn were optimized after a series of bonding experiments. Cu/Sn wafer-level bonding was undertaken at 260°C for 30 min under a vacuum condition. An average shear strength of 50.36 MPa and a fine leak rate of 1.9 × 10-8 atm cc/s were achieved. Scanning electron microscope photos of the Cu/Sn/Cu interlayers were presented, and energy dispersive x-ray analysis was conducted simultaneously. The results showed that the Sn was completely consumed to form the stable intermetallic compound Cu3Sn. An aging test of 200 h at 200°C was conducted to test the performance of the hermetic sealing, while the results of shear strength, fine leak rate and bonding interface were also set out.

Thin hybrid pixel assembly with backside compensation layer on ROIC

NASA Astrophysics Data System (ADS)

Bates, R.; Buttar, C.; McMullen, T.; Cunningham, L.; Ashby, J.; Doherty, F.; Gray, C.; Pares, G.; Vignoud, L.; Kholti, B.; Vahanen, S.

2017-01-01

The entire ATLAS inner tracking system will be replaced for operation at the HL-LHC . This will include a significantly larger pixel detector of approximately 15 m2. For this project, it is critical to reduce the mass of the hybrid pixel modules and this requires thinning both the sensor and readout chips to about 150 micrometres each. The thinning of the silicon chips leads to low bump yield for SnAg bumps due to bad co-planarity of the two chips at the solder reflow stage creating dead zones within the pixel array. In the case of the ATLAS FEI4 pixel readout chip thinned to 100 micrometres, the chip is concave, with the front side in compression, with a bow of +100 micrometres at room temperature which varies to a bow of -175 micrometres at the SnAg solder reflow temperature, caused by the CTE mismatch between the materials in the CMOS stack and the silicon substrate. A new wafer level process to address the issue of low bump yield be controlling the chip bow has been developed. A back-side dielectric and metal stack of SiN and Al:Si has been deposited on the readout chip wafer to dynamically compensate the stress of the front side stack. In keeping with a 3D process the materials used are compatible with Through Silicon Via (TSV) technology with a TSV last approach which is under development for this chip. It is demonstrated that the amplitude of the correction can be manipulated by the deposition conditions and thickness of the SiN/Al:Si stack. The bow magnitude over the temperature range for the best sample to date is reduced by almost a factor of 4 and the sign of the bow (shape of the die) remains constant. Further development of the backside deposition conditions is on-going with the target of close to zero bow at the solder reflow temperature and a minimal bow magnitude throughout the temperature range. Assemblies produced from FEI4 readout wafers thinned to 100 micrometres with the backside compensation layer have been made for the first time and demonstrate bond yields close to 100%.

Detection of micro solder balls using active thermography and probabilistic neural network

NASA Astrophysics Data System (ADS)

He, Zhenzhi; Wei, Li; Shao, Minghui; Lu, Xingning

2017-03-01

Micro solder ball/bump has been widely used in electronic packaging. It has been challenging to inspect these structures as the solder balls/bumps are often embedded between the component and substrates, especially in flip-chip packaging. In this paper, a detection method for micro solder ball/bump based on the active thermography and the probabilistic neural network is investigated. A VH680 infrared imager is used to capture the thermal image of the test vehicle, SFA10 packages. The temperature curves are processed using moving average technique to remove the peak noise. And the principal component analysis (PCA) is adopted to reconstruct the thermal images. The missed solder balls can be recognized explicitly in the second principal component image. Probabilistic neural network (PNN) is then established to identify the defective bump intelligently. The hot spots corresponding to the solder balls are segmented from the PCA reconstructed image, and statistic parameters are calculated. To characterize the thermal properties of solder bump quantitatively, three representative features are selected and used as the input vector in PNN clustering. The results show that the actual outputs and the expected outputs are consistent in identification of the missed solder balls, and all the bumps were recognized accurately, which demonstrates the viability of the PNN in effective defect inspection in high-density microelectronic packaging.

Ultraviolet photometry from the Orbiting Astronomical Observatory. XX - The ultraviolet extinction bump

NASA Technical Reports Server (NTRS)

Savage, B. D.

1975-01-01

Ultraviolet extinction bumps are investigated in the interstellar extinction curves between 1800 and 3600 A for 36 stars which have (B-V) excesses ranging from 0.03 to 0.55 and are mostly confined to the brighter OB associations distributed along the galactic plane. Each extinction curve is found to have a broad bump which peaks near 2175 A and whose position and profile appear to be constant among all the stars. It is shown that the bump is probably interstellar in origin and that the constancy of its position and shape places such severe restrictions on grain geometrical parameters that classical scattering theory cannot be used to explain the feature unless the dust grains in widely separated regions of space and with very different physical conditions are assumed to have nearly identical size and shape distributions. Three extinction curves which extend to 1100 A are examined and found to have the same general characteristics as the others. Several extinction curves are analyzed for fine structure, but no convincing evidence is found in the present interval. Some processes are discussed which may be responsible for the bumps.

Defect Inspection of Flip Chip Solder Bumps Using an Ultrasonic Transducer

PubMed Central

Su, Lei; Shi, Tielin; Xu, Zhensong; Lu, Xiangning; Liao, Guanglan

2013-01-01

Surface mount technology has spurred a rapid decrease in the size of electronic packages, where solder bump inspection of surface mount packages is crucial in the electronics manufacturing industry. In this study we demonstrate the feasibility of using a 230 MHz ultrasonic transducer for nondestructive flip chip testing. The reflected time domain signal was captured when the transducer scanning the flip chip, and the image of the flip chip was generated by scanning acoustic microscopy. Normalized cross-correlation was used to locate the center of solder bumps for segmenting the flip chip image. Then five features were extracted from the signals and images. The support vector machine was adopted to process the five features for classification and recognition. The results show the feasibility of this approach with high recognition rate, proving that defect inspection of flip chip solder bumps using the ultrasonic transducer has high potential in microelectronics packaging.

Three dimensional, multi-chip module

DOEpatents

Bernhardt, A.F.; Petersen, R.W.

1993-08-31

A plurality of multi-chip modules are stacked and bonded around the perimeter by sold-bump bonds to adjacent modules on, for instance, three sides of the perimeter. The fourth side can be used for coolant distribution, for more interconnect structures, or other features, depending on particular design considerations of the chip set. The multi-chip modules comprise a circuit board, having a planarized interconnect structure formed on a first major surface, and integrated circuit chips bonded to the planarized interconnect surface. Around the periphery of each circuit board, long, narrow dummy chips'' are bonded to the finished circuit board to form a perimeter wall. The wall is higher than any of the chips on the circuit board, so that the flat back surface of the board above will only touch the perimeter wall. Module-to-module interconnect is laser-patterned on the sides of the boards and over the perimeter wall in the same way and at the same time that chip to board interconnect may be laser-patterned.

Three dimensional, multi-chip module

DOEpatents

Bernhardt, Anthony F.; Petersen, Robert W.

1993-01-01

A plurality of multi-chip modules are stacked and bonded around the perimeter by sold-bump bonds to adjacent modules on, for instance, three sides of the perimeter. The fourth side can be used for coolant distribution, for more interconnect structures, or other features, depending on particular design considerations of the chip set. The multi-chip modules comprise a circuit board, having a planarized interconnect structure formed on a first major surface, and integrated circuit chips bonded to the planarized interconnect surface. Around the periphery of each circuit board, long, narrow "dummy chips" are bonded to the finished circuit board to form a perimeter wall. The wall is higher than any of the chips on the circuit board, so that the flat back surface of the board above will only touch the perimeter wall. Module-to-module interconnect is laser-patterned o the sides of the boards and over the perimeter wall in the same way and at the same time that chip to board interconnect may be laser-patterned.

Effects of structural and chemical disorders on the vis/UV spectra of carbonaceous interstellar grains

NASA Astrophysics Data System (ADS)

Papoular, Robert J.; Yuan, Shengjun; Roldán, Rafael; Katsnelson, Mikhail I.; Papoular, Renaud

2013-07-01

The recent spectacular progress in the experimental and theoretical understanding of graphene, the basic constituent of graphite, is applied here to compute, from first principles, the ultraviolet extinction of nanoparticles made of stacks of graphene layers. The theory also covers cases where graphene is affected by structural, chemical or orientation disorder, each disorder type being quantitatively defined by a single parameter. The extinction bumps carried by such model materials are found to have positions and widths falling in the same range as the known astronomical 2175 Å features: as the disorder parameter increases, the bump width increases from 0.85 to 2.5 μm-1, while its peak position shifts from 4.65 to 4.75 μm-1. Moderate degrees of disorder are enough to cover the range of widths of the vast majority of observed bumps (0.75 to 1.3 μm-1). Higher degrees account for outliers, also observed in the sky. The introduction of structural or chemical disorder amounts to changing the initial sp2 bondings into sp3 or sp1, so the optical properties of the model material become similar to those of the more or less amorphous carbon-rich materials studied in the laboratory: a-C, a-C:H, HAC, ACH, coals, etc. The present treatment thus bridges gaps between physically different model materials.

PbS-PbSe IR detector arrays

NASA Technical Reports Server (NTRS)

Barrett, John R. (Inventor)

1986-01-01

A silicon wafer is provided which does not employ individually bonded leads between the IR sensitive elements and the input stages of multiplexers. The wafer is first coated with lead selenide in a first detector array area and is thereafter coated with lead sulfide within a second detector array area. The described steps result in the direct chemical deposition of lead selenide and lead sulfide upon the silicon wafer to eliminate individual wire bonding, bumping, flip chipping, planar interconnecting methods of connecting detector array elements to silicon chip circuitry, e.g., multiplexers, to enable easy fabrication of very long arrays. The electrode structure employed, produces an increase in the electrical field gradient between the electrodes for a given volume of detector material, relative to conventional electrode configurations.

Photogrammetric 3d Acquisition and Analysis of Medicamentous Induced Pilomotor Reflex ("goose Bumps")

NASA Astrophysics Data System (ADS)

Schneider, D.; Hecht, A.

2016-06-01

In a current study at the University Hospital Dresden, Department of Neurology, the autonomous function of nerve fibres of the human skin is investigated. For this purpose, a specific medicament is applied on a small area of the skin of a test person which results in a local reaction (goose bumps). Based on the extent of the area, where the stimulation of the nerve fibres is visible, it can be concluded how the nerve function of the skin works. The aim of the investigation described in the paper is to generate 3D data of these goose bumps. Therefore, the paper analyses and compares different photogrammetric surface measurement techniques in regard to their suitability for the 3D acquisition of silicone imprints of the human skin. Furthermore, an appropriate processing procedure for analysing the recorded point cloud data is developed and presented. It was experimentally proven that by using (low-cost) photogrammetric techniques medicamentous induced goose bumps can be acquired in three dimensions and can be analysed almost fully automatically from the perspective of medical research questions. The relative accuracy was determined with 1% (RMSE) of the area resp. the volume of an individual goose bump.

Ultra-fast Movies Resolve Ultra-short Pulse Laser Ablation and Bump Formation on Thin Molybdenum Films

NASA Astrophysics Data System (ADS)

Domke, Matthias; Rapp, Stephan; Huber, Heinz

For the monolithic serial interconnection of CIS thin film solar cells, 470 nm molybdenum films on glass substrates must be separated galvanically. The single pulse ablation with a 660 fs laser at a wavelength of 1053 nm is investigated in a fluence regime from 0.5 to 5.0 J/cm2. At fluences above 2.0 J/cm2 bump and jet formation can be observed that could be used for creating microstructures. For the investigation of the underlying mechanisms of the laser ablation process itself as well as of the bump or jet formation, pump probe microscopy is utilized to resolve the transient ablation behavior.

The 1600 Å Emission Bump in Protoplanetary Disks: A Spectral Signature of H{sub 2}O Dissociation

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

France, Kevin; Roueff, Evelyne; Abgrall, Hervé, E-mail: kevin.france@colorado.edu

The FUV continuum spectrum of many accreting pre-main sequence stars, Classical T Tauri Stars (CTTSs), does not continue smoothly from the well-studied Balmer continuum emission in the NUV, suggesting that additional processes contribute to the short-wavelength emission in these objects. The most notable spectral feature in the FUV continuum of some CTTSs is a broad emission approximately centered at 1600 Å, which has been referred to as the “1600 Å Bump.” The origin of this feature remains unclear. In an effort to better understand the molecular properties of planet-forming disks and the UV spectral properties of accreting protostars, we havemore » assembled archival FUV spectra of 37 disk-hosting systems observed by the Hubble Space Telescope -Cosmic Origins Spectrograph. Clear 1600 Å Bump emission is observed above the smooth, underlying 1100–1800 Å continuum spectrum in 19/37 Classical T Tauri disks in the HST -COS sample, with the detection rate in transition disks (8/8) being much higher than that in primordial or non-transition sources (11/29). We describe a spectral deconvolution analysis to separate the Bump (spanning 1490–1690 Å) from the underlying FUV continuum, finding an average Bump luminosity L (Bump) ≈ 7 × 10{sup 29} erg s{sup −1}. Parameterizing the Bump with a combination of Gaussian and polynomial components, we find that the 1600 Å Bump is characterized by a peak wavelength λ {sub o} = 1598.6 ± 3.3 Å, with FWHM = 35.8 ± 19.1 Å. Contrary to previous studies, we find that this feature is inconsistent with models of H{sub 2} excited by electron -impact. We show that this Bump makes up between 5%–50% of the total FUV continuum emission in the 1490–1690 Å band and emits roughly 10%–80% of the total fluorescent H{sub 2} luminosity for stars with well-defined Bump features. Energetically, this suggests that the carrier of the 1600 Å Bump emission is powered by Ly α photons. We argue that the most likely mechanism is Ly α -driven dissociation of H{sub 2}O in the inner disk, r ≲ 2 au. We demonstrate that non-thermally populated H{sub 2}O fragments can qualitatively account for the observed emission (discrete and continuum) and find that the average Ly α -driven H{sub 2}O dissociation rate is 1.7 × 10{sup 42} water molecules s{sup −1}.« less

Aqueous-based thick photoresist removal for bumping applications

NASA Astrophysics Data System (ADS)

Moore, John C.; Brewer, Alex J.; Law, Alman; Pettit, Jared M.

2015-03-01

Cleaning processes account for over 25% of processing in microelectronic manufacturing [1], suggesting electronics to be one of the most chemical intensive markets in commerce. Industry roadmaps exist to reduce chemical exposure, usage, and waste [2]. Companies are encouraged to create a safer working environment, or green factory, and ultimately become certified similar to LEED in the building industry [3]. A significant step in this direction is the integration of aqueous-based photoresist (PR) strippers which eliminate regulatory risks and cut costs by over 50%. One of the largest organic solvent usages is based upon thick PR removal during bumping processes [4-6]. Using market projections and the benefits of recycling, it is estimated that over 1,000 metric tons (mt) of residuals originating from bumping processes are incinerated or sent to a landfill. Aqueous-based stripping would eliminate this disposal while also reducing the daily risks to workers and added permitting costs. Positive-tone PR dissolves in aqueous strippers while negative-tone systems are lifted-off from the substrate, bumps, pillars, and redistribution layers (RDL). While the wafers are further processed and rinsed, the lifted-off PR is pumped from the tank, collected onto a filter, and periodically back-flushed to the trash. The PR solids become a non-hazardous plastic waste while the liquids are mixed with the developer stream, neutralized, filtered, and in most cases, disposed to the sewer. Regardless of PR thickness, removal processes may be tuned to perform in <15min, performing at rates nearly 10X faster than solvents with higher bath lives. A balanced formula is safe for metals, dielectrics, and may be customized to any fab.

Wafer-Level Membrane-Transfer Process for Fabricating MEMS

NASA Technical Reports Server (NTRS)

Yang, Eui-Hyeok; Wiberg, Dean

2003-01-01

A process for transferring an entire wafer-level micromachined silicon structure for mating with and bonding to another such structure has been devised. This process is intended especially for use in wafer-level integration of microelectromechanical systems (MEMS) that have been fabricated on dissimilar substrates. Unlike in some older membrane-transfer processes, there is no use of wax or epoxy during transfer. In this process, the substrate of a wafer-level structure to be transferred serves as a carrier, and is etched away once the transfer has been completed. Another important feature of this process is that two electrodes constitutes an electrostatic actuator array. An SOI wafer and a silicon wafer (see Figure 1) are used as the carrier and electrode wafers, respectively. After oxidation, both wafers are patterned and etched to define a corrugation profile and electrode array, respectively. The polysilicon layer is deposited on the SOI wafer. The carrier wafer is bonded to the electrode wafer by using evaporated indium bumps. The piston pressure of 4 kPa is applied at 156 C in a vacuum chamber to provide hermetic sealing. The substrate of the SOI wafer is etched in a 25 weight percent TMAH bath at 80 C. The exposed buried oxide is then removed by using 49 percent HF droplets after an oxygen plasma ashing. The SOI top silicon layer is etched away by using an SF6 plasma to define the corrugation profile, followed by the HF droplet etching of the remaining oxide. The SF6 plasma with a shadow mask selectively etches the polysilicon membrane, if the transferred membrane structure needs to be patterned. Electrostatic actuators with various electrode gaps have been fabricated by this transfer technique. The gap between the transferred membrane and electrode substrate is very uniform ( 0.1 m across a wafer diameter of 100 mm, provided by optimizing the bonding control). Figure 2 depicts the finished product.

Foil Gas Thrust Bearings for High-Speed Turbomachinery

NASA Technical Reports Server (NTRS)

Edmonds, Brian; DellaCorte, Christopher; Dykas, Brian

2010-01-01

A methodology has been developed for the design and construction of simple foil thrust bearings intended for parametric performance testing and low marginal costs, supporting continued development of oil-free turbomachinery. A bearing backing plate is first machined and surface-ground to produce flat and parallel faces. Partial-arc slots needed to retain the foil components are then machined into the plate by wire electrical discharge machining. Slot thicknesses achievable by a single wire pass are appropriate to accommodate the practical range of foil thicknesses, leaving a small clearance in this hinged joint to permit limited motion. The backing plate is constructed from a nickel-based superalloy (Inconel 718) to allow heat treatment of the entire assembled bearing, as well as to permit hightemperature operation. However, other dimensionally stable materials, such as precipitation-hardened stainless steel, can also be used for this component depending on application. The top and bump foil blanks are cut from stacks of annealed Inconel X-750 foil by the same EDM process. The bump foil has several azimuthal slits separating it into five individual bump strips. This configuration allows for variable bump spacing, which helps to accommodate the effects of the varying surface velocity, thermal crowning, centrifugal dishing, and misalignment. Rectangular tabs on the foil blanks fit into the backing plate slots. For this application, a rather traditional set of conventionally machined dies is selected, and bump foil blanks are pressed into the dies for forming. This arrangement produces a set of bump foil dies for foil thrust bearings that provide for relatively inexpensive fabrication of various bump configurations, and employing methods and features from the public domain.

Silicon Hard-Stop Mesas for 3D Integration of Superconducting Qubits

NASA Astrophysics Data System (ADS)

Kim, David; Rosenberg, Danna; Osadchy, Brenda; Calusine, Greg; Das, Rabindra; Melville, Alexander; Yoder, Jonilyn; Yost, Donna-Ruth; Racz, Livia; Oliver, William

As quantum computing with superconducting qubits advances past the few-qubit stage, implementing 3D packaging/integration to route readout/control lines will become increasingly important. One approach is to bond chips that perform different functions using indium bump bonds. Because indium is malleable, however, achieving the desired spacing and tilt between two chips can be challenging. We present an approach based on etching several microns into the silicon substrate to produce hard stop silicon posts. Since this process involves etching into a pristine substrate, it is essential to evaluate its impact on qubit performance. We report the etched surface's effect on the resonator quality factor and qubit coherence time, as well as the improvement in planarity and tilt. This research was funded in part by the Office of the Director of National Intelligence (ODNI), Intelligence Advanced Research Projects Activity (IARPA) and by the Assistant Secretary of Defense for Research & Engineering under Air Force Contract No. FA8721-05-C-0002. The views and conclusions contained herein are those of the authors and should not be interpreted as necessarily representing the official policies or endorsements, either expressed or implied, of ODNI, IARPA, or the US Government.

Warpage Characteristics and Process Development of Through Silicon Via-Less Interconnection Technology.

PubMed

Shen, Wen-Wei; Lin, Yu-Min; Wu, Sheng-Tsai; Lee, Chia-Hsin; Huang, Shin-Yi; Chang, Hsiang-Hung; Chang, Tao-Chih; Chen, Kuan-Neng

2018-08-01

In this study, through silicon via (TSV)-less interconnection using the fan-out wafer-level-packaging (FO-WLP) technology and a novel redistribution layer (RDL)-first wafer level packaging are investigated. Since warpage of molded wafer is a critical issue and needs to be optimized for process integration, the evaluation of the warpage issue on a 12-inch wafer using finite element analysis (FEA) at various parameters is presented. Related parameters include geometric dimension (such as chip size, chip number, chip thickness, and mold thickness), materials' selection and structure optimization. The effect of glass carriers with various coefficients of thermal expansion (CTE) is also discussed. Chips are bonded onto a 12-inch reconstituted wafer, which includes 2 RDL layers, 3 passivation layers, and micro bumps, followed by using epoxy molding compound process. Furthermore, an optical surface inspector is adopted to measure the surface profile and the results are compared with the results from simulation. In order to examine the quality of the TSV-less interconnection structure, electrical measurement is conducted and the respective results are presented.

3D Stacked Memory Final Report CRADA No. TC-0494-93

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

Bernhardt, A.; Beene, G.

TI and LLNL demonstrated: (1) a process for the fabrication of 3-D memory using stacked DRAM chips, and (2) a fast prototyping process for 3-D stacks and MCMs. The metallization to route the chip pads to the sides of the die was carried out in a single high-speed masking step. The mask was not the usual physical one in glass and chrome, but was simply a computer file used to control the laser patterning process. Changes in either chip or customer circuit-board pad layout were easily and inexpensively accommodated, so that prototyping was a natural consequence of the laser patterningmore » process. As in the current TI process, a dielectric layer was added to the wafer, and vias to the chip I/0 pads were formed. All of the steps in Texas Instruments earlier process that were required to gold bump the pads were eliminated, significantly reducing fabrication cost and complexity. Pads were created on the sides of ·the die, which became pads on the side of the stack. In order to extend the process to accommodate non-memory devices with substantially greater I/0 than is required for DRAMs, pads were patterned on two sides of the memory stacks as a proof of principle. Stacking and bonding were done using modifications of the current TI process. After stacking and bonding, the pads on the sides of the dice were connected by application of a polyimide insulator film with laser ablation of the polyimide to form contacts to the pads. Then metallization was accomplished in the same manner as on the individual die.« less

Extended-spectrum antiprotozoal bumped kinase inhibitors: A review.

PubMed

Van Voorhis, Wesley C; Doggett, J Stone; Parsons, Marilyn; Hulverson, Matthew A; Choi, Ryan; Arnold, Samuel L M; Riggs, Michael W; Hemphill, Andrew; Howe, Daniel K; Mealey, Robert H; Lau, Audrey O T; Merritt, Ethan A; Maly, Dustin J; Fan, Erkang; Ojo, Kayode K

2017-09-01

Many life-cycle processes in parasites are regulated by protein phosphorylation. Hence, disruption of essential protein kinase function has been explored for therapy of parasitic diseases. However, the difficulty of inhibiting parasite protein kinases to the exclusion of host orthologues poses a practical challenge. A possible path around this difficulty is the use of bumped kinase inhibitors for targeting calcium-dependent protein kinases that contain atypically small gatekeeper residues and are crucial for pathogenic apicomplexan parasites' survival and proliferation. In this article, we review efficacy against the kinase target, parasite growth in vitro, and in animal infection models, as well as the relevant pharmacokinetic and safety parameters of bumped kinase inhibitors. Copyright © 2017 Elsevier Inc. All rights reserved.

Nanofiber Anisotropic Conductive Films (ACF) for Ultra-Fine-Pitch Chip-on-Glass (COG) Interconnections

NASA Astrophysics Data System (ADS)

Lee, Sang-Hoon; Kim, Tae-Wan; Suk, Kyung-Lim; Paik, Kyung-Wook

2015-11-01

Nanofiber anisotropic conductive films (ACF) were invented, by adapting nanofiber technology to ACF materials, to overcome the limitations of ultra-fine-pitch interconnection packaging, i.e. shorts and open circuits as a result of the narrow space between bumps and electrodes. For nanofiber ACF, poly(vinylidene fluoride) (PVDF) and poly(butylene succinate) (PBS) polymers were used as nanofiber polymer materials. For PVDF and PBS nanofiber ACF, conductive particles of diameter 3.5 μm were incorporated into nanofibers by electrospinning. In ultra-fine-pitch chip-on-glass assembly, insulation was significantly improved by using nanofiber ACF, because nanofibers inside the ACF suppressed the mobility of conductive particles, preventing them from flowing out during the bonding process. Capture of conductive particles was increased from 31% (conventional ACF) to 65%, and stable electrical properties and reliability were achieved by use of nanofiber ACF.

Flip chip bumping technology—Status and update

NASA Astrophysics Data System (ADS)

Juergen Wolf, M.; Engelmann, Gunter; Dietrich, Lothar; Reichl, Herbert

2006-09-01

Flip chip technology is a key driver for new complex system architectures and high-density packaging, e.g. sensor or pixel devices. Bumped wafers/dice as key elements become very important in terms of general availability at low cost, high yield and quality level. Today, different materials, e.g. Au, Ni, AuSn, SnAg, SnAgCu, SnCu, etc., are used for flip chip interconnects and different bumping approaches are available. Electroplating is the technology of choice for high-yield wafer bumping for small bump sizes and pitches. Lead-free solder bumps require an increase in knowledge in the field of under bump metallization (UBM) and the interaction of bump and substrate metallization, the formation and growth of intermetallic compounds (IMCs) during liquid- and solid-phase reactions. Results of a new bi-layer UBM of Ni-Cu which is especially designed for small-sized lead-free solder bumps will be discussed.

The reminiscence bump in autobiographical memory and for public events: A comparison across different cueing methods.

PubMed

Koppel, Jonathan; Berntsen, Dorthe

2016-01-01

The reminiscence bump has been found for both autobiographical memories and memories of public events. However, there have been few comparisons of the bump across each type of event. In the current study, therefore, we compared the bump for autobiographical memories versus the bump for memories of public events. We did so between-subjects, through two cueing methods administered within-subjects, the cue word method and the important memories method. For word-cued memories, we found a similar bump from ages 5 to 19 for both types of memories. However, the bump was more pronounced for autobiographical memories. For most important memories, we found a bump from ages 20 to 29 in autobiographical memory, but little discernible age pattern for public events. Rather, specific public events (e.g., the Fall of the Berlin Wall) dominated recall, producing a chronological distribution characterised by spikes in citations according to the years these events occurred. Follow-up analyses suggested that the bump in most important autobiographical memories was a function of the cultural life script. Our findings did not yield support for any of the dominant existing accounts of the bump as underlying the bump in word-cued memories.

Method of fabricating a PbS-PbSe IR detector array

NASA Technical Reports Server (NTRS)

Barrett, John R. (Inventor)

1987-01-01

A silicon wafer is provided which does not employ individually bonded leads between the IR sensitive elements and the input stages of multiplexers. The wafer is first coated with lead selenide in a first detector array area and is thereafter coated with lead sulfide within a second detector array area. The described steps result in the direct chemical deposition of lead selenide and lead sulfide upon the silicon wafer to eliminate individual wire bonding, bumping, flip chiping, planar interconnecting methods of connecting detector array elements to silicon chip circuitry, e.g., multiplexers, to enable easy fabrication of very long arrays. The electrode structure employed, produces an increase in the electrical field gradient between the electrodes for a given volume of detector material, relative to conventional electrode configurations.

The 1600 Å Emission Bump in Protoplanetary Disks: A Spectral Signature of H2O Dissociation

NASA Astrophysics Data System (ADS)

France, Kevin; Roueff, Evelyne; Abgrall, Hervé

2017-08-01

The FUV continuum spectrum of many accreting pre-main sequence stars, Classical T Tauri Stars (CTTSs), does not continue smoothly from the well-studied Balmer continuum emission in the NUV, suggesting that additional processes contribute to the short-wavelength emission in these objects. The most notable spectral feature in the FUV continuum of some CTTSs is a broad emission approximately centered at 1600 Å, which has been referred to as the “1600 Å Bump.” The origin of this feature remains unclear. In an effort to better understand the molecular properties of planet-forming disks and the UV spectral properties of accreting protostars, we have assembled archival FUV spectra of 37 disk-hosting systems observed by the Hubble Space Telescope-Cosmic Origins Spectrograph. Clear 1600 Å Bump emission is observed above the smooth, underlying 1100-1800 Å continuum spectrum in 19/37 Classical T Tauri disks in the HST-COS sample, with the detection rate in transition disks (8/8) being much higher than that in primordial or non-transition sources (11/29). We describe a spectral deconvolution analysis to separate the Bump (spanning 1490-1690 Å) from the underlying FUV continuum, finding an average Bump luminosity L(Bump) ≈ 7 × 1029 erg s-1. Parameterizing the Bump with a combination of Gaussian and polynomial components, we find that the 1600 Å Bump is characterized by a peak wavelength λ o = 1598.6 ± 3.3 Å, with FWHM = 35.8 ± 19.1 Å. Contrary to previous studies, we find that this feature is inconsistent with models of H2 excited by electron -impact. We show that this Bump makes up between 5%-50% of the total FUV continuum emission in the 1490-1690 Å band and emits roughly 10%-80% of the total fluorescent H2 luminosity for stars with well-defined Bump features. Energetically, this suggests that the carrier of the 1600 Å Bump emission is powered by Lyα photons. We argue that the most likely mechanism is Lyα-driven dissociation of H2O in the inner disk, r ≲ 2 au. We demonstrate that non-thermally populated H2O fragments can qualitatively account for the observed emission (discrete and continuum) and find that the average Lyα-driven H2O dissociation rate is 1.7 × 1042 water molecules s-1. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the data archive at the Space Telescope Science Institute. STScI is operated by the Association of Universities for Research in Astronomy, Inc. under NASA contract NAS 5-26555.

Single bumps in a 2-population homogenized neuronal network model

NASA Astrophysics Data System (ADS)

Kolodina, Karina; Oleynik, Anna; Wyller, John

2018-05-01

We investigate existence and stability of single bumps in a homogenized 2-population neural field model, when the firing rate functions are given by the Heaviside function. The model is derived by means of the two-scale convergence technique of Nguetseng in the case of periodic microvariation in the connectivity functions. The connectivity functions are periodically modulated in both the synaptic footprint and in the spatial scale. The bump solutions are constructed by using a pinning function technique for the case where the solutions are independent of the local variable. In the weakly modulated case the generic picture consists of two bumps (one narrow and one broad bump) for each admissible set of threshold values for firing. In addition, a new threshold value regime for existence of bumps is detected. Beyond the weakly modulated regime the number of bumps depends sensitively on the degree of heterogeneity. For the latter case we present a configuration consisting of three coexisting bumps. The linear stability of the bumps is studied by means of the spectral properties of a Fredholm integral operator, block diagonalization of this operator and the Fourier decomposition method. In the weakly modulated regime, one of the bumps is unstable for all relative inhibition times, while the other one is stable for small and moderate values of this parameter. The latter bump becomes unstable as the relative inhibition time exceeds a certain threshold. In the case of the three coexisting bumps detected in the regime of finite degree of heterogeneity, we have at least one stable bump (and maximum two stable bumps) for small and moderate values of the relative inhibition time.

Structural integrity of power generating speed bumps made of concrete foam composite

NASA Astrophysics Data System (ADS)

Syam, B.; Muttaqin, M.; Hastrino, D.; Sebayang, A.; Basuki, W. S.; Sabri, M.; Abda, S.

2018-02-01

In this paper concrete foam composite speed bumps were designed to generate electrical power by utilizing the movements of commuting vehicles on highways, streets, parking gates, and drive-thru station of fast food restaurants. The speed bumps were subjected to loadings generated by vehicles pass over the power generating mechanical system. In this paper, we mainly focus our discussion on the structural integrity of the speed bumps and discuss the electrical power generating speed bumps in another paper. One aspect of structural integrity is its ability to support designed loads without breaking and includes the study of past structural failures in order to prevent failures in future designs. The concrete foam composites were used for the speed bumps; the reinforcement materials are selected from empty fruit bunch of oil palm. In this study, the speed bump materials and structure were subjected to various tests to obtain its physical and mechanical properties. To analyze the structure stability of the speed bumps some models were produced and tested in our speed bump test station. We also conduct a FEM-based computer simulation to analyze stress responses of the speed bump structures. It was found that speed bump type 1 significantly reduced the radial voltage. In addition, the speed bump is equipped with a steel casing is also suitable for use as a component component in generating electrical energy.

Transient thermal characteristics of high-temperature SiC power module enhanced with Al-bump technology

NASA Astrophysics Data System (ADS)

Tanisawa, Hidekazu; Kato, Fumiki; Koui, Kenichi; Sato, Shinji; Watanabe, Kinuyo; Takahashi, Hiroki; Murakami, Yoshinori; Sato, Hiroshi

2018-04-01

In this paper, we demonstrate a mounting technology that improves the tolerance to transient power loss by adding a heat capacity near the device. Silicon carbide (SiC) power devices can operate at high temperatures, up to 250 °C, at which silicon (Si) power devices cannot. Therefore, it is possible to allow a large temperature difference between the device and ambient air. Thus, the size of a power converter equipped with an SiC power module is reduced by simplifying the cooling system. The temperature of the power module is important not only in the steady state, but in transient loads as well. Therefore, we developed the Al-bump flip-chip mounting technology to increase heat capacity near the device. With this proposed structure, the heat capacity per device increased by 1.7% compared with the total heat capacity of the conventional structure using wire bonding. The reduction in transient thermal impedance is observed from 0.003 to 3 s, and we confirmed that the transient thermal impedance is reduced very efficiently by 15% at the maximum, compared with the conventional structure.

Effect of Joint Scale and Processing on the Fracture of Sn-3Ag-0.5Cu Solder Joints: Application to Micro-bumps in 3D Packages

NASA Astrophysics Data System (ADS)

Talebanpour, B.; Huang, Z.; Chen, Z.; Dutta, I.

2016-01-01

In 3-dimensional (3D) packages, a stack of dies is vertically connected to each other using through-silicon vias and very thin solder micro-bumps. The thinness of the micro-bumps results in joints with a very high volumetric proportion of intermetallic compounds (IMCs), rendering them much more brittle compared to conventional joints. Because of this, the reliability of micro-bumps, and the dependence thereof on the proportion of IMC in the joint, is of substantial concern. In this paper, the growth kinetics of IMCs in thin Sn-3Ag-0.5Cu joints attached to Cu substrates were analyzed, and empirical kinetic laws for the growth of Cu6Sn5 and Cu3Sn in thin joints were obtained. Modified compact mixed mode fracture mechanics samples, with adhesive solder joints between massive Cu substrates, having similar thickness and IMC content as actual micro-bumps, were produced. The effects of IMC proportion and strain rate on fracture toughness and mechanisms were investigated. It was found that the fracture toughness G C decreased with decreasing joint thickness ( h Joint). In addition, the fracture toughness decreased with increasing strain rate. Aging also promoted alternation of the crack path between the two joint-substrate interfaces, possibly proffering a mechanism to enhance fracture toughness.

Stochastic, adaptive sampling of information by microvilli in fly photoreceptors.

PubMed

Song, Zhuoyi; Postma, Marten; Billings, Stephen A; Coca, Daniel; Hardie, Roger C; Juusola, Mikko

2012-08-07

In fly photoreceptors, light is focused onto a photosensitive waveguide, the rhabdomere, consisting of tens of thousands of microvilli. Each microvillus is capable of generating elementary responses, quantum bumps, in response to single photons using a stochastically operating phototransduction cascade. Whereas much is known about the cascade reactions, less is known about how the concerted action of the microvilli population encodes light changes into neural information and how the ultrastructure and biochemical machinery of photoreceptors of flies and other insects evolved in relation to the information sampling and processing they perform. We generated biophysically realistic fly photoreceptor models, which accurately simulate the encoding of visual information. By comparing stochastic simulations with single cell recordings from Drosophila photoreceptors, we show how adaptive sampling by 30,000 microvilli captures the temporal structure of natural contrast changes. Following each bump, individual microvilli are rendered briefly (~100-200 ms) refractory, thereby reducing quantum efficiency with increasing intensity. The refractory period opposes saturation, dynamically and stochastically adjusting availability of microvilli (bump production rate: sample rate), whereas intracellular calcium and voltage adapt bump amplitude and waveform (sample size). These adapting sampling principles result in robust encoding of natural light changes, which both approximates perceptual contrast constancy and enhances novel events under different light conditions, and predict information processing across a range of species with different visual ecologies. These results clarify why fly photoreceptors are structured the way they are and function as they do, linking sensory information to sensory evolution and revealing benefits of stochasticity for neural information processing. Copyright © 2012 Elsevier Ltd. All rights reserved.

Stochastic, Adaptive Sampling of Information by Microvilli in Fly Photoreceptors

PubMed Central

Song, Zhuoyi; Postma, Marten; Billings, Stephen A.; Coca, Daniel; Hardie, Roger C.; Juusola, Mikko

2012-01-01

Summary Background In fly photoreceptors, light is focused onto a photosensitive waveguide, the rhabdomere, consisting of tens of thousands of microvilli. Each microvillus is capable of generating elementary responses, quantum bumps, in response to single photons using a stochastically operating phototransduction cascade. Whereas much is known about the cascade reactions, less is known about how the concerted action of the microvilli population encodes light changes into neural information and how the ultrastructure and biochemical machinery of photoreceptors of flies and other insects evolved in relation to the information sampling and processing they perform. Results We generated biophysically realistic fly photoreceptor models, which accurately simulate the encoding of visual information. By comparing stochastic simulations with single cell recordings from Drosophila photoreceptors, we show how adaptive sampling by 30,000 microvilli captures the temporal structure of natural contrast changes. Following each bump, individual microvilli are rendered briefly (∼100–200 ms) refractory, thereby reducing quantum efficiency with increasing intensity. The refractory period opposes saturation, dynamically and stochastically adjusting availability of microvilli (bump production rate: sample rate), whereas intracellular calcium and voltage adapt bump amplitude and waveform (sample size). These adapting sampling principles result in robust encoding of natural light changes, which both approximates perceptual contrast constancy and enhances novel events under different light conditions, and predict information processing across a range of species with different visual ecologies. Conclusions These results clarify why fly photoreceptors are structured the way they are and function as they do, linking sensory information to sensory evolution and revealing benefits of stochasticity for neural information processing. PMID:22704990

Self-assembly and reactive molding techniques for controlling the interface and dispersion of the particulate phase in nanocomposites

NASA Astrophysics Data System (ADS)

Pranger, Lawrence A.

This research explored the processing and properties of PNCs using a polyfurfural alcohol (PFA) matrix. The precursor for PFA, furfuryl alcohol (FA) is sourced from feedstocks rich in hemicellulose, such as corn cobs, oat hulls and wood. To exploit FA as a polymerizable solvent, cellulose whiskers (CW) and montmorillonite clay (MMT) were used as the nanoparticle phase. Results from PNC processing show that CW and MMT can be dispersed in the PFA matrix by means of insitu polymerization, without the use of surfactants or dilution in solvents. Both CW and MMT nanoparticles catalyze the polymerization of furfuryl alcohol (FA). Moreover, the insitu intercalative polymerization of FA in the interlayer galleries of MMT leads to the complete exfoliation of the MMT in the PFA matrix. CW and MMT both function as effective matrix modifiers, increasing the thermal stability of PFA nanocomposites compared to pure PFA polymer. The increased thermal stability is seen as significant increases in the onset of degradation and in residual weight at high temperature. This research also explored the surface functionalization of Cu, Ni and Pt substrates by self-assembly of a range of difunctional linker molecules. Characterization by XPS and PM-IRRAS indicate that diisocyanides and dicarboxylic acids both form chemically "sticky" surfaces after self-assembly on Cu and Ni. Sticky surfaces may provide a means of increasing nanoparticle dispersion in metal nanocluster filled PNCs, by increasing their interaction with the matrix polymer. Another potential application for sticky surfaces on Cu is in the ongoing miniaturization of circuit boards. The functionalization of Cu bond pad substrates with linker molecules may provide an alternate means of bonding components to their bond pads, with higher placement accuracy compared to solder bumps.

Computer analysis of flow perturbations generated by placement of choke bumps in a wind tunnel

NASA Technical Reports Server (NTRS)

Campbell, R. L.

1981-01-01

An inviscid analytical study was conducted to determine the upstream flow perturbations caused by placing choke bumps in a wind tunnel. A computer program based on the stream-tube curvature method was used to calculate the resulting flow fields for a nominal free-stream Mach number range of 0.6 to 0.9. The choke bump geometry was also varied to investigate the effect of bump shape on the disturbance produced. Results from the study indicate that a region of significant variation from the free-stream conditions exists upstream of the throat of the tunnel. The extent of the disturbance region was, as a rule, dependent on Mach number and the geometry of the choke bump. In general, the upstream disturbance distance decreased for increasing nominal free-stream Mach number and for decreasing length-to-height ratio of the bump. A polynomial-curve choke bump usually produced less of a disturbance than did a circular-arc bump and going to an axisymmetric configuration (modeling choke bumps on all the tunnel walls) generally resulted in a lower disturbance than with the corresponding two dimensional case.

Study of Electromigration-Induced Failures on Cu Pillar Bumps Joined to OSP and ENEPIG Substrates

NASA Astrophysics Data System (ADS)

Hsiao, Yu-Hsiang; Lin, Kwang-Lung; Lee, Chiu-Wen; Shao, Yu-Hsiu; Lai, Yi-Shao

2012-12-01

This work studies electromigration (EM)-induced failures on Cu pillar bumps joined to organic solderability preservative (OSP) on Cu substrates (OSP-bumps) and electroless Ni(P)/electroless Pd/immersion Au (ENEPIG) under bump metallurgy (UBM) on Cu substrates (ENEPIG-bumps). Two failure modes (Cu pad consumption and gap formation) were found with OSP-bumps, but only one failure mode (gap formation) was found with ENEPIG-bumps. The main interfacial compound layer was the Cu6Sn5 compound, which suffered significant EM-induced dissolution, eventually resulting in severe Cu pad consumption at the cathode side for OSP-bumps. A (Cu,Ni)6Sn5 layer with strong resistance to EM-induced dissolution exists at the joint interface when a nickel barrier layer is incorporated at the cathode side (Ni or ENEPIG), and these imbalanced atomic fluxes result in the voids and gap formation. OSP-bumps showed better lifetime results than ENEPIG-bumps for several current stressing conditions. The inverse Cu atomic flux ( J Cu,chem) which diffuses from the Cu pad to cathode side retards the formation of voids. The driving force for J Cu,chem comes from the difference in chemical potential between the (Cu,Ni)6Sn5 and Cu6Sn5 phases.

A novel method for direct solder bump pull testing using lead-free solders

NASA Astrophysics Data System (ADS)

Turner, Gregory Alan

This thesis focuses on the design, fabrication, and evaluation of a new method for testing the adhesion strength of lead-free solders, named the Isotraction Bump Pull method (IBP). In order to develop a direct solder joint-strength testing method that did not require customization for different solder types, bump sizes, specific equipment, or trial-and-error, a combination of two widely used and accepted standards was created. First, solder bumps were made from three types of lead free solder were generated on untreated copper PCB substrates using an in-house fabricated solder bump-on-demand generator, Following this, the newly developed method made use of a polymer epoxy to encapsulate the solder bumps that could then be tested under tension using a high precision universal vertical load machine. The tests produced repeatable and predictable results for each of the three alloys tested that were in agreement with the relative behavior of the same alloys using other testing methods in the literature. The median peak stress at failure for the three solders tested were 2020.52 psi, 940.57 psi, and 2781.0 psi, and were within one standard deviation of the of all data collected for each solder. The assumptions in this work that brittle fracture occurred through the Intermetallic Compound layer (IMC) were validated with the use of Energy-Dispersive X-Ray Spectrometry and high magnification of the fractured surface of both newly exposed sides of the test specimens. Following this, an examination of the process to apply the results from the tensile tests into standard material science equations for the fracture of the systems was performed..

Recent Advances in Understanding the Reminiscence Bump: The Importance of Cues in Guiding Recall from Autobiographical Memory

PubMed Central

Koppel, Jonathan; Rubin, David C.

2016-01-01

The reminiscence bump is the increased proportion of autobiographical memories from youth and early adulthood observed in adults over 40. It is one of the most robust findings in autobiographical memory research. Although described as a single period of increased memories, a recent meta-analysis which reported the beginning and ending ages of the bump from individual studies found that different classes of cues produce distinct bumps that vary in size and temporal location. The bump obtained in response to cue words is both smaller and located earlier in the lifespan than the bump obtained when important memories are requested. The bump obtained in response to odor cues is even earlier. This variation in the size and location of the reminiscence bump argues for theories based primarily on retrieval rather than encoding and retention, which most current theories stress. Furthermore, it points to the need to develop theories of autobiographical memory that account for this flexibility in the memories retrieved. PMID:27141156

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

Khalid, Farah F.; Deptuch, Grzegorz; Shenai, Alpana

Monolithic Active Matrix with Binary Counters (MAMBO) is a counting ASIC designed for detecting and measuring low energy X-rays from 6-12 keV. Each pixel contains analogue functionality implemented with a charge preamplifier, CR-RC{sup 2} shaper and a baseline restorer. It also contains a window comparator which can be trimmed by 4 bit DACs to remove systematic offsets. The hits are registered by a 12 bit ripple counter which is reconfigured as a shift register to serially output the data from the entire ASIC. Each pixel can be tested individually. Two diverse approaches have been used to prevent coupling between themore » detector and electronics in MAMBO III and MAMBO IV. MAMBO III is a 3D ASIC, the bottom ASIC consists of diodes which are connected to the top ASIC using {mu}-bump bonds. The detector is decoupled from the electronics by physically separating them on two tiers and using several metal layers as a shield. MAMBO IV is a monolithic structure which uses a nested well approach to isolate the detector from the electronics. The ASICs are being fabricated using the SOI 0.2 {micro}m OKI process, MAMBO III is 3D bonded at T-Micro and MAMBO IV nested well structure was developed in collaboration between OKI and Fermilab.« less

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

Khalid, Farah; Deptuch, Grzegorz; Shenai, Alpana

Monolithic Active Matrix with Binary Counters (MAMBO) is a counting ASIC designed for detecting and measuring low energy X-rays from 6-12keV. Each pixel contains analogue functionality implemented with a charge preamplifier, CR-RC{sup 2} shaper and a baseline restorer. It also contains a window comparator which can be trimmed by 4 bit DACs to remove systematic offsets. The hits are registered by a 12 bit ripple counter which is reconfigured as a shift register to serially output the data from the entire ASIC. Each pixel can be tested individually. Two diverse approaches have been used to prevent coupling between the detectormore » and electronics in MAMBO III and MAMBO IV. MAMBO III is a 3D ASIC, the bottom ASIC consists of diodes which are connected to the top ASIC using {mu}-bump bonds. The detector is decoupled from the electronics by physically separating them on two tiers and using several metal layers as a shield. MAMBO IV is a monolithic structure which uses a nested well approach to isolate the detector from the electronics. The ASICs are being fabricated using the SOI 0.2 {micro}m OKI process, MAMBO III is 3D bonded at T-Micro and MAMBO IV nested well structure was developed in collaboration between OKI and Fermilab.« less

Non-independent quantum bumps in Limulus ventral nerve photoreceptors--a new insight in the light transduction mechanism.

PubMed

Nagy, K

1992-09-14

Single photon-induced transient currents, called quantum bumps were stimulated by short flashes in dark-adapted ventral nerve photoreceptors of Limulus. Flash intensities were set to activate 3 or more bumps. In most cases, current bumps were activated with a constant rate. The frequency of bump occurrence was between 9 and 17 Hz. Results show that consecutive bumps are not independent and that some of them are not activated by a photon. The periodic bump activation indicates a molecular mechanism which quantifies the transmitter release not only by a light quantum, but also by a late phase of the transduction cascade. A model is proposed, in which Ca2+ ions released from intracellular stores transiently block the further Ca2+ release by inositol trisphosphate in an all-or-none manner.

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

Bauer, R.; Ebersberger, B.; Kupfer, C.

SnAg solder bump is one bump type which is used to replace eutectic SnPb bumps. In this work tests have been done to characterize the reliability properties of this bump type. Electromigration (EM) tests, which were accelerated by high current and high temperature and high temperature storage (HTS) tests were performed. It was found that the reliability properties are sensitive to the material combinations in the interconnect stack. The interconnect stack includes substrate pad, pad finish, bump, underbump metallization (UBM) and the chip pad. Therefore separate test groups for SnAg bumps on Cu substrate pads with organic solderability preservative (OSP)more » finish and the identical bumps on pads with Ni/Au finish were used. In this paper the reliability test results and the corresponding failure analysis are presented. Some explanations about the differences in formation of intermetallic compounds (IMCs) are given.« less

By the People, for the People: the Crowdsourcing of "STREETBUMP": AN Automatic Pothole Mapping App

NASA Astrophysics Data System (ADS)

Carrera, F.; Guerin, S.; Thorp, J. B.

2013-05-01

This paper traces the genesis and development of StreetBump, a smartphone application to map the location of potholes in Boston, Massachusetts. StreetBump belongs to a special category of "subliminal" crowdsourcing mobile applications that turn humans into sensors. Once started, it automatically collects road condition information without any human intervention, using the accelerometers and GPS inside smartphones. The StreetBump app evolved from a hardware device designed and built by WPI's City Lab starting in 2003, which was originally intended to measure and map boat wakes in the city of Venice, Italy (Chiu, 2004). A second version of the custom hardware with onboard GPS and accelerometers was adapted to use in Boston, Massachusetts, to map road damage (potholes) in 2006 (Angelini, 2006). In 2009, Prof. Carrera proposed to the newly created office of New Urban Mechanics in the City of Boston to migrate the concept to Smartphones, based on the Android platform. The first prototype of the mobile app, called StreetBump, was released in 2010 by the authors (Harmon, 2010). In 2011, the app provided the basis for a worldwide Innocentive competition to develop the best postprocessing algorithms to identify the real potholes vs. other phone bumps (Moskowitz, 2011). Starting in 2012, the City of Boston has begun using a subsequent version of the app to operationally manage road repairs based on the data collected by StreetBump. The novelty of this app is not purely technological, but lies also in the top-to-bottom crowdsourcing of all its components. The app was designed to rely on the crowd to confirm the presence of damage though repeat hits (or lack thereof) as more users travel the same roads over time. Moreover, the non-trivial post-processing of the StreetBump data was itself the subject of a crowdsourced competition through an Innocentive challenge for the best algorithm. The release of the StreetBump code as open-source allowed the development of the final version of the app now used on a daily basis by the Department of Public Works in Boston, thus making it perhaps the first example of an app that was crowdsourced "from soup to nuts".

3-Axis Fully-Integrated Capacitive Tactile Sensor with Flip-Bonded CMOS on LTCC Interposer.

PubMed

Asano, Sho; Muroyama, Masanori; Nakayama, Takahiro; Hata, Yoshiyuki; Nonomura, Yutaka; Tanaka, Shuji

2017-10-25

This paper reports a 3-axis fully integrated differential capacitive tactile sensor surface-mountable on a bus line. The sensor integrates a flip-bonded complementary metal-oxide semiconductor (CMOS) with capacitive sensing circuits on a low temperature cofired ceramic (LTCC) interposer with Au through vias by Au-Au thermo-compression bonding. The CMOS circuit and bonding pads on the sensor backside were electrically connected through Au bumps and the LTCC interposer, and the differential capacitive gap was formed by an Au sealing frame. A diaphragm for sensing 3-axis force was formed in the CMOS substrate. The dimensions of the completed sensor are 2.5 mm in width, 2.5 mm in length, and 0.66 mm in thickness. The fabricated sensor output coded 3-axis capacitive sensing data according to applied 3-axis force by three-dimensional (3D)-printed pins. The measured sensitivity was as high as over 34 Count/mN for normal force and 14 to 15 Count/mN for shear force with small noise, which corresponds to less than 1 mN. The hysteresis and the average cross-sensitivity were also found to be less than 2% full scale and 11%, respectively.

3-Axis Fully-Integrated Capacitive Tactile Sensor with Flip-Bonded CMOS on LTCC Interposer †

PubMed Central

Asano, Sho; Nakayama, Takahiro; Hata, Yoshiyuki; Tanaka, Shuji

2017-01-01

This paper reports a 3-axis fully integrated differential capacitive tactile sensor surface-mountable on a bus line. The sensor integrates a flip-bonded complementary metal-oxide semiconductor (CMOS) with capacitive sensing circuits on a low temperature cofired ceramic (LTCC) interposer with Au through vias by Au-Au thermo-compression bonding. The CMOS circuit and bonding pads on the sensor backside were electrically connected through Au bumps and the LTCC interposer, and the differential capacitive gap was formed by an Au sealing frame. A diaphragm for sensing 3-axis force was formed in the CMOS substrate. The dimensions of the completed sensor are 2.5 mm in width, 2.5 mm in length, and 0.66 mm in thickness. The fabricated sensor output coded 3-axis capacitive sensing data according to applied 3-axis force by three-dimensional (3D)-printed pins. The measured sensitivity was as high as over 34 Count/mN for normal force and 14 to 15 Count/mN for shear force with small noise, which corresponds to less than 1 mN. The hysteresis and the average cross-sensitivity were also found to be less than 2% full scale and 11%, respectively. PMID:29068429

Application of the adjoint optimisation of shock control bump for ONERA-M6 wing

NASA Astrophysics Data System (ADS)

Nejati, A.; Mazaheri, K.

2017-11-01

This article is devoted to the numerical investigation of the shock wave/boundary layer interaction (SWBLI) as the main factor influencing the aerodynamic performance of transonic bumped airfoils and wings. The numerical analysis is conducted for the ONERA-M6 wing through a shock control bump (SCB) shape optimisation process using the adjoint optimisation method. SWBLI is analyzed for both clean and bumped airfoils and wings, and it is shown how the modified wave structure originating from upstream of the SCB reduces the wave drag, by improving the boundary layer velocity profile downstream of the shock wave. The numerical simulation of the turbulent viscous flow and a gradient-based adjoint algorithm are used to find the optimum location and shape of the SCB for the ONERA-M6 airfoil and wing. Two different geometrical models are introduced for the 3D SCB, one with linear variations, and another with periodic variations. Both configurations result in drag reduction and improvement in the aerodynamic efficiency, but the periodic model is more effective. Although the three-dimensional flow structure involves much more complexities, the overall results are shown to be similar to the two-dimensional case.

Temporal distribution of favourite books, movies, and records: differential encoding and re-sampling.

PubMed

Janssen, Steve M J; Chessa, Antonio G; Murre, Jaap M J

2007-10-01

The reminiscence bump is the effect that people recall more personal events from early adulthood than from childhood or adulthood. The bump has been examined extensively. However, the question of whether the bump is caused by differential encoding or re-sampling is still unanswered. To examine this issue, participants were asked to name their three favourite books, movies, and records. Furthermore,they were asked when they first encountered them. We compared the temporal distributions and found that they all showed recency effects and reminiscence bumps. The distribution of favourite books had the largest recency effect and the distribution of favourite records had the largest reminiscence bump. We can explain these results by the difference in rehearsal. Books are read two or three times, movies are watched more frequently, whereas records are listened to numerous times. The results suggest that differential encoding initially causes the reminiscence bump and that re-sampling increases the bump further.

New Patterns of Activity in a Pair of Interacting Excitatory-Inhibitory Neural Fields

NASA Astrophysics Data System (ADS)

Folias, S. E.; Ermentrout, G. B.

2011-11-01

In this Letter, we study stationary bump solutions in a pair of interacting excitatory-inhibitory (E-I) neural fields in one dimension. We demonstrate the existence of localized bump solutions of persistent activity that can be maintained by the pair of interacting layers when a stationary bump is not supported by either layer in isolation—a scenario which may be relevant as a mechanism for the persistent activity associated with working memory in the prefrontal cortex and may explain why bumps are not seen in in vitro slice preparations. Furthermore, we describe a new type of stationary bump solution arising from a pitchfork bifurcation which produces a stationary bump in each layer with a spatial offset that increases with the bifurcation parameter.

On the persistence of unstable bump-on-tail electron velocity distributions in the earth's foreshock

NASA Technical Reports Server (NTRS)

Klimas, Alexander J.; Fitzenreiter, Richard J.

1988-01-01

This paper presents further evidence for the persistence of bump-on-tail unstable reduced velocity distributions in the earth's electron foreshock, which contradicts the understanding of quasi-linear saturation of the bump-on-tail instability. A modified theory for the saturation of the bump-on-tail instability in the earth's foreshock is proposed to explain the mechanism of this persistence, and the predictions are compared to the results of a numerical simulation of the electron plasma in the foreshock. The results support the thesis that quasi-linear saturation of the bump-on-tail instability is modified in the foreshock, due to the driven nature of the region, so that at saturation the stabilized velocity distribution still appears bump-on-tail unstable to linear plasma analysis.

Silicon pixel-detector R&D for CLIC

NASA Astrophysics Data System (ADS)

Nürnberg, A.

2016-11-01

The physics aims at the future CLIC high-energy linear e+e- collider set very high precision requirements on the performance of the vertex and tracking detectors. Moreover, these detectors have to be well adapted to the experimental conditions, such as the time structure of the collisions and the presence of beam-induced backgrounds. The principal challenges are: a point resolution of a few μm, ultra-low mass (~ 0.2%X0 per layer for the vertex region and ~ 1%X0 per layer for the outer tracker), very low power dissipation (compatible with air-flow cooling in the inner vertex region) and pulsed power operation, complemented with ~ 10 ns time stamping capabilities. A highly granular all-silicon vertex and tracking detector system is under development, following an integrated approach addressing simultaneously the physics requirements and engineering constraints. For the vertex-detector region, hybrid pixel detectors with small pitch (25 μm) and analog readout are explored. For the outer tracking region, both hybrid concepts and fully integrated CMOS sensors are under consideration. The feasibility of ultra-thin sensor layers is validated with Timepix3 readout ASICs bump bonded to active edge planar sensors with 50 μm to 150 μm thickness. Prototypes of CLICpix readout ASICs implemented in 6525 nm CMOS technology with 25 μm pixel pitch have been produced. Hybridisation concepts have been developed for interconnecting these chips either through capacitive coupling to active HV-CMOS sensors or through bump-bonding to planar sensors. Recent R&D achievements include results from beam tests with all types of hybrid assemblies. Simulations based on Geant4 and TCAD are used to validate the experimental results and to assess and optimise the performance of various detector designs.

ASIC Readout Circuit Architecture for Large Geiger Photodiode Arrays

NASA Technical Reports Server (NTRS)

Vasile, Stefan; Lipson, Jerold

2012-01-01

The objective of this work was to develop a new class of readout integrated circuit (ROIC) arrays to be operated with Geiger avalanche photodiode (GPD) arrays, by integrating multiple functions at the pixel level (smart-pixel or active pixel technology) in 250-nm CMOS (complementary metal oxide semiconductor) processes. In order to pack a maximum of functions within a minimum pixel size, the ROIC array is a full, custom application-specific integrated circuit (ASIC) design using a mixed-signal CMOS process with compact primitive layout cells. The ROIC array was processed to allow assembly in bump-bonding technology with photon-counting infrared detector arrays into 3-D imaging cameras (LADAR). The ROIC architecture was designed to work with either common- anode Si GPD arrays or common-cathode InGaAs GPD arrays. The current ROIC pixel design is hardwired prior to processing one of the two GPD array configurations, and it has the provision to allow soft reconfiguration to either array (to be implemented into the next ROIC array generation). The ROIC pixel architecture implements the Geiger avalanche quenching, bias, reset, and time to digital conversion (TDC) functions in full-digital design, and uses time domain over-sampling (vernier) to allow high temporal resolution at low clock rates, increased data yield, and improved utilization of the laser beam.

Salvaged castings and methods of salvaging castings with defective cast cooling bumps

DOEpatents

Johnson, Robert Alan; Schaeffer, Jon Conrad; Lee, Ching-Pang; Abuaf, Nesim; Hasz, Wayne Charles

2002-01-01

Castings for gas turbine parts exposed on one side to a high-temperature fluid medium have cast-in bumps on an opposite cooling surface side to enhance heat transfer. Areas on the cooling surface having defectively cast bumps, i.e., missing or partially formed bumps during casting, are coated with a braze alloy and cooling enhancement material to salvage the part.

Chalcogenide phase-change thin films used as grayscale photolithography materials.

PubMed

Wang, Rui; Wei, Jingsong; Fan, Yongtao

2014-03-10

Chalcogenide phase-change thin films are used in many fields, such as optical information storage and solid-state memory. In this work, we present another application of chalcogenide phase-change thin films, i.e., as grayscale photolithgraphy materials. The grayscale patterns can be directly inscribed on the chalcogenide phase-change thin films by a single process through direct laser writing method. In grayscale photolithography, the laser pulse can induce the formation of bump structure, and the bump height and size can be precisely controlled by changing laser energy. Bumps with different height and size present different optical reflection and transmission spectra, leading to the different gray levels. For example, the continuous-tone grayscale images of lifelike bird and cat are successfully inscribed onto Sb(2)Te(3) chalcogenide phase-change thin films using a home-built laser direct writer, where the expression and appearance of the lifelike bird and cat are fully presented. This work provides a way to fabricate complicated grayscale patterns using laser-induced bump structures onto chalcogenide phase-change thin films, different from current techniques such as photolithography, electron beam lithography, and focused ion beam lithography. The ability to form grayscale patterns of chalcogenide phase-change thin films reveals many potential applications in high-resolution optical images for micro/nano image storage, microartworks, and grayscale photomasks.

Electromigration kinetics and critical current of Pb-free interconnects

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

Lu, Minhua; Rosenberg, Robert

2014-04-07

Electromigration kinetics of Pb-free solder bump interconnects have been studied using a single bump parameter sweep technique. By removing bump to bump variations in structure, texture, and composition, the single bump sweep technique has provided both activation energy and power exponents that reflect atomic migration and interface reactions with fewer samples, shorter stress time, and better statistics than standard failure testing procedures. Contact metallurgies based on Cu and Ni have been studied. Critical current, which corresponds to the Blech limit, was found to exist in the Ni metallurgy, but not in the Cu metallurgy. A temperature dependence of critical currentmore » was also observed.« less

Enhanced heat transfer surface for cast-in-bump-covered cooling surfaces and methods of enhancing heat transfer

DOEpatents

Chiu, Rong-Shi Paul; Hasz, Wayne Charles; Johnson, Robert Alan; Lee, Ching-Pang; Abuaf, Nesim

2002-01-01

An annular turbine shroud separates a hot gas path from a cooling plenum containing a cooling medium. Bumps are cast in the surface on the cooling side of the shroud. A surface coating overlies the cooling side surface of the shroud, including the bumps, and contains cooling enhancement material. The surface area ratio of the cooling side of the shroud with the bumps and coating is in excess of a surface area ratio of the cooling side surface with bumps without the coating to afford increased heat transfer across the element relative to the heat transfer across the element without the coating.

Cell responses to single pheromone molecules may reflect the activation kinetics of olfactory receptor molecules.

PubMed

Minor, A V; Kaissling, K-E

2003-03-01

Olfactory receptor cells of the silkmoth Bombyx mori respond to single pheromone molecules with "elementary" electrical events that appear as discrete "bumps" a few milliseconds in duration, or bursts of bumps. As revealed by simulation, one bump may result from a series of random openings of one or several ion channels, producing an average inward membrane current of 1.5 pA. The distributions of durations of bumps and of gaps between bumps in a burst can be fitted by single exponentials with time constants of 10.2 ms and 40.5 ms, respectively. The distribution of burst durations is a sum of two exponentials; the number of bumps per burst obeyed a geometric distribution (mean 3.2 bumps per burst). Accordingly the elementary events could reflect transitions among three states of the pheromone receptor molecule: the vacant receptor (state 1), the pheromone-receptor complex (state 2), and the activated complex (state 3). The calculated rate constants of the transitions between states are k(21)=7.7 s(-1), k(23)=16.8 s(-1), and k(32)=98 s(-1).

Beam test results of the BTeV silicon pixel detector

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

Gabriele Chiodini et al.

2000-09-28

The authors have described the results of the BTeV silicon pixel detector beam test. The pixel detectors under test used samples of the first two generations of Fermilab pixel readout chips, FPIX0 and FPIX1, (indium bump-bonded to ATLAS sensor prototypes). The spatial resolution achieved using analog charge information is excellent for a large range of track inclination. The resolution is still very good using only 2-bit charge information. A relatively small dependence of the resolution on bias voltage is observed. The resolution is observed to depend dramatically on the discriminator threshold, and it deteriorates rapidly for threshold above 4000e{sup {minus}}.

Hybrid UV Imager Containing Face-Up AlGaN/GaN Photodiodes

NASA Technical Reports Server (NTRS)

Zheng, Xinyu; Pain, Bedabrata

2005-01-01

A proposed hybrid ultraviolet (UV) image sensor would comprise a planar membrane array of face-up AlGaN/GaN photodiodes integrated with a complementary metal oxide/semiconductor (CMOS) readout-circuit chip. Each pixel in the hybrid image sensor would contain a UV photodiode on the AlGaN/GaN membrane, metal oxide/semiconductor field-effect transistor (MOSFET) readout circuitry on the CMOS chip underneath the photodiode, and a metal via connection between the photodiode and the readout circuitry (see figure). The proposed sensor design would offer all the advantages of comparable prior CMOS active-pixel sensors and AlGaN UV detectors while overcoming some of the limitations of prior (AlGaN/sapphire)/CMOS hybrid image sensors that have been designed and fabricated according to the methodology of flip-chip integration. AlGaN is a nearly ideal UV-detector material because its bandgap is wide and adjustable and it offers the potential to attain extremely low dark current. Integration of AlGaN with CMOS is necessary because at present there are no practical means of realizing readout circuitry in the AlGaN/GaN material system, whereas the means of realizing readout circuitry in CMOS are well established. In one variant of the flip-chip approach to integration, an AlGaN chip on a sapphire substrate is inverted (flipped) and then bump-bonded to a CMOS readout circuit chip; this variant results in poor quantum efficiency. In another variant of the flip-chip approach, an AlGaN chip on a crystalline AlN substrate would be bonded to a CMOS readout circuit chip; this variant is expected to result in narrow spectral response, which would be undesirable in many applications. Two other major disadvantages of flip-chip integration are large pixel size (a consequence of the need to devote sufficient area to each bump bond) and severe restriction on the photodetector structure. The membrane array of AlGaN/GaN photodiodes and the CMOS readout circuit for the proposed image sensor would be fabricated separately.

Phospholipase C mediated Suppression of Dark Noise Enables Single Photon Detection in Drosophila Photoreceptors

PubMed Central

Katz, Ben; Minke, Baruch

2012-01-01

Drosophila photoreceptor cells use the ubiquitous G-protein-mediated phospholipase C (PLC) cascade to achieve ultimate single photon sensitivity. This is manifested in the single photon responses (quantum bumps). In photoreceptor cells, dark activation of Gqα molecules occurs spontaneously and produces unitary dark events (dark bumps). A high rate of spontaneous Gqα activation and dark bump production potentially hampers single photon detection. We found that in wild type flies the in vivo rate of spontaneous Gqα activation is very high. Nevertheless, this high rate is not manifested in a substantially high rate of dark bumps. Therefore, it is unclear how phototransduction suppresses dark bump production, arising from spontaneous Gqα activation, while still maintaining high-fidelity representation of single photons. In this study we show that reduced PLC catalytic activity selectively suppressed production of dark bumps but not light-induced bumps. Manipulations of PLC activity using PLC mutant flies and Ca2+ modulations revealed that a critical level of PLC activity is required to induce bump production. The required minimal level of PLC activity, selectively suppressed random production of single Gqα-activated dark bumps despite a high rate of spontaneous Gqα activation. This minimal PLC activity level is reliably obtained by photon induced synchronized activation of several neighboring Gqα molecules activating several PLC molecules, but not by random activation of single Gqα molecules. We thus demonstrate how a G-protein-mediated transduction system, with PLC as its target, selectively suppresses its intrinsic noise while preserving reliable signaling. PMID:22357856

Tribology: Diamonds are forever - or are they?

NASA Astrophysics Data System (ADS)

Fineberg, Jay

2011-01-01

The friction and wear of materials is part of our everyday experience, and yet these processes are not well understood. The example of diamond highlights wear processes that result from bumping atoms, showing that the devil is indeed in the details.

Transforming in-situ observations of CME-driven shock accelerated protons into the shock's reference frame.

NASA Astrophysics Data System (ADS)

Robinson, I. M.; Simnett, G. M.

2005-07-01

We examine the solar energetic particle event following solar activity from 14, 15 April 2001 which includes a "bump-on-the-tail" in the proton energy spectra at 0.99 AU from the Sun. We find this population was generated by a CME-driven shock which arrived at 0.99 AU around midnight 18 April. As such this population represents an excellent opportunity to study in isolation, the effects of proton acceleration by the shock. The peak energy of the bump-on-the-tail evolves to progressively lower energies as the shock approaches the observing spacecraft at the inner Lagrange point. Focusing on the evolution of this peak energy we demonstrate a technique which transforms these in-situ spectral observations into a frame of reference co-moving with the shock whilst making allowance for the effects of pitch angle scattering and focusing. The results of this transform suggest the bump-on-the-tail population was not driven by the 15 April activity but was generated or at least modulated by a CME-driven shock which left the Sun on 14 April. The existence of a bump-on-the-tail population is predicted by models in Rice et al. (2003) and Li et al. (2003) which we compare with observations and the results of our analysis in the context of both the 14 April and 15 April CMEs. We find an origin of the bump-on-the-tail at the 14 April CME-driven shock provides better agreement with these modelled predictions although some discrepancy exists as to the shock's ability to accelerate 100 MeV protons. Keywords. Solar physics, astrophysics and astronomy (Energetic particles; Flares and mass ejections) Space plasma physics (Transport processes)

Sequential shrink photolithography for plastic microlens arrays

NASA Astrophysics Data System (ADS)

Dyer, David; Shreim, Samir; Jayadev, Shreshta; Lew, Valerie; Botvinick, Elliot; Khine, Michelle

2011-07-01

Endeavoring to push the boundaries of microfabrication with shrinkable polymers, we have developed a sequential shrink photolithography process. We demonstrate the utility of this approach by rapidly fabricating plastic microlens arrays. First, we create a mask out of the children's toy Shrinky Dinks by simply printing dots using a standard desktop printer. Upon retraction of this pre-stressed thermoplastic sheet, the dots shrink to a fraction of their original size, which we then lithographically transfer onto photoresist-coated commodity shrink wrap film. This shrink film reduces in area by 95% when briefly heated, creating smooth convex photoresist bumps down to 30 µm. Taken together, this sequential shrink process provides a complete process to create microlenses, with an almost 99% reduction in area from the original pattern size. Finally, with a lithography molding step, we emboss these bumps into optical grade plastics such as cyclic olefin copolymer for functional microlens arrays.

Sequential shrink photolithography for plastic microlens arrays.

PubMed

Dyer, David; Shreim, Samir; Jayadev, Shreshta; Lew, Valerie; Botvinick, Elliot; Khine, Michelle

2011-07-18

Endeavoring to push the boundaries of microfabrication with shrinkable polymers, we have developed a sequential shrink photolithography process. We demonstrate the utility of this approach by rapidly fabricating plastic microlens arrays. First, we create a mask out of the children's toy Shrinky Dinks by simply printing dots using a standard desktop printer. Upon retraction of this pre-stressed thermoplastic sheet, the dots shrink to a fraction of their original size, which we then lithographically transfer onto photoresist-coated commodity shrink wrap film. This shrink film reduces in area by 95% when briefly heated, creating smooth convex photoresist bumps down to 30 µm. Taken together, this sequential shrink process provides a complete process to create microlenses, with an almost 99% reduction in area from the original pattern size. Finally, with a lithography molding step, we emboss these bumps into optical grade plastics such as cyclic olefin copolymer for functional microlens arrays.

Sequential shrink photolithography for plastic microlens arrays

PubMed Central

Dyer, David; Shreim, Samir; Jayadev, Shreshta; Lew, Valerie; Botvinick, Elliot; Khine, Michelle

2011-01-01

Endeavoring to push the boundaries of microfabrication with shrinkable polymers, we have developed a sequential shrink photolithography process. We demonstrate the utility of this approach by rapidly fabricating plastic microlens arrays. First, we create a mask out of the children’s toy Shrinky Dinks by simply printing dots using a standard desktop printer. Upon retraction of this pre-stressed thermoplastic sheet, the dots shrink to a fraction of their original size, which we then lithographically transfer onto photoresist-coated commodity shrink wrap film. This shrink film reduces in area by 95% when briefly heated, creating smooth convex photoresist bumps down to 30 µm. Taken together, this sequential shrink process provides a complete process to create microlenses, with an almost 99% reduction in area from the original pattern size. Finally, with a lithography molding step, we emboss these bumps into optical grade plastics such as cyclic olefin copolymer for functional microlens arrays. PMID:21863126

Effect of wettability and topological features of Namib beetle inspired bumps on dropwise condensation

NASA Astrophysics Data System (ADS)

Ahmad, Shakeel; Tang, Hui; Yao, Haimin

2017-11-01

The Stenocara beetle lives in arid desert environment where the only available source of water is fog droplets. The beetle contains many hydrophobic/hydrophilic bumps on its back. Water collection occurs on the hydrophilic patches. Once the droplet reaches the critical volume, it sheds down due to gravity. Although a number of studies on condensation and water collection on beetle inspired structures have been reported in literature, most of them were on micro/nano scale textures. However, in nature the beetle bumps are in millimeter scale. At this scale the role of topological features and gravity becomes crucial for early droplet shedding. Therefore, in this work we numerically investigated the effects of bump shape, wettability contrast, surface slope and hydrophilic patch to total area ratio on droplet shedding volume and time. A three-dimensional lattice Boltzmann method (LBM) based numerical framework was used for the simulations. Compared with bumps of other shapes such a cube or a circular cylinder, faster droplet shedding was obtained over a hemispherical bump. Furthermore, it was found that larger hydrophilic patch to total area ratio for the hemispherical bump significantly increased the droplet shedding time.

The Effects of Extravehicular Activity (EVA) Glove Pressure on Tactility

NASA Technical Reports Server (NTRS)

Thompson, Shelby; Miranda, Mesloh; England, Scott; Benson, Elizabeth; Rajulu, Sudhakar

2010-01-01

The purpose of the current study was to quantify finger tactility, while wearing a Phase VI Extravehicular Activity (EVA) glove. Subjects were fully suited in an Extravehicular Mobility Unit (EMU) suit. Data was collected under three conditions: bare-handed, gloved at 0 psi, and gloved at 4.3 psi. In order to test tactility, a series of 30 tactile stimuli (bumps) were created that varied in both height and width. With the hand obscured, subjects applied pressure to each bump until detected tactilely. The amount of force needed to detect each bump was recorded using load cells located under a force-plate. The amount of force needed to detect a bump was positively related to width, but inversely related to height. In addition, as the psi of the glove increased, more force was needed to detect the bump. In terms of application, it was possible to determine the optimal width and height a bump needs to be for a specific amount of force applied for tactility.

On the Application of Contour Bumps for Transonic Drag Reduction(Invited)

NASA Technical Reports Server (NTRS)

Milholen, William E., II; Owens, Lewis R.

2005-01-01

The effect of discrete contour bumps on reducing the transonic drag at off-design conditions on an airfoil have been examined. The research focused on fully-turbulent flow conditions, at a realistic flight chord Reynolds number of 30 million. State-of-the-art computational fluid dynamics methods were used to design a new baseline airfoil, and a family of fixed contour bumps. The new configurations were experimentally evaluated in the 0.3-m Transonic Cryogenic Tunnel at the NASA Langley Research center, which utilizes an adaptive wall test section to minimize wall interference. The computational study showed that transonic drag reduction, on the order of 12% - 15%, was possible using a surface contour bump to spread a normal shock wave. The computational study also indicated that the divergence drag Mach number was increased for the contour bump applications. Preliminary analysis of the experimental data showed a similar contour bump effect, but this data needed to be further analyzed for residual wall interference corrections.

Body-terrain interaction affects large bump traversal of insects and legged robots.

PubMed

Gart, Sean W; Li, Chen

2018-02-02

Small animals and robots must often rapidly traverse large bump-like obstacles when moving through complex 3D terrains, during which, in addition to leg-ground contact, their body inevitably comes into physical contact with the obstacles. However, we know little about the performance limits of large bump traversal and how body-terrain interaction affects traversal. To address these, we challenged the discoid cockroach and an open-loop six-legged robot to dynamically run into a large bump of varying height to discover the maximal traversal performance, and studied how locomotor modes and traversal performance are affected by body-terrain interaction. Remarkably, during rapid running, both the animal and the robot were capable of dynamically traversing a bump much higher than its hip height (up to 4 times the hip height for the animal and 3 times for the robot, respectively) at traversal speeds typical of running, with decreasing traversal probability with increasing bump height. A stability analysis using a novel locomotion energy landscape model explained why traversal was more likely when the animal or robot approached the bump with a low initial body yaw and a high initial body pitch, and why deflection was more likely otherwise. Inspired by these principles, we demonstrated a novel control strategy of active body pitching that increased the robot's maximal traversable bump height by 75%. Our study is a major step in establishing the framework of locomotion energy landscapes to understand locomotion in complex 3D terrains.

How bumps on whale flippers delay stall: an aerodynamic model.

PubMed

van Nierop, Ernst A; Alben, Silas; Brenner, Michael P

2008-02-08

Wind tunnel experiments have shown that bumps on the leading edge of model humpback whale flippers cause them to "stall" (i.e., lose lift dramatically) more gradually and at a higher angle of attack. Here we develop an aerodynamic model which explains the observed increase in stall angle. The model predicts that as the amplitude of the bumps is increased, the lift curve flattens out, leading to potentially desirable control properties. We find that stall delay is insensitive to the wavelength of the bumps, in accordance with experimental observations.

Thermal cycling reliability of Cu/SnAg double-bump flip chip assemblies for 100 μm pitch applications

NASA Astrophysics Data System (ADS)

Son, Ho-Young; Kim, Ilho; Lee, Soon-Bok; Jung, Gi-Jo; Park, Byung-Jin; Paik, Kyung-Wook

2009-01-01

A thick Cu column based double-bump flip chip structure is one of the promising alternatives for fine pitch flip chip applications. In this study, the thermal cycling (T/C) reliability of Cu/SnAg double-bump flip chip assemblies was investigated, and the failure mechanism was analyzed through the correlation of T/C test and the finite element analysis (FEA) results. After 1000 thermal cycles, T/C failures occurred at some Cu/SnAg bumps located at the edge and corner of chips. Scanning acoustic microscope analysis and scanning electron microscope observations indicated that the failure site was the Cu column/Si chip interface. It was identified by a FEA where the maximum stress concentration was located during T/C. During T/C, the Al pad between the Si chip and a Cu column bump was displaced due to thermomechanical stress. Based on the low cycle fatigue model, the accumulation of equivalent plastic strain resulted in thermal fatigue deformation of the Cu column bumps and ultimately reduced the thermal cycling lifetime. The maximum equivalent plastic strains of some bumps at the chip edge increased with an increased number of thermal cycles. However, equivalent plastic strains of the inner bumps did not increase regardless of the number of thermal cycles. In addition, the z-directional normal plastic strain ɛ22 was determined to be compressive and was a dominant component causing the plastic deformation of Cu/SnAg double bumps. As the number of thermal cycles increased, normal plastic strains in the perpendicular direction to the Si chip and shear strains were accumulated on the Cu column bumps at the chip edge at low temperature region. Thus it was found that the Al pad at the Si chip/Cu column interface underwent thermal fatigue deformation by compressive normal strain and the contact loss by displacement failure of the Al pad, the main T/C failure mode of the Cu/SnAg flip chip assembly, then occurred at the Si chip/Cu column interface shear strain deformation during T/C.

Leveling up the analysis of the reminiscence bump in autobiographical memory: A new approach based on multilevel multinomial models.

PubMed

Zimprich, Daniel; Wolf, Tabea

2018-06-20

In many studies of autobiographical memory, participants are asked to generate more than one autobiographical memory. The resulting data then have a hierarchical or multilevel structure, in the sense that the autobiographical memories (Level 1) generated by the same person (Level 2) tend to be more similar. Transferred to an analysis of the reminiscence bump in autobiographical memory, at Level 1 the prediction of whether an autobiographical memory will fall within the reminiscence bump is based on the characteristics of that memory. At Level 2, the prediction of whether an individual will report more autobiographical memories that fall in the reminiscence bump is based on the characteristics of the individual. We suggest a multilevel multinomial model that allows for analyzing whether an autobiographical memory falls in the reminiscence bump at both levels of analysis simultaneously. The data come from 100 older participants who reported up to 33 autobiographical memories. Our results showed that about 12% of the total variance was between persons (Level 2). Moreover, at Level 1, memories of first-time experiences were more likely to fall in the reminiscence bump than were emotionally more positive memories. At Level 2, persons who reported more emotionally positive memories tended to report fewer memories from the life period after the reminiscence bump. In addition, cross-level interactions showed that the effects at Level 1 partly depended on the Level 2 effects. We discuss possible extensions of the model we present and the meaning of our findings for two prominent explanatory approaches to the reminiscence bump, as well as future directions.

Design and test of data acquisition systems for the Medipix2 chip based on PC standard interfaces

NASA Astrophysics Data System (ADS)

Fanti, Viviana; Marzeddu, Roberto; Piredda, Giuseppina; Randaccio, Paolo

2005-07-01

We describe two readout systems for hybrid detectors using the Medipix2 single photon counting chip, developed within the Medipix Collaboration. The Medipix2 chip (256×256 pixels, 55 μm pitch) has an active area of about 2 cm 2 and is bump-bonded to a pixel semiconductor array of silicon or other semiconductor material. The readout systems we are developing are based on two widespread standard PC interfaces: parallel port and USB (Universal Serial Bus) version 1.1. The parallel port is the simplest PC interface even if slow and the USB is a serial bus interface present nowadays on all PCs and offering good performances.

Infrared bolometers with silicon nitride micromesh absorbers

NASA Technical Reports Server (NTRS)

Bock, J. J.; Turner, A. D.; DelCastillo, H. M.; Beeman, J. W.; Lange, A. E.; Mauskopf, P. D.

1996-01-01

Sensitive far infrared and millimeter wave bolometers fabricated from a freestanding membrane of low stress silicon nitride are reported. The absorber, consisting of a metallized silicon nitride micromesh thermally isolated by radial legs of silicon nitride, is placed in an integrating cavity to efficiently couple to single mode or multiple mode infrared radiation. This structure provides low heat capacity, low thermal conduction and minimal cross section to energetic particles. A neutron transmutation doped Ge thermister is bump bonded to the center of the device and read out with evaporated Cr-Au leads. The limiting performance of the micromesh absorber is discussed and the recent results obtained from a 300 mK cold stage are summarized.

The Physics of Bump Drafting in Car Racing

ERIC Educational Resources Information Center

Fiolhais, Miguel C. N.; Amor dos Santos, Susana

2014-01-01

The technique of bump drafting, also known as two-car drafting in motorsports, is analysed in the framework of Newtonian mechanics and simple aerodynamic drag forces. As an apparent unnatural effect that often pleases the enthusiasts of car racing, bump drafting provides a unique pedagogical opportunity for students to gain insights into the…

Life scripts for emotionally charged autobiographical memories: A cultural explanation of the reminiscence bump.

PubMed

Haque, Shamsul; Hasking, Penelope A

2010-10-01

Two studies examined the ability of the life script account to explain the reminiscence bump for emotionally charged autobiographical memories among Malaysian participants. In Study 1 volunteers, aged 50-90 years, participated in a two-phased task. In the first phase, participants estimated the timing of 11 life events (both positive and negative) that may occur in a prototypical life course within their own culture. Two weeks later the participants retrieved the same set of events from their lives and reported how old they were when those events occurred. In the second study 92 undergraduate students produced life scripts for the same 11 events. The findings revealed reminiscence bumps in both life script and retrieval curves for the memories judged happiest, most important, most in love, and most jealous. A reminiscence bump was also noted for success, although this was later in the lifespan than other reminiscence bumps. It was suggested that the life scripts can be used as an alternative account for the reminiscence bump, for highly positive and occasionally for negative autobiographical memories.

Fission gas release during power bumping at high burnup

NASA Astrophysics Data System (ADS)

Cunningham, M. E.; Freshley, M. D.; Lanning, D. D.

1993-03-01

Research to define the behavior of Zircaloy-clad light-water reactor fuel irradiated to high burnup levels was conducted by the High Burnup Effects Program (HBEP). One activity conducted by the HBEP was to "bump" the power level of irradiated, commercial light-water reactor fuel rods to design limit linear heat generation rates at end-of-life. These bumping irradiations simulated end-of-life design limit linear heat generation rates and provided data on the effects of short-term, high power irradiations at high burnup applicable to the design and operating constraints imposed by maximum allowable fuel rod internal gas pressure limits. Based on net fission gas release during the bumping irradiations, it was observed that higher burnup rods had greater rod-average fractional fission gas release than lower burnup rods at equal bumping powers. It was also observed that a hold period of 48 hours at the peak power was insufficient to achieve equilibrium fission gas release. Finally, differences in the prebump location of fission gas, i.e., within the UO 2 matrix or at grain boundaries, affected the fission gas release during the bumping irradiations.

Design and characterization of the ePix10k: a high dynamic range integrating pixel ASIC for LCLS detectors

NASA Astrophysics Data System (ADS)

Caragiulo, P.; Dragone, A.; Markovic, B.; Herbst, R.; Nishimura, K.; Reese, B.; Herrmann, S.; Hart, P.; Blaj, G.; Segal, J.; Tomada, A.; Hasi, J.; Carini, G.; Kenney, C.; Haller, G.

2015-05-01

ePix10k is a variant of a novel class of integrating pixel ASICs architectures optimized for the processing of signals in second generation LINAC Coherent Light Source (LCLS) X-Ray cameras. The ASIC is optimized for high dynamic range application requiring high spatial resolution and fast frame rates. ePix ASICs are based on a common platform composed of a random access analog matrix of pixel with global shutter, fast parallel column readout, and dedicated sigma-delta analog to digital converters per column. The ePix10k variant has 100um×100um pixels arranged in a 176×192 matrix, a resolution of 140e- r.m.s. and a signal range of 3.5pC (10k photons at 8keV). In its final version it will be able to sustain a frame rate of 2kHz. A first prototype has been fabricated and characterized. Performance in terms of noise, linearity, uniformity, cross-talk, together with preliminary measurements with bump bonded sensors are reported here.

Backshort-Under-Grid arrays for infrared astronomy

NASA Astrophysics Data System (ADS)

Allen, C. A.; Benford, D. J.; Chervenak, J. A.; Chuss, D. T.; Miller, T. M.; Moseley, S. H.; Staguhn, J. G.; Wollack, E. J.

2006-04-01

We are developing a kilopixel, filled bolometer array for space infrared astronomy. The array consists of three individual components, to be merged into a single, working unit; (1) a transition edge sensor bolometer array, operating in the milliKelvin regime, (2) a quarter-wave backshort grid, and (3) superconducting quantum interference device multiplexer readout. The detector array is designed as a filled, square grid of suspended, silicon bolometers with superconducting sensors. The backshort arrays are fabricated separately and will be positioned in the cavities created behind each detector during fabrication. The grids have a unique interlocking feature machined into the walls for positioning and mechanical stability. The spacing of the backshort beneath the detector grid can be set from ˜30 300 μm, by independently adjusting two process parameters during fabrication. The ultimate goal is to develop a large-format array architecture with background-limited sensitivity, suitable for a wide range of wavelengths and applications, to be directly bump bonded to a multiplexer circuit. We have produced prototype two-dimensional arrays having 8×8 detector elements. We present detector design, fabrication overview, and assembly technologies.

Geometrical and Structural Asperities on Fault Surfaces

NASA Astrophysics Data System (ADS)

Sagy, A.; Brodsky, E. E.; van der Elst, N.; Agosta, F.; di Toro, G.; Collettini, C.

2007-12-01

Earthquake dynamics are strongly affected by fault zone structure and geometry. Fault surface irregularities and the nearby structure control the rupture nucleation and propagation, the fault strength, the near-field stress orientations and the hydraulic properties. New field observations demonstrate the existence of asperities in faults as displayed by topographical bumps on the fault surface and hardening of the internal structure near them. Ground-based LIDAR measurements on more than 30 normal and strike slip faults in different lithologies demonstrate that faults are not planar surfaces and roughness is strongly dependent on fault displacement. In addition to the well-understood roughness exemplified by abrasive striations and fracture segmentation, we found semi-elliptical topographical bumps with wavelengths of a few meters. In many faults the bumps are not spread equally on the surface and zones can be bumpier than others. The bumps are most easily identified on faults with total displacement of dozens to hundreds of meters. Smaller scale roughness on these faults is smoothed by abrasive processes. A key site in southern Oregon shows that the topographic bumps are closely tied to the internal structure of the fault zone. At this location, we combine LiDAR data with detailed structural analysis of the fault zone embedded in volcanic rocks. Here the bumps correlate with an abrupt change in the width of the cohesive cataclasite layer that is exposed under a thin ultracataclasite zone. In most of the exposures the cohesive layer thickness is 10-20 cm. However, under protruding bumps the layer is always thickened and the width can locally exceed one meter. Field and microscopic analyses show that the layer contains grains with dimensions ranging from less than 10 μ up to a few centimeters. There is clear evidence of internal flow, rotation and fracturing of the grains in the layer. X-Ray diffraction measurements of samples from the layer show that the bulk mineralogy is identical to that of the host rock, although thin section analysis suggests that some alteration and secondary mineralization of the grains also occurs. We infer that the cohesiveness of the layer is a consequence of repacking and cementation similar to deformation bands in granular material. By comparing the thickness of the cohesive layer on several secondary faults in this fault area we found that the average thickness of the layer increases with total slip. The correlation is nonlinear and the thickening rate decreases with increasing slip. We conclude that granular flow decreasing with increasing slip and thus the deformation is continually localized.

Effect of Grain Boundary Misorientation on Electromigration in Lead-Free Solder Joints

NASA Astrophysics Data System (ADS)

Tasooji, Amaneh; Lara, Leticia; Lee, Kyuoh

2014-12-01

Reduction in microelectronic interconnect size gives rise to solder bumps consisting of few grains, approaching a single- or bicrystal grain morphology in C4 bumps. Single grain anisotropy, individual grain orientation, presence of easy diffusion paths along grain boundaries, and the increased current density in these small solder bumps aggravate electromigration. This reduces the reliability of the entire microelectronic system. This paper focuses on electromigration behavior in Pb-free solder, specifically the Sn-0.7 wt.%Cu alloy. We discuss the effects of texture, grain orientation, and grain boundary misorientation angle on electromigration (EM) and intermetallic compound formation in EM-tested C4 bumps. The detailed electron backscatter diffraction (EBSD) analysis used in this study reveals the greater influence of grain boundary misorientation on solder bump electromigration compared with the effect associated with individual grain orientation.

Cost-effective method of manufacturing a 3D MEMS optical switch

NASA Astrophysics Data System (ADS)

Carr, Emily; Zhang, Ping; Keebaugh, Doug; Chau, Kelvin

2009-02-01

growth of data and video transport networks. All-optical switching eliminates the need for optical-electrical conversion offering the ability to switch optical signals transparently: independent of data rates, formats and wavelength. It also provides network operators much needed automation capabilities to create, monitor and protect optical light paths. To further accelerate the market penetration, it is necessary to identify a path to reduce the manufacturing cost significantly as well as enhance the overall system performance, uniformity and reliability. Currently, most MEMS optical switches are assembled through die level flip-chip bonding with either epoxies or solder bumps. This is due to the alignment accuracy requirements of the switch assembly, defect matching of individual die, and cost of the individual components. In this paper, a wafer level assembly approach is reported based on silicon fusion bonding which aims to reduce the packaging time, defect count and cost through volume production. This approach is successfully demonstrated by the integration of two 6-inch wafers: a mirror array wafer and a "snap-guard" wafer, which provides a mechanical structure on top of the micromirror to prevent electrostatic snap-down. The direct silicon-to-silicon bond eliminates the CTEmismatch and stress issues caused by non-silicon bonding agents. Results from a completed integrated switch assembly will be presented, which demonstrates the reliability and uniformity of some key parameters of this MEMS optical switch.

Flexible Chip Scale Package and Interconnect for Implantable MEMS Movable Microelectrodes for the Brain

PubMed Central

Jackson, Nathan; Muthuswamy, Jit

2009-01-01

We report here a novel approach called MEMS microflex interconnect (MMFI) technology for packaging a new generation of Bio-MEMS devices that involve movable microelectrodes implanted in brain tissue. MMFI addresses the need for (i) operating space for movable parts and (ii) flexible interconnects for mechanical isolation. We fabricated a thin polyimide substrate with embedded bond-pads, vias, and conducting traces for the interconnect with a backside dry etch, so that the flexible substrate can act as a thin-film cap for the MEMS package. A double gold stud bump rivet bonding mechanism was used to form electrical connections to the chip and also to provide a spacing of approximately 15–20 µm for the movable parts. The MMFI approach achieved a chip scale package (CSP) that is lightweight, biocompatible, having flexible interconnects, without an underfill. Reliability tests demonstrated minimal increases of 0.35 mΩ, 0.23 mΩ and 0.15 mΩ in mean contact resistances under high humidity, thermal cycling, and thermal shock conditions respectively. High temperature tests resulted in an increase in resistance of > 90 mΩ when aluminum bond pads were used, but an increase of ~ 4.2 mΩ with gold bond pads. The mean-time-to-failure (MTTF) was estimated to be at least one year under physiological conditions. We conclude that MMFI technology is a feasible and reliable approach for packaging and interconnecting Bio-MEMS devices. PMID:20160981

Dropwise condensation on hydrophobic bumps and dimples

NASA Astrophysics Data System (ADS)

Yao, Yuehan; Aizenberg, Joanna; Park, Kyoo-Chul

2018-04-01

Surface topography plays an important role in promoting or suppressing localized condensation. In this work, we study the growth of water droplets on hydrophobic convex surface textures such as bumps and concave surface textures such as dimples with a millimeter scale radius of curvature. We analyze the spatio-temporal droplet size distribution under a supersaturation condition created by keeping the uniform surface temperature below the dew point and show its relationship with the sign and magnitude of the surface curvature. In particular, in contrast to the well-known capillary condensation effect, we report an unexpectedly less favorable condensation on smaller, millimeter-scale dimples where the capillary condensation effect is negligible. To explain these experimental results, we numerically calculated the diffusion flux of water vapor around the surface textures, showing that its magnitude is higher on bumps and lower on dimples compared to a flat surface. We envision that our understanding of millimetric surface topography can be applied to improve the energy efficiency of condensation in applications such as water harvesting, heating, ventilation, and air conditioning systems for buildings and transportation, heat exchangers, thermal desalination plants, and fuel processing systems.

Experimental study of the energy dependence of the total cross section for the 6He + natSi and 9Li + natSi reactions

NASA Astrophysics Data System (ADS)

Sobolev, Yu. G.; Penionzhkevich, Yu. E.; Aznabaev, D.; Zemlyanaya, E. V.; Ivanov, M. P.; Kabdrakhimova, G. D.; Kabyshev, A. M.; Knyazev, A. G.; Kugler, A.; Lashmanov, N. A.; Lukyanov, K. V.; Maj, A.; Maslov, V. A.; Mendibayev, K.; Skobelev, N. K.; Slepnev, R. S.; Smirnov, V. V.; Testov, D.

2017-11-01

New experimental measurements of the total reaction cross sections for the 6He + natSi and 9Li + natSi processes in the energy range of 5 to 40 A MeV are presented. A modified transmission method based on high-efficiency detection of prompt n-γ radiation has been used in the experiment. A bump is observed for the first time in the energy dependence σR( E) at E ˜ 10-30 A MeV for the 9Li + natSi reaction, and existence of the bump in σR( E) at E ˜ 10-20 A MeV first observed in the standard transmission experiments is experimentally confirmed for the 6He + natSi reaction. Theoretical analysis of the measured 6He + natSi and 9Li + natSi reaction cross sections is performed within the microscopic double folding model. Disagreement is observed between the experimental and theoretical cross sections in the region of the bump at the energies of 10 to 20 A MeV, which requires further study.

Bumping into Someone: Japanese Students' Perceptions and Observations

ERIC Educational Resources Information Center

Lieske, Carmella

2010-01-01

This pilot study explores the apologies Japanese nursing college students thought they would use in their L1 (i.e. Japanese) and their L2 (i.e. English) when bumping into each other. The students completed a questionnaire, the results of which indicated that they believed they should always apologize for bumping into someone. The paper describes…

Structural Joint with Multi-Axis Load Carrying Capability

NASA Technical Reports Server (NTRS)

Wu, K. Chauncey (Inventor); Martin, Robert A. (Inventor); Stewart, Brian K. (Inventor)

2017-01-01

A structural joint is formed of a mandrel having a plurality of bumps and dimples formed thereon which is fitted into a sleeve. The bumps and dimples form a non-circular geometry at all points along the length of the mandrel. The bumps are defined by surfaces which have 1st and 2nd derivatives which are continuous.

Modification of Bushing Test Rig and Research of Variable Inlet Guide Vane Bushings For Further Development of PM304 Bushings

NASA Technical Reports Server (NTRS)

Yanke, Anne

2004-01-01

PS304 is a high temperature solid lubricant coating comprised of a nickel-chrome binder, chrome oxide hardener, barium-calcium fluoride high temperature lubricant, and silver as the low temperature lubricant. This coating is used to lubricate Oil-Free Foil Air Bearings as they experience friction and wear during start up and shut down. The coating deposition process begins with undercutting the shaft. This area is then sandblasted to provide a rough surface for the coating to adhere to. The coating powder is then sent through the plasma spray gun and a reasonably thick layer is applied to the undercut area of the shaft. The coating is then ground down even with the surface of the shaft and gets a nice polished finish. The foil air bearings use the solid lubricant, as mentioned above, during start up and shut down. During normal operating conditions, generally above 2000RPM, the bearings utilize air as their lubricant. Foil air bearings are comprised of a thin top foil and a corrugated bump foil. They have an interference fit with the shaft before operation. As the air gets "trapped" between the top foil and the shaft, it presses the top foil against the bump foil, in turn compressing the bumps. As the bumps compress, it allows for the air to separate the top foil from the shaft, therefore, utilizing the trapped air as its lubricant.

Revisiting the emission from relativistic blast waves in a density-jump medium

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

Geng, J. J.; Huang, Y. F.; Dai, Z. G.

2014-09-01

Re-brightening bumps are frequently observed in gamma-ray burst afterglows. Many scenarios have been proposed to interpret the origin of these bumps, of which a blast wave encountering a density-jump in the circumburst environment has been questioned by recent works. We develop a set of differential equations to calculate the relativistic outflow encountering the density-jump by extending the work of Huang et al. This approach is a semi-analytic method and is very convenient. Our results show that late high-amplitude bumps cannot be produced under common conditions, rather only a short plateau may emerge even when the encounter occurs at an earlymore » time (<10{sup 4} s). In general, our results disfavor the density-jump origin for those observed bumps, which is consistent with the conclusion drawn from full hydrodynamics studies. The bumps thus should be caused by other scenarios.« less

Results from the NA62 Gigatracker Prototype: A Low-Mass and sub-ns Time Resolution Silicon Pixel Detector

NASA Astrophysics Data System (ADS)

Fiorini, M.; Rinella, G. Aglieri; Carassiti, V.; Ceccucci, A.; Gil, E. Cortina; Ramusino, A. Cotta; Dellacasa, G.; Garbolino, S.; Jarron, P.; Kaplon, J.; Kluge, A.; Marchetto, F.; Mapelli, A.; Martin, E.; Mazza, G.; Morel, M.; Noy, M.; Nuessle, G.; Petagna, P.; Petrucci, F.; Perktold, L.; Riedler, P.; Rivetti, A.; Statera, M.; Velghe, B.

The Gigatracker (GTK) is a hybrid silicon pixel detector developed for NA62, the experiment aimed at studying ultra-rare kaon decays at the CERN SPS. Three GTK stations will provide precise momentum and angular measurements on every track of the high intensity NA62 hadron beam with a time-tagging resolution of 150 ps. Multiple scattering and hadronic interactions of beam particles in the GTK have to be minimized to keep background events at acceptable levels, hence the total material budget is fixed to 0.5% X0 per station. In addition the calculated fluence for 100 days of running is 2×1014 1 MeV neq/cm2, comparable to the one expected for the inner trackers of LHC detectors in 10 years of operation. These requirements pose challenges for the development of an efficient and low-mass cooling system, to be operated in vacuum, and on the thinning of read-out chips to 100 μm or less. The most challenging requirement is represented by the time resolution, which can be achieved by carefully compensating for the discriminator time-walk. For this purpose, two complementary read-out architectures have been designed and produced as small-scale prototypes: the first is based on the use of a Time-over-Threshold circuit followed by a TDC shared by a group of pixels, while the other uses a constant-fraction discriminator followed by an on-pixel TDC. The readout pixel ASICs are produced in 130 nm IBM CMOS technology and bump-bonded to 200 μm thick silicon sensors. The Gigatracker detector system is described with particular emphasis on recent experimental results obtained from laboratory and beam tests of prototype bump-bonded assemblies, which show a time resolution of less than 200 ps for single hits.

Simulation studies of plasma waves in the electron foreshock - The generation of downshifted oscillations

NASA Technical Reports Server (NTRS)

Dum, C. T.

1990-01-01

The generation of waves with frequencies downshifted from the plasma frequency, as observed in the electron foreshock, is analyzed by particle simulation. Wave excitation differs fundamentally from the familiar excitation of the plasma eigenmodes by a gentle bump-on-tail electron distribution. Beam modes are destabilized by resonant interaction with bulk electrons, provided the beam velocity spread is very small. These modes are stabilized, starting with the higher frequencies, as the beam is broadened and slowed down by the interaction with the wave spectrum. Initially a very cold beam is also capable of exciting frequencies considerably above the plasma frequency, but such oscillations are quickly stabilized. Low-frequency modes persist for a long time, until the bump in the electron distribution is completely 'ironed' out. This diffusion process also is quite different from the familiar case of well-separated beam and bulk electrons. A quantitative analysis of these processes is carried out.

An experimental and theoretical study of structural damping in compliant foil bearings

NASA Technical Reports Server (NTRS)

Ku, C.-P. Roger

1994-01-01

This paper describes an experimental investigation into the dynamic characteristics of corrugated foil (bump foil) strips used in compliant surface foil bearings. This study provided and opportunity to quantify the structural damping of bump foil strips. The experimental data were compared to results obtained by a theoretical model developed earlier. The effects of bearing design parameters, such as static loads, dynamic displacement amplitudes, bump configurations, pivot locations, surface coatings, and lubricant were also evaluated. An understanding of the dynamic characteristics of bump foil strips resulting from this work offers designers a means for enhancing the design of high-performance compliant foil bearings.

The velocity field created by a shallow bump in a boundary layer

NASA Technical Reports Server (NTRS)

Gaster, Michael; Grosch, Chester E.; Jackson, Thomas L.

1994-01-01

We report the results of measurements of the disturbance velocity field generated in a boundary layer by a shallow three-dimensional bump oscillating at a very low frequency on the surface of a flat plate. Profiles of the mean velocity, the disturbance velocity at the fundamental frequency and at the first harmonic are presented. These profiles were measured both upstream and downstream of the oscillating bump. Measurements of the disturbance velocity were also made at various spanwise and downstream locations at a fixed distance from the boundary of one displacement thickness. Finally, the spanwise spectrum of the disturbances at three locations downstream of the bump are presented.

Thermal conductivity on stud bump interconnection of high power COB LED

NASA Astrophysics Data System (ADS)

Sarukunaselan, K.; Ong, N. R.; Sauli, Z.; Mahmed, N.; Kirtsaeng, S.; Sakuntasathien, S.; Suppiah, S.; Alcain, J. B.; Retnasamy, V.

2017-09-01

In this paper, the impacts of bump dimensions and material conductivity on the thermal performances of a high power chip on board (COB) LED package were investigated using open source software, Elmer. The stud bump acted as interconnection join which has an extra role in dissipating heat generated by the chip to the ambience. Simulation data showed that for a bump with a fixed contact length of 1mm, the most suitable height was 171 µm with material conductivity of 238W/mK or 319W/mK. Materials with thermal conductivity of lower than 20W/mK, had the poorest heat dissipation irrespective of the height.

Point process analysis of noise in early invertebrate vision

PubMed Central

Vinnicombe, Glenn

2017-01-01

Noise is a prevalent and sometimes even dominant aspect of many biological processes. While many natural systems have adapted to attenuate or even usefully integrate noise, the variability it introduces often still delimits the achievable precision across biological functions. This is particularly so for visual phototransduction, the process responsible for converting photons of light into usable electrical signals (quantum bumps). Here, randomness of both the photon inputs (regarded as extrinsic noise) and the conversion process (intrinsic noise) are seen as two distinct, independent and significant limitations on visual reliability. Past research has attempted to quantify the relative effects of these noise sources by using approximate methods that do not fully account for the discrete, point process and time ordered nature of the problem. As a result the conclusions drawn from these different approaches have led to inconsistent expositions of phototransduction noise performance. This paper provides a fresh and complete analysis of the relative impact of intrinsic and extrinsic noise in invertebrate phototransduction using minimum mean squared error reconstruction techniques based on Bayesian point process (Snyder) filters. An integrate-fire based algorithm is developed to reliably estimate photon times from quantum bumps and Snyder filters are then used to causally estimate random light intensities both at the front and back end of the phototransduction cascade. Comparison of these estimates reveals that the dominant noise source transitions from extrinsic to intrinsic as light intensity increases. By extending the filtering techniques to account for delays, it is further found that among the intrinsic noise components, which include bump latency (mean delay and jitter) and shape (amplitude and width) variance, it is the mean delay that is critical to noise performance. As the timeliness of visual information is important for real-time action, this delay could potentially limit the speed at which invertebrates can respond to stimuli. Consequently, if one wants to increase visual fidelity, reducing the photoconversion lag is much more important than improving the regularity of the electrical signal. PMID:29077703

Gallium arsenide quantum well-based far infrared array radiometric imager

NASA Technical Reports Server (NTRS)

Forrest, Kathrine A.; Jhabvala, Murzy D.

1991-01-01

We have built an array-based camera (FIRARI) for thermal imaging (lambda = 8 to 12 microns). FIRARI uses a square format 128 by 128 element array of aluminum gallium arsenide quantum well detectors that are indium bump bonded to a high capacity silicon multiplexer. The quantum well detectors offer good responsivity along with high response and noise uniformity, resulting in excellent thermal images without compensation for variation in pixel response. A noise equivalent temperature difference of 0.02 K at a scene temperature of 290 K was achieved with the array operating at 60 K. FIRARI demonstrated that AlGaAS quantum well detector technology can provide large format arrays with performance superior to mercury cadmium telluride at far less cost.

A comprehensive experimental characterization of the iPIX gamma imager

NASA Astrophysics Data System (ADS)

Amgarou, K.; Paradiso, V.; Patoz, A.; Bonnet, F.; Handley, J.; Couturier, P.; Becker, F.; Menaa, N.

2016-08-01

The results of more than 280 different experiments aimed at exploring the main features and performances of a newly developed gamma imager, called iPIX, are summarized in this paper. iPIX is designed to quickly localize radioactive sources while estimating the ambient dose equivalent rate at the measurement point. It integrates a 1 mm thick CdTe detector directly bump-bonded to a Timepix chip, a tungsten coded-aperture mask, and a mini RGB camera. It also represents a major technological breakthrough in terms of lightness, compactness, usability, response sensitivity, and angular resolution. As an example of its key strengths, an 241Am source with a dose rate of only few nSv/h can be localized in less than one minute.

Cross-Validation of Survival Bump Hunting by Recursive Peeling Methods.

PubMed

Dazard, Jean-Eudes; Choe, Michael; LeBlanc, Michael; Rao, J Sunil

2014-08-01

We introduce a survival/risk bump hunting framework to build a bump hunting model with a possibly censored time-to-event type of response and to validate model estimates. First, we describe the use of adequate survival peeling criteria to build a survival/risk bump hunting model based on recursive peeling methods. Our method called "Patient Recursive Survival Peeling" is a rule-induction method that makes use of specific peeling criteria such as hazard ratio or log-rank statistics. Second, to validate our model estimates and improve survival prediction accuracy, we describe a resampling-based validation technique specifically designed for the joint task of decision rule making by recursive peeling (i.e. decision-box) and survival estimation. This alternative technique, called "combined" cross-validation is done by combining test samples over the cross-validation loops, a design allowing for bump hunting by recursive peeling in a survival setting. We provide empirical results showing the importance of cross-validation and replication.

Cross-Validation of Survival Bump Hunting by Recursive Peeling Methods

PubMed Central

Dazard, Jean-Eudes; Choe, Michael; LeBlanc, Michael; Rao, J. Sunil

2015-01-01

We introduce a survival/risk bump hunting framework to build a bump hunting model with a possibly censored time-to-event type of response and to validate model estimates. First, we describe the use of adequate survival peeling criteria to build a survival/risk bump hunting model based on recursive peeling methods. Our method called “Patient Recursive Survival Peeling” is a rule-induction method that makes use of specific peeling criteria such as hazard ratio or log-rank statistics. Second, to validate our model estimates and improve survival prediction accuracy, we describe a resampling-based validation technique specifically designed for the joint task of decision rule making by recursive peeling (i.e. decision-box) and survival estimation. This alternative technique, called “combined” cross-validation is done by combining test samples over the cross-validation loops, a design allowing for bump hunting by recursive peeling in a survival setting. We provide empirical results showing the importance of cross-validation and replication. PMID:26997922

Coincidence avoidance principle in surface haptic interpretation

PubMed Central

Manuel, Steven G.; Klatzky, Roberta L.; Peshkin, Michael A.; Colgate, James Edward

2015-01-01

When multiple fingertips experience force sensations, how does the brain interpret the combined sensation? In particular, under what conditions are the sensations perceived as separate or, alternatively, as an integrated whole? In this work, we used a custom force-feedback device to display force signals to two fingertips (index finger and thumb) as they traveled along collinear paths. Each finger experienced a pattern of forces that, taken individually, produced illusory virtual bumps, and subjects reported whether they felt zero, one, or two bumps. We varied the spatial separation between these bump-like force-feedback regions, from being much greater than the finger span to nearly exactly the finger span. When the bump spacing was the same as the finger span, subjects tended to report only one bump. We found that the results are consistent with a quantitative model of perception in which the brain selects a structural interpretation of force signals that relies on minimizing coincidence stemming from accidental alignments between fingertips and inferred surface structures. PMID:25675477

Comedones

MedlinePlus

Skin bumps - acne-like; Acne-like skin bumps; Whiteheads; Blackheads ... of cutaneous appendages. In: Patterson JW, ed. Weedon's Skin Pathology . 4th ed. Philadelphia, PA: Elsevier Churchill Livingstone; ...

Dynamic traversal of high bumps and large gaps by a small legged robot

NASA Astrophysics Data System (ADS)

Gart, Sean; Winey, Nastasia; de La Tijera Obert, Rafael; Li, Chen

Small animals encounter and negotiate diverse obstacles comparable in size or larger than themselves. In recent experiments, we found that cockroaches can dynamically traverse bumps up to 4 times hip height and gaps up to 1 body length. To better understand the physics that governs these locomotor transitions, we studied a small six-legged robot negotiating high bumps and large gaps and compared it to animal observations. We found that the robot was able to traverse bumps as large as 1 hip height and gaps as wide as 0.5 body length. For the bump, the robot often climbed over to traverse when initial body yaw was small, but was often deflected laterally and failed to traverse when initial body yaw was large. A simple locomotion energy landscape model explained these observations. For the gap, traversal probability decreased with gap width, which was well explained by a simple Lagrangian model of a forward-moving rigid body falling over the gap edge. For both the bump and the gap, animal performance far exceeded that of the robot, likely due to their relatively higher running speeds and larger rotational oscillations prior to and during obstacle traversal. Differences between animal and robot obstacle negotiation behaviors revealed that animals used active strategies to overcome potential energy barriers.

A new modal-based approach for modelling the bump foil structure in the simultaneous solution of foil-air bearing rotor dynamic problems

NASA Astrophysics Data System (ADS)

Bin Hassan, M. F.; Bonello, P.

2017-05-01

Recently-proposed techniques for the simultaneous solution of foil-air bearing (FAB) rotor dynamic problems have been limited to a simple bump foil model in which the individual bumps were modelled as independent spring-damper (ISD) subsystems. The present paper addresses this limitation by introducing a modal model of the bump foil structure into the simultaneous solution scheme. The dynamics of the corrugated bump foil structure are first studied using the finite element (FE) technique. This study is experimentally validated using a purpose-made corrugated foil structure. Based on the findings of this study, it is proposed that the dynamics of the full foil structure, including bump interaction and foil inertia, can be represented by a modal model comprising a limited number of modes. This full foil structure modal model (FFSMM) is then adapted into the rotordynamic FAB problem solution scheme, instead of the ISD model. Preliminary results using the FFSMM under static and unbalance excitation conditions are proven to be reliable by comparison against the corresponding ISD foil model results and by cross-correlating different methods for computing the deflection of the full foil structure. The rotor-bearing model is also validated against experimental and theoretical results in the literature.

Properties of Dust Obscured Galaxies in the Nep-Deep Field

NASA Astrophysics Data System (ADS)

Oi, Nagisa; Matsuhara, Hideo; Pearson, Chris; Buat, Veronique; Burgarella, Denis; Malkan, Matt; Miyaji, Takamitsu; AKARI-NEP Team

2017-03-01

We selected 47 DOGs at z∼1.5 using optical R (or r^{'}), AKARI 18 μm, and 24 μm color in the AKARI North Ecliptic Pole (NEP) Deep survey field. Using the colors among 3, 4, 7, and 9μm, we classified them into 3 groups; bump DOGs (23 sources), power-law DOGs (16 sources), and unknown DOGs (8 sources). We built spectral energy distributions (SEDs) with optical to far-infrared photometric data and investigated their properties using SED fitting method. We found that AGN activity such as a AGN contribution to the infrared luminosity and a Chandra detection rate for bump and power-law DOGs are significantly different, while stellar component properties like a stellar mass and a star-formation rate are similar to each other. A specific star-formation rate range of power-law DOGs is slightly higher than that of bump DOGs with wide overlap. Herschel/PACS detection rates are almost the same between bump and power-law DOGs. On the other hand SPIRE detection rates show large differences between bump and power-law DOGs. These results might be explained by differences in dust temperatures. Both groups of DOGs host hot and/or warm dust (∼ 50 Kelvin), and many bump DOGs contain cooler dust (≤ 30 Kelvin)

Life-span retrieval of public events: Reminiscence bump for high-impact events, recency for others.

PubMed

Tekcan, Ali I; Boduroglu, Aysecan; Mutlutürk, Aysu; Aktan Erciyes, Aslı

2017-10-01

Although substantial evidence exists showing a reliable reminiscence bump for personal events, data regarding retrieval distributions for public events have been equivocal. The primary aim of the present study was to address life-span retrieval distributions of different types of public events in comparison to personal events, and to test whether the existing accounts of the bump can explain the distribution of public events. We asked a large national sample to report the most important, happiest, and saddest personal events and the most important, happiest, saddest, most proud, most fearful, and most shameful public events. We found a robust bump corresponding to the third decade of life for the happiest and the most important positive but not for the saddest and most important negative personal events. For the most important public events, a bump emerged only for the two most frequently mentioned events. Distributions of public events cued with emotions were marked by recency. These results point to potential differences in retrieval of important personal and public events. While the life-script framework well accounts for the findings regarding important personal events, a chronologically retroactive search seem to guide retrieval of public events. Reminiscence bump observed for the two public events suggest that age-at-event affects recall of public events to the degree that the events are high-impact ones that dominate nation's collective memory. Results provide further evidence that the bump is not unitary and points to importance of event type and memory elicitation method with regard to competing explanations of the phenomenon.

TOWARD DETECTING THE 2175 A DUST FEATURE ASSOCIATED WITH STRONG HIGH-REDSHIFT Mg II ABSORPTION LINES

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

Jiang Peng; Zhou Hongyan; Wang Junxian

2011-05-10

We report detections of 39 2175 A dust extinction bump candidates associated with strong Mg II absorption lines at z{approx} 1-1.8 on quasar spectra in Sloan Digital Sky Survey (SDSS) DR3. These strong Mg II absorption line systems are detected among 2951 strong Mg II absorbers with a rest equivalent width W{sub r} {lambda}2796> 1.0 A at 1.0 < z < 1.86, which is part of a full sample of 7421 strong Mg II absorbers compiled by Prochter et al. The redshift range of the absorbers is chosen to allow the 2175 A extinction features to be completely covered withinmore » the SDSS spectrograph operation wavelength range. An upper limit of the background quasar emission redshift at z = 2.1 is set to prevent the Ly{alpha} forest lines from contaminating the sensitive spectral region for the 2175 A bump measurements. The FM90 parameterization is applied to model the optical/UV extinction curve in the rest frame of Mg II absorbers of the 2175 A bump candidates. The simulation technique developed by Jiang et al. is used to derive the statistical significance of the candidate 2175 A bumps. A total of 12 absorbers are detected with 2175 A bumps at a 5{sigma} level of statistical significance, 10 are detected at a 4{sigma} level, and 17 are detected at a 3{sigma} level. Most of the candidate bumps in this work are similar to the relatively weak 2175 A bumps observed in the Large Magellanic Cloud LMC2 supershell rather than the strong ones observed in the Milky Way. This sample has greatly increased the total number of 2175 A extinction bumps measured on SDSS quasar spectra. Follow-up observations may rule out some of the possible false detections and reveal the physical and chemical natures of 2175 A quasar absorbers.« less

Probing the physics of newly born magnetars through observation of superluminous supernovae

NASA Astrophysics Data System (ADS)

Cheng, Quan; Zhang, Shuang-Nan; Yu, Yun-Wei; Zheng, Xiao-Ping

2018-05-01

The central engines of some superluminous supernovae (SLSNe) are generally suggested to be newly born fast rotating magnetars, which spin down mainly through magnetic dipole radiation and gravitational wave emission. We calculate the magnetar-powered SLSNe light curves (LCs) with the tilt angle evolution of newly born magnetars involved. We show that, depending on the internal toroidal magnetic fields B¯t, the initial spin periods Pi, and the radii RDU of direct Urca (DU) cores of newly born magnetars, as well as the critical temperature Tc for 3P2 neutron superfluidity, bumps could appear in the SLSNe LCs after the maximum lights when the tilt angles grow to π /2 . The value of Tc determines the arising time and the relative amplitude of a bump. The quantity RDU can affect the arising time and the luminosity of a bump, as well as the peak luminosity of a LC. For newly born magnetars with dipole magnetic fields Bd=5 ×1014 G , B¯t=4.6 ×1016 G , and Pi=1 ms , there are no bumps in the LCs if Tc=2 ×109 K , or RDU=1.5 ×105 cm . Moreover, it is interesting that a stronger B¯t will lead to both a brighter peak and a brighter bump in a LC. While keeping other quantities unchanged, the bump in the LC disappears for the magnetar with smaller Pi. We suggest that, once the SLSNe LCs with such kinds of bumps are observed, by fitting these LCs with our model, not only Bd and Pi of newly born magnetars but also the crucial physical quantities B¯t, RDU, and Tc could be determined. Nonobservation of SLSNe LCs with such kinds of bumps hitherto may already put some (though very rough) constraints on B¯t, Pi, RDU, and Tc. Therefore, observation of SLSNe LCs may provide a new approach to probe the physics of newly born magnetars.

Toward Detecting the 2175 Å Dust Feature Associated with Strong High-redshift Mg II Absorption Lines

NASA Astrophysics Data System (ADS)

Jiang, Peng; Ge, Jian; Zhou, Hongyan; Wang, Junxian; Wang, Tinggui

2011-05-01

We report detections of 39 2175 Å dust extinction bump candidates associated with strong Mg II absorption lines at z~ 1-1.8 on quasar spectra in Sloan Digital Sky Survey (SDSS) DR3. These strong Mg II absorption line systems are detected among 2951 strong Mg II absorbers with a rest equivalent width Wr λ2796> 1.0 Å at 1.0 < z < 1.86, which is part of a full sample of 7421 strong Mg II absorbers compiled by Prochter et al. The redshift range of the absorbers is chosen to allow the 2175 Å extinction features to be completely covered within the SDSS spectrograph operation wavelength range. An upper limit of the background quasar emission redshift at z = 2.1 is set to prevent the Lyα forest lines from contaminating the sensitive spectral region for the 2175 Å bump measurements. The FM90 parameterization is applied to model the optical/UV extinction curve in the rest frame of Mg II absorbers of the 2175 Å bump candidates. The simulation technique developed by Jiang et al. is used to derive the statistical significance of the candidate 2175 Å bumps. A total of 12 absorbers are detected with 2175 Å bumps at a 5σ level of statistical significance, 10 are detected at a 4σ level, and 17 are detected at a 3σ level. Most of the candidate bumps in this work are similar to the relatively weak 2175 Å bumps observed in the Large Magellanic Cloud LMC2 supershell rather than the strong ones observed in the Milky Way. This sample has greatly increased the total number of 2175 Å extinction bumps measured on SDSS quasar spectra. Follow-up observations may rule out some of the possible false detections and reveal the physical and chemical natures of 2175 Å quasar absorbers.

Expanding Medicaid Access without Expanding Medicaid: Why Did Some Nonexpansion States Continue the Primary Care Fee Bump?

PubMed

Wilk, Adam S; Evans, Leigh C; Jones, David K

2018-02-01

Six states that have rejected the Patient Protection and Affordable Care Act's (ACA) Medicaid expansion nonetheless extended the primary care "fee bump," by which the federal government increased Medicaid fees for primary care services up to 100 percent of Medicare fees during 2013-14. We conducted semistructured interviews with leaders in five of these states, as well as in three comparison states, to examine why they would continue a provision of the ACA that moderately expands access at significant state expense while rejecting the expansion and its large federal match, focusing on relevant economic, political, and procedural factors. We found that fee bump extension proposals were more successful where they were dissociated from major national policy debates, actionable with the input of relatively few stakeholder entities, and well aligned with preexisting policy-making structures and decision trends. Republican proposals to cap or reduce federal funding for Medicaid, if enacted, would compel states to contain program costs. In this context, states' established decision-making processes for updating Medicaid fee schedules, which we elucidate in this study, may shape the future of the Medicaid program. Copyright © 2018 by Duke University Press 2018.

Flexible Chip Scale Package and Interconnect for Implantable MEMS Movable Microelectrodes for the Brain.

PubMed

Jackson, Nathan; Muthuswamy, Jit

2009-04-01

We report here a novel approach called MEMS microflex interconnect (MMFI) technology for packaging a new generation of Bio-MEMS devices that involve movable microelectrodes implanted in brain tissue. MMFI addresses the need for (i) operating space for movable parts and (ii) flexible interconnects for mechanical isolation. We fabricated a thin polyimide substrate with embedded bond-pads, vias, and conducting traces for the interconnect with a backside dry etch, so that the flexible substrate can act as a thin-film cap for the MEMS package. A double gold stud bump rivet bonding mechanism was used to form electrical connections to the chip and also to provide a spacing of approximately 15-20 µm for the movable parts. The MMFI approach achieved a chip scale package (CSP) that is lightweight, biocompatible, having flexible interconnects, without an underfill. Reliability tests demonstrated minimal increases of 0.35 mΩ, 0.23 mΩ and 0.15 mΩ in mean contact resistances under high humidity, thermal cycling, and thermal shock conditions respectively. High temperature tests resulted in an increase in resistance of > 90 mΩ when aluminum bond pads were used, but an increase of ~ 4.2 mΩ with gold bond pads. The mean-time-to-failure (MTTF) was estimated to be at least one year under physiological conditions. We conclude that MMFI technology is a feasible and reliable approach for packaging and interconnecting Bio-MEMS devices.

Processing and characterization of device solder interconnection and module attachment for power electronics modules

NASA Astrophysics Data System (ADS)

Haque, Shatil

This research is focused on the processing of an innovative three-dimensional packaging architecture for power electronics building blocks with soldered device interconnections and subsequent characterization of the module's critical interfaces. A low-cost approach termed metal posts interconnected parallel plate structure (MPIPPS) was developed for packaging high-performance modules of power electronics building blocks (PEBB). The new concept implemented direct bonding of copper posts, not wire bonding of fine aluminum wires, to interconnect power devices as well as joining the different circuit planes together. We have demonstrated the feasibility of this packaging approach by constructing PEBB modules (consisting of Insulated Gate Bipolar Transistors (IGBTs), diodes, and a few gate driver elements and passive components). In the 1st phase of module fabrication with IGBTs with Si3N 4 passivation, we had successfully fabricated packaged devices and modules using the MPIPPS technique. These modules were tested electrically and thermally, and they operated at pulse-switch and high power stages up to 6kW. However, in the 2nd phase of module fabrication with polyimide passivated devices, we experienced significant yield problems due to metallization difficulties of these devices. The under-bump metallurgy scheme for the development of a solderable interface involved sputtering of Ti-Ni-Cu and Cr-Cu, and an electroless deposition of Zn-Ni-Au metallization. The metallization process produced excellent yield in the case of Si3N4 passivated devices. However, under the same metallization schemes, devices with a polyimide passivation exhibited inconsistent electrical contact resistance. We found that organic contaminants such as hydrocarbons remain in the form of thin monolayers on the surface, even in the case of as-received devices from the manufacturer. Moreover, in the case of polyimide passivated devices, plasma cleaning introduced a few carbon constituents on the surface, which was not observed in the case of Si3N4 passivated devices. X-Ray Photoelectron Spectroscopy (XPS) Spectra showed evidence of possible carbon contaminants, such as carbide (˜282.9eV) and graphite (˜284.3eV) on the surface at binding energies below the binding energy of the hydrocarbon peak (C 1s at 285eV). Whereas above the hydrocarbon peak energy level, carbon-nitrogen compounds, single bond carbon compounds (˜285.9eV) and double bond carbon compounds (˜288.5eV) were evident. The majority of the carbon composition on the pad surface was associated with hydrocarbons, which were hydrophobic in nature, thus making the device contact pad less wettable. (Abstract shortened by UMI.)

THE PROPERTIES OF THE 2175 A EXTINCTION FEATURE DISCOVERED IN GRB AFTERGLOWS

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

Zafar, Tayyaba; Watson, Darach; Eliasdottir, Ardis

The unequivocal, spectroscopic detection of the 2175 A bump in extinction curves outside the Local Group is rare. To date, the properties of the bump have been examined in only two gamma-ray burst (GRB) afterglows (GRB 070802 and GRB 080607). In this work, we analyze in detail the detections of the 2175 Angstrom-Sign extinction bump in the optical spectra of two further GRB afterglows: GRB 080605 and 080805. We gather all available optical/near-infrared photometric, spectroscopic, and X-ray data to construct multi-epoch spectral energy distributions (SEDs) for both GRB afterglows. We fit the SEDs with the Fitzpatrick and Massa model withmore » a single or broken power law. We also fit a sample of 38 GRB afterglows, known to prefer a Small Magellanic Cloud (SMC)-type extinction curve, with the same model. We find that the SEDs of GRB 080605 and GRB 080805 at two epochs are fit well with a single power law with a derived extinction of A{sub V} = 0.52{sup +0.13}{sub -0.16} and 0.50{sup +0.13}{sub -0.10}, and 2.1{sup +0.7}{sub -0.6} and 1.5 {+-} 0.2, respectively. While the slope of the extinction curve of GRB 080805 is not well constrained, the extinction curve of GRB 080605 has an unusual very steep far-UV rise together with the 2175 A bump. Such an extinction curve has previously been found in only a small handful of sightlines in the Milky Way. One possible explanation of such an extinction curve may be dust arising from two different regions with two separate grain populations, however we cannot distinguish the origin of the curve. We finally compare the four 2175 A bump sightlines to the larger GRB afterglow sample and to Local Group sightlines. We find that while the width and central positions of the bumps are consistent with what is observed in the Local Group, the relative strength of the detected bump (A{sub bump}) for GRB afterglows is weaker for a given A{sub V} than for almost any Local Group sightline. Such dilution of the bump strength may offer tentative support to a dual dust-population scenario.« less

Empirical relationships between gas abundances and UV selective extinction

NASA Technical Reports Server (NTRS)

Joseph, Charles L.

1990-01-01

Several studies of gas-phase abundances in lines of sight through the outer edges of dense clouds are summarized. These lines of sight have 0.4 less than E(B-V) less than 1.1 and have inferred spatial densities of a few hundred cm(-3). The primary thrust of these studies has been to compare gaseous abundances in interstellar clouds that have various types of peculiar selective extinction. To date, the most notable result has been an empirical relationship between the CN/Fe I abundance ratio and the depth of the 2200 A extinction bump. It is not clear at the present time, however, whether these two parameters are linearly correlated or the data are organized into two discrete ensembles. Based on 19 samples and assuming the clouds form discrete ensembles, lines of sight that have a CN/Fe I abundance ratio greater than 0.3 (dex) appear to have a shallow 2.57 plus or minus 0.55 bump compared to 3.60 plus or minus 0.36 for other dense clouds and compared to the 3.6 Seaton (1979) average. The difference in the strength of the extinction bump between these two ensembles is 1.03 plus or minus 0.23. Although a high-resolution IUE survey of dense clouds is far from complete, the few lines of sight with shallow extinction bumps all show preferential depletion of certain elements, while those lines of sight with normal 2200 A bumps do not. Ca II, Cr II, and Mn II appear to exhibit the strongest preferential depletion compared to S II, P II, and Mg II. Fe II and Si II depletions also appear to be enhanced somewhat in the shallow-bump lines of sight. It should be noted that Copernicus data suggest all elements, including the so-called nondepletors, deplete in diffuse clouds (Snow and Jenkins 1980, Joseph 1988). Those lines of sight through dense clouds that have normal 2200 A extinction bumps appear to be extensions of the depletions found in the diffuse interstellar medium. That is, the overall level of depletion is enhanced, but the element-to-element abundances are similar to those in diffuse clouds. In a separate study, the abundances of neutral atoms were studied in a dense cloud having a shallow 2200 A bump and in one with a normal strength bump.

Aeroelasticity of morphing wings using neural networks

NASA Astrophysics Data System (ADS)

Natarajan, Anand

In this dissertation, neural networks are designed to effectively model static non-linear aeroelastic problems in adaptive structures and linear dynamic aeroelastic systems with time varying stiffness. The use of adaptive materials in aircraft wings allows for the change of the contour or the configuration of a wing (morphing) in flight. The use of smart materials, to accomplish these deformations, can imply that the stiffness of the wing with a morphing contour changes as the contour changes. For a rapidly oscillating body in a fluid field, continuously adapting structural parameters may render the wing to behave as a time variant system. Even the internal spars/ribs of the aircraft wing which define the wing stiffness can be made adaptive, that is, their stiffness can be made to vary with time. The immediate effect on the structural dynamics of the wing, is that, the wing motion is governed by a differential equation with time varying coefficients. The study of this concept of a time varying torsional stiffness, made possible by the use of active materials and adaptive spars, in the dynamic aeroelastic behavior of an adaptable airfoil is performed here. Another type of aeroelastic problem of an adaptive structure that is investigated here, is the shape control of an adaptive bump situated on the leading edge of an airfoil. Such a bump is useful in achieving flow separation control for lateral directional maneuverability of the aircraft. Since actuators are being used to create this bump on the wing surface, the energy required to do so needs to be minimized. The adverse pressure drag as a result of this bump needs to be controlled so that the loss in lift over the wing is made minimal. The design of such a "spoiler bump" on the surface of the airfoil is an optimization problem of maximizing pressure drag due to flow separation while minimizing the loss in lift and energy required to deform the bump. One neural network is trained using the CFD code FLUENT to represent the aerodynamic loading over the bump. A second neural network is trained for calculating the actuator loads, bump displacement and lift, drag forces over the airfoil using the finite element solver, ANSYS and the previously trained neural network. This non-linear aeroelastic model of the deforming bump on an airfoil surface using neural networks can serve as a fore-runner for other non-linear aeroelastic problems.

Planetesimal formation by an axisymmetric radial bump of the column density of the gas in a protoplanetary disk

NASA Astrophysics Data System (ADS)

Onishi, Isamu K.; Sekiya, Minoru

2017-04-01

We investigate the effect of a radial pressure bump in a protoplanetary disk on planetesimal formation. We performed the two-dimensional numerical simulation of the dynamical interaction of solid particles and gas with an initially defined pressure bump under the assumption of axisymmetry. The aim of this work is to elucidate the effects of the stellar vertical gravity that were omitted in a previous study. Our results are very different from the previous study, which omitted the vertical gravity. Because dust particles settle toward the midplane because of the vertical gravity to form a thin dust layer, the regions outside of the dust layer are scarcely affected by the back-reaction of the dust. Hence, the gas column density keeps its initial profile with a bump, and dust particles migrate toward the bump. In addition, the turbulence due to the Kelvin-Helmholtz instability caused by the difference of the azimuthal velocities between the inside and outside of the dust layer is suppressed where the radial pressure gradient is reduced by the pressure bump. The dust settling proceeds further where the turbulence is weak, and a number of dust clumps are formed. The dust density in some clumps exceeds the Roche density. Planetesimals are considered to be formed from these clumps owing to the self-gravity.[Figure not available: see fulltext.

Lichen Nitidus

MedlinePlus

... from pinpoint to pinhead size. Shape. They are flat topped and round. Color. Bumps are usually the ... usually characterized by patches of red or purple, flat-topped, itchy bumps on the skin or lacy ...

NASA Tech Briefs, June 2009

NASA Technical Reports Server (NTRS)

2009-01-01

Topics covered include: Device for Measuring Low Flow Speed in a Duct, Measuring Thermal Conductivity of a Small Insulation Sample, Alignment Jig for the Precise Measurement of THz Radiation, Autoignition Chamber for Remote Testing of Pyrotechnic Devices, Microwave Power Combiners for Signals of Arbitrary Amplitude, Synthetic Foveal Imaging Technology, Airborne Antenna System for Minimum-Cycle-Slip GPS Reception, Improved Starting Materials for Back-Illuminated Imagers, Multi-Modulator for Bandwidth-Efficient Communication, Some Improvements in Utilization of Flash Memory Devices, GPS/MEMS IMU/Microprocessor Board for Navigation, T/R Multi-Chip MMIC Modules for 150 GHz, Pneumatic Haptic Interfaces, Device Acquires and Retains Rock or Ice Samples, Cryogenic Feedthrough Test Rig, Improved Assembly for Gas Shielding During Welding or Brazing, Two-Step Plasma Process for Cleaning Indium Bonding Bumps, Tool for Crimping Flexible Circuit Leads, Yb14MnSb11 as a High-Efficiency Thermoelectric Material, Polyimide-Foam/Aerogel Composites for Thermal Insulation, Converting CSV Files to RKSML Files, Service Management Database for DSN Equipment, Chemochromic Hydrogen Leak Detectors, Compatibility of Segments of Thermoelectric Generators, Complementary Barrier Infrared Detector, JPL Greenland Moulin Exploration Probe, Ultra-Lightweight Self-Deployable Nanocomposite Structure for Habitat Applications, and Room-Temperature Ionic Liquids for Electrochemical Capacitors.

Interaction model between a liquid film and a spherical probe

NASA Astrophysics Data System (ADS)

Ledesma Alonso, Rene; Legendre, Dominique; Tordjeman, Philippe

2012-11-01

To find a liquid surface profile, when performing AFM measurements, probe interaction effects should be identified. Herein, the behavior of a liquid film free surface (thickness E, surface tension γ and density difference Δρ), disposed over a flat surface and in the presence of a spherical probe (radius R) is forecast. A bump-like surface shape is observed, due to the probe/film interaction (characterized by the Hamaker constant Hpl). In addition, the attraction between the film and the substrate (depicted by Hsl) opposes the axial and radial deformation ranges. Several parameters portray the equilibrium shape: Bond Bo = (ΔρgR2) / γ and modified Hamaker Ha = 4Hpl / (3 πγR2) numbers, Hamaker ratio A =Hls /Hpl , separation distance D / R and film thickness E / R . We focus on the effect of geometry, nevertheless special attention is given to the role of physical parameters. Employing an augmented Young-Laplace equation, the equilibrium profile is described by a strongly non-linear ODE. A critical distance, below which the irreversible wetting process of the spherical probe occurs, is predicted. Our results provide simple relationships between parameters, which determine the optimal scanning conditions over liquid films.

Recent developments in MrBUMP: better search-model preparation, graphical interaction with search models, and solution improvement and assessment.

PubMed

Keegan, Ronan M; McNicholas, Stuart J; Thomas, Jens M H; Simpkin, Adam J; Simkovic, Felix; Uski, Ville; Ballard, Charles C; Winn, Martyn D; Wilson, Keith S; Rigden, Daniel J

2018-03-01

Increasing sophistication in molecular-replacement (MR) software and the rapid expansion of the PDB in recent years have allowed the technique to become the dominant method for determining the phases of a target structure in macromolecular X-ray crystallography. In addition, improvements in bioinformatic techniques for finding suitable homologous structures for use as MR search models, combined with developments in refinement and model-building techniques, have pushed the applicability of MR to lower sequence identities and made weak MR solutions more amenable to refinement and improvement. MrBUMP is a CCP4 pipeline which automates all stages of the MR procedure. Its scope covers everything from the sourcing and preparation of suitable search models right through to rebuilding of the positioned search model. Recent improvements to the pipeline include the adoption of more sensitive bioinformatic tools for sourcing search models, enhanced model-preparation techniques including better ensembling of homologues, and the use of phase improvement and model building on the resulting solution. The pipeline has also been deployed as an online service through CCP4 online, which allows its users to exploit large bioinformatic databases and coarse-grained parallelism to speed up the determination of a possible solution. Finally, the molecular-graphics application CCP4mg has been combined with MrBUMP to provide an interactive visual aid to the user during the process of selecting and manipulating search models for use in MR. Here, these developments in MrBUMP are described with a case study to explore how some of the enhancements to the pipeline and to CCP4mg can help to solve a difficult case.

Recent developments in MrBUMP: better search-model preparation, graphical interaction with search models, and solution improvement and assessment

PubMed Central

Keegan, Ronan M.; McNicholas, Stuart J.; Thomas, Jens M. H.; Simpkin, Adam J.; Uski, Ville; Ballard, Charles C.

2018-01-01

Increasing sophistication in molecular-replacement (MR) software and the rapid expansion of the PDB in recent years have allowed the technique to become the dominant method for determining the phases of a target structure in macromolecular X-ray crystallography. In addition, improvements in bioinformatic techniques for finding suitable homologous structures for use as MR search models, combined with developments in refinement and model-building techniques, have pushed the applicability of MR to lower sequence identities and made weak MR solutions more amenable to refinement and improvement. MrBUMP is a CCP4 pipeline which automates all stages of the MR procedure. Its scope covers everything from the sourcing and preparation of suitable search models right through to rebuilding of the positioned search model. Recent improvements to the pipeline include the adoption of more sensitive bioinformatic tools for sourcing search models, enhanced model-preparation techniques including better ensembling of homologues, and the use of phase improvement and model building on the resulting solution. The pipeline has also been deployed as an online service through CCP4 online, which allows its users to exploit large bioinformatic databases and coarse-grained parallelism to speed up the determination of a possible solution. Finally, the molecular-graphics application CCP4mg has been combined with MrBUMP to provide an interactive visual aid to the user during the process of selecting and manipulating search models for use in MR. Here, these developments in MrBUMP are described with a case study to explore how some of the enhancements to the pipeline and to CCP4mg can help to solve a difficult case. PMID:29533225

MEMS Microshutter Array System for James Webb Space Telescope

NASA Technical Reports Server (NTRS)

Li, Mary J.; Adachi, Tomoko; Allen, Christine; Babu, Sachi; Bajikar, Sateesh; Beamesderfer, Michael; Bradley, Ruth; Denis, Kevin; Costen, Nick; Ewin, Audrey;

Modeling Charge Collection in Detector Arrays

NASA Technical Reports Server (NTRS)

Hardage, Donna (Technical Monitor); Pickel, J. C.

2003-01-01

A detector array charge collection model has been developed for use as an engineering tool to aid in the design of optical sensor missions for operation in the space radiation environment. This model is an enhancement of the prototype array charge collection model that was developed for the Next Generation Space Telescope (NGST) program. The primary enhancements were accounting for drift-assisted diffusion by Monte Carlo modeling techniques and implementing the modeling approaches in a windows-based code. The modeling is concerned with integrated charge collection within discrete pixels in the focal plane array (FPA), with high fidelity spatial resolution. It is applicable to all detector geometries including monolithc charge coupled devices (CCDs), Active Pixel Sensors (APS) and hybrid FPA geometries based on a detector array bump-bonded to a readout integrated circuit (ROIC).

A CMOS Time-Resolved Fluorescence Lifetime Analysis Micro-System

PubMed Central

Rae, Bruce R.; Muir, Keith R.; Gong, Zheng; McKendry, Jonathan; Girkin, John M.; Gu, Erdan; Renshaw, David; Dawson, Martin D.; Henderson, Robert K.

2009-01-01

We describe a CMOS-based micro-system for time-resolved fluorescence lifetime analysis. It comprises a 16 × 4 array of single-photon avalanche diodes (SPADs) fabricated in 0.35 μm high-voltage CMOS technology with in-pixel time-gated photon counting circuitry and a second device incorporating an 8 × 8 AlInGaN blue micro-pixellated light-emitting diode (micro-LED) array bump-bonded to an equivalent array of LED drivers realized in a standard low-voltage 0.35 μm CMOS technology, capable of producing excitation pulses with a width of 777 ps (FWHM). This system replaces instrumentation based on lasers, photomultiplier tubes, bulk optics and discrete electronics with a PC-based micro-system. Demonstrator lifetime measurements of colloidal quantum dot and Rhodamine samples are presented. PMID:22291564

CdZnTe Image Detectors for Hard-X-Ray Telescopes

NASA Technical Reports Server (NTRS)

Chen, C. M. Hubert; Cook, Walter R.; Harrison, Fiona A.; Lin, Jiao Y. Y.; Mao, Peter H.; Schindler, Stephen M.

2005-01-01

Arrays of CdZnTe photodetectors and associated electronic circuitry have been built and tested in a continuing effort to develop focal-plane image sensor systems for hard-x-ray telescopes. Each array contains 24 by 44 pixels at a pitch of 498 m. The detector designs are optimized to obtain low power demand with high spectral resolution in the photon- energy range of 5 to 100 keV. More precisely, each detector array is a hybrid of a CdZnTe photodetector array and an application-specific integrated circuit (ASIC) containing an array of amplifiers in the same pixel pattern as that of the detectors. The array is fabricated on a single crystal of CdZnTe having dimensions of 23.6 by 12.9 by 2 mm. The detector-array cathode is a monolithic platinum contact. On the anode plane, the contact metal is patterned into the aforementioned pixel array, surrounded by a guard ring that is 1 mm wide on three sides and is 0.1 mm wide on the fourth side so that two such detector arrays can be placed side-by-side to form a roughly square sensor area with minimal dead area between them. Figure 1 shows two anode patterns. One pattern features larger pixel anode contacts, with a 30-m gap between them. The other pattern features smaller pixel anode contacts plus a contact for a shaping electrode in the form of a grid that separates all the pixels. In operation, the grid is held at a potential intermediate between the cathode and anode potentials to steer electric charges toward the anode in order to reduce the loss of charges in the inter-anode gaps. The CdZnTe photodetector array is mechanically and electrically connected to the ASIC (see Figure 2), either by use of indium bump bonds or by use of conductive epoxy bumps on the CdZnTe array joined to gold bumps on the ASIC. Hence, the output of each pixel detector is fed to its own amplifier chain.

Soldering-induced Cu diffusion and intermetallic compound formation between Ni/Cu under bump metallization and SnPb flip-chip solder bumps

NASA Astrophysics Data System (ADS)

Huang, Chien-Sheng; Jang, Guh-Yaw; Duh, Jenq-Gong

2004-04-01

Nickel-based under bump metallization (UBM) has been widely used as a diffusion barrier to prevent the rapid reaction between the Cu conductor and Sn-based solders. In this study, joints with and without solder after heat treatments were employed to evaluate the diffusion behavior of Cu in the 63Sn-37Pb/Ni/Cu/Ti/Si3N4/Si multilayer structure. The atomic flux of Cu diffused through Ni was evaluated from the concentration profiles of Cu in solder joints. During reflow, the atomic flux of Cu was on the order of 1015-1016 atoms/cm2s. However, in the assembly without solder, no Cu was detected on the surface of Ni even after ten cycles of reflow. The diffusion behavior of Cu during heat treatments was studied, and the soldering-process-induced Cu diffusion through Ni metallization was characterized. In addition, the effect of Cu content in the solder near the solder/intermetallic compound (IMC) interface on interfacial reactions between the solder and the Ni/Cu UBM was also discussed. It is evident that the (Cu,Ni)6Sn5 IMC might form as the concentration of Cu in the Sn-Cu-Ni alloy exceeds 0.6 wt.%.

Indium-bump-free antimonide superlattice membrane detectors on silicon substrates

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

Zamiri, M., E-mail: mzamiri@chtm.unm.edu, E-mail: skrishna@chtm.unm.edu; Klein, B.; Schuler-Sandy, T.

2016-02-29

We present an approach to realize antimonide superlattices on silicon substrates without using conventional Indium-bump hybridization. In this approach, PIN superlattices are grown on top of a 60 nm Al{sub 0.6}Ga{sub 0.4}Sb sacrificial layer on a GaSb host substrate. Following the growth, the individual pixels are transferred using our epitaxial-lift off technique, which consists of a wet-etch to undercut the pixels followed by a dry-stamp process to transfer the pixels to a silicon substrate prepared with a gold layer. Structural and optical characterization of the transferred pixels was done using an optical microscope, scanning electron microscopy, and photoluminescence. The interface betweenmore » the transferred pixels and the new substrate was abrupt, and no significant degradation in the optical quality was observed. An Indium-bump-free membrane detector was then fabricated using this approach. Spectral response measurements provided a 100% cut-off wavelength of 4.3 μm at 77 K. The performance of the membrane detector was compared to a control detector on the as-grown substrate. The membrane detector was limited by surface leakage current. The proposed approach could pave the way for wafer-level integration of photonic detectors on silicon substrates, which could dramatically reduce the cost of these detectors.« less

Probing the driving region in hot subdwarf stars through nonadiabatic asteroseismology: the principle of the method

NASA Astrophysics Data System (ADS)

Charpinet, S.; Fontaine, G.; Brassard, P.

2009-01-01

Context: The κ-mechanism that drives pulsations in hot subdwarf stars is closely linked to the action of diffusive processes, including radiative levitation, which modulate the local contents of heavy elements in the stellar envelope. Iron, in particular, is important for its dominant contribution to the Z-bump feature in the envelope opacity, although other iron-peak elements, such as nickel for instance, may also play a significant role. Aims: Our main goal is to evaluate the potential of nonadiabatic asteroseismology for studying diffusive phenomena in these stars. In this exploratory work, we consider iron as a test case to establish the principle of the method. Methods: From model experiments, we explore the behavior of the pulsation engine under assumed local iron enrichments in the Z-bump layers, and we show how this may be related, through the period range of unstable modes, to some observed properties, i.e., the range of periods effectively detected, characterizing hot pulsating subdwarf stars. This connects nonadiabatic physics with observables. Results: We demonstrate that the strength of the pulsation engine is predominently controled by the amount of heavy metals (iron in our experiments) present at the Z-bump location, the chemical composition in other parts of the star being irrelevant to the process. We also show that this property can be used to probe directly the amount of metals present in this particular region, irrespective of the physical process involved to produce such abundances. In particular, we show that limits on the abundances needed for the onset of pulsations can be estimated. These can even be derived for individual stars based on their observed pulsation period range, as illustrated with two well-studied pulsating sdB stars: PG 1325+101 and Feige 48. Conclusions: We conclude by emphasizing the strong potential of nonadiabatic asteroseismology for hot subdwarf stars, which may hold the key for better understanding diffusive and competing mixing processes in stellar envelopes.

Iterative current mode per pixel ADC for 3D SoftChip implementation in CMOS

NASA Astrophysics Data System (ADS)

Lachowicz, Stefan W.; Rassau, Alexander; Lee, Seung-Minh; Eshraghian, Kamran; Lee, Mike M.

2003-04-01

Mobile multimedia communication has rapidly become a significant area of research and development constantly challenging boundaries on a variety of technological fronts. The processing requirements for the capture, conversion, compression, decompression, enhancement, display, etc. of increasingly higher quality multimedia content places heavy demands even on current ULSI (ultra large scale integration) systems, particularly for mobile applications where area and power are primary considerations. The ADC presented in this paper is designed for a vertically integrated (3D) system comprising two distinct layers bonded together using Indium bump technology. The top layer is a CMOS imaging array containing analogue-to-digital converters, and a buffer memory. The bottom layer takes the form of a configurable array processor (CAP), a highly parallel array of soft programmable processors capable of carrying out complex processing tasks directly on data stored in the top plane. This paper presents a ADC scheme for the image capture plane. The analogue photocurrent or sampled voltage is transferred to the ADC via a column or a column/row bus. In the proposed system, an array of analogue-to-digital converters is distributed, so that a one-bit cell is associated with one sensor. The analogue-to-digital converters are algorithmic current-mode converters. Eight such cells are cascaded to form an 8-bit converter. Additionally, each photo-sensor is equipped with a current memory cell, and multiple conversions are performed with scaled values of the photocurrent for colour processing.

Electrical characteristics for Sn-Ag-Cu solder bump with Ti/Ni/Cu under-bump metallization after temperature cycling tests

NASA Astrophysics Data System (ADS)

Shih, T. I.; Lin, Y. C.; Duh, J. G.; Hsu, Tom

2006-10-01

Lead-free solder bumps have been widely used in current flip-chip technology (FCT) due to environmental issues. Solder joints after temperature cycling tests were employed to investigate the interfacial reaction between the Ti/Ni/Cu under-bump metallization and Sn-Ag-Cu solders. The interfacial morphology and quantitative analysis of the intermetallic compounds (IMCs) were obtained by electron probe microanalysis (EPMA) and field emission electron probe microanalysis (FE-EPMA). Various types of IMCs such as (Cu1-x,Agx)6Sn5, (Cu1-y,Agy)3Sn, and (Ag1-z,Cuz)3Sn were observed. In addition to conventional I-V measurements by a special sample preparation technique, a scanning electron microscope (SEM) internal probing system was introduced to evaluate the electrical characteristics in the IMCs after various test conditions. The electrical data would be correlated to microstructural evolution due to the interfacial reaction between the solder and under-bump metallurgy (UBM). This study demonstrated the successful employment of an internal nanoprobing approach, which would help further understanding of the electrical behavior within an IMC layer in the solder/UBM assembly.

Trapping saturation of the bump-on-tail instability and electrostatic harmonic excitation in earth's foreshock

NASA Technical Reports Server (NTRS)

Klimas, Alexander J.

1990-01-01

The Vlasov simulation is used to examine the trapping saturation of the bump-on-tail instability both with and without mode-mode coupling and subsequent harmonic excitation. It is found that adding the pumped harmonic modes leads to a significant difference in the behavior of the phase-space distribution function near the unstable bump at the saturation time of the instability. The pumped modes permit rapid plateau formation on the space-averaged velocity distribution, in effect preventing the onset of the quasi-linear velocity-diffusion saturation mechanism.

Effect of suspension systems on the physiological and psychological responses to sub-maximal biking on simulated smoothand bumpy tracks.

PubMed

Titlestad, John; Fairlie-Clarke, Tony; Whittaker, Arthur; Davie, Mark; Watt, Ian; Grant, Stanley

2006-02-01

The aim of this study was to compare the physiological and psychological responses of cyclists riding on a hard tail bicycle and on a full suspension bicycle. Twenty males participated in two series of tests. A test rig held the front axle of the bicycle steady while the rear wheel rotated against a heavy roller with bumps (or no bumps) on its surface. In the first series of tests, eight participants (age 19-27 years, body mass 65-82 kg) were tested on both the full suspension and hard tail bicycles with and without bumps fitted to the roller. The second series of test repeated the bump tests with a further six participants (age 22-31 years, body mass 74-94 kg) and also involved an investigation of familiarization effects with the final six participants (age 21-30 years, body mass 64-80 kg). Heart rate, oxygen consumption (VO(2)), rating of perceived exertion (RPE) and comfort were recorded during 10 min sub-maximal tests. Combined data for the bumps tests show that the full suspension bicycle was significantly different (P < 0.001) from the hard tail bicycle on all four measures. Oxygen consumption, heart rate and RPE were lower on average by 8.7 (s = 3.6) ml . kg(-1) . min(-1), 32.1 (s = 12.1) beats . min(-1) and 2.6 (s = 2.0) units, respectively. Comfort scores were higher (better) on average by 1.9 (s = 0.8) units. For the no bumps tests, the only statistically significant difference (P = 0.008) was in VO(2), which was lower for the hard tail bicycle by 2.2 (s = 1.7) ml . kg(-1) . min(-1). The results indicate that the full suspension bicycle provides a physiological and psychological advantage over the hard tail bicycle during simulated sub-maximal exercise on bumps.

Detonative propagation and accelerative expansion of the Crab Nebula shock front.

PubMed

Gao, Yang; Law, Chung K

2011-10-21

The accelerative expansion of the Crab Nebula's outer envelope is a mystery in dynamics, as a conventional expanding blast wave decelerates when bumping into the surrounding interstellar medium. Here we show that the strong relativistic pulsar wind bumping into its surrounding nebula induces energy-generating processes and initiates a detonation wave that propagates outward to form the current outer edge, namely, the shock front, of the nebula. The resulting detonation wave, with a reactive downstream, then provides the needed power to maintain propagation of the shock front. Furthermore, relaxation of the curvature-induced reduction of the propagation velocity from the initial state of formation to the asymptotic, planar state of Chapman-Jouguet propagation explains the observed accelerative expansion. Potential richness in incorporating reactive fronts in the description of various astronomical phenomena is expected. © 2011 American Physical Society

The effects of wedge roughness on Mach formation

NASA Astrophysics Data System (ADS)

Needham, C. E.; Happ, H. J.; Dawson, D. F.

A modified HULL hydrodynamic model was used to simulate shock reflection on wedges fitted with bumps representing varying degrees of roughness. The protuberances ranged from 0.02-0.2 cm in size. The study was directed at the feasibility of and techniques for defining parametric fits for surface roughness in the HULL code. Of interest was the self-similarity of the flows, so increasingly larger protuberances would simply enhance the resolution of the calculations. The code was designed for compressible, inviscid, nonconducting fluid flows. An equation of state provides closure and a finite difference algorithm is applied to solve governing equations for conservation of mass, momentum and energy. Self-similarity failed as the surface bumps grew larger and protruded further into the flowfield. It is noted that bumps spaced further apart produced greater interference for the passage of the Mach stem than did bumps placed closer together.

Effect of current crowding on whisker growth at the anode in flip chip solder joints

NASA Astrophysics Data System (ADS)

Ouyang, Fan-Yi; Chen, Kai; Tu, K. N.; Lai, Yi-Shao

2007-12-01

Owing to the line-to-bump configuration in flip chip solder joints, current crowding occurs when electrons enter into or exit from the solder bump. At the cathode contact, where electrons enter into the bump, current crowding induced pancake-type void formation has now been observed widely. At the anode contact, where electrons exit from the bump, we report here that whisker is formed. Results of both eutectic SnPb and SnAgCu solder joints are presented and compared. The cross-sectioned surface in SnPb showed dimple and bulge after electromigration, while that of SnAgCu remained flat. The difference is due to a larger back stress in the SnAgCu, consequently, electromigration in SnAgCu is slower than that in SnPb. Nanoindentation markers were used to measure the combined atomic fluxes of back stress and electromigration.

Studies of beam injection with a compensated bump and uncompensated bump in a synchrotron

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

Akbar Fakhri, Ali; Prajapati, S. K.; Ghodke, A. D.

2013-08-15

Synchrotron radiation sources Indus-1 and Indus-2 have a synchrotron as the common injector. A three kicker compensated bump injection scheme was employed for beam injection into this synchrotron. The stored beam current in the synchrotron is higher, when all the three kickers are operated at the same current than when kickers are operated at currents required to generate compensated bump. Beam dynamics studies have been done to understand why this happens. Theoretical studies indicate that higher stored current in the later case is attributed to smaller residual oscillations of injected beam. These studies also reveal that if the angle ofmore » the injected beam during beam injection is kept varying, the performance could be further improved. This is experimentally confirmed by injecting the beam on rising part of the injection septum magnet current pulse.« less

Recommendations for design, construction, and maintenance of bridge approach slabs.

DOT National Transportation Integrated Search

2012-09-01

Settlement and heave related movements of bridge approach slabs relative to bridge decks create a bump in : the roadway. Several problems arise from these bumps, which include poor riding conditions, potential : vehicle damage, loss of vehicle contro...

Microelectromechanical systems-based visible-near infrared Fabry-Perot tunable filters using quartz substrate

NASA Astrophysics Data System (ADS)

Gupta, Neelam; Tan, Songsheng; Zander, Dennis R.

2012-07-01

There is a need to develop miniature optical tunable filters for small hyperspectral imagers. We plan to develop a number of miniature Fabry-Perot tunable filters (FPTFs) using microelectromechanical systems (MEMS) technology, each operating over a different wavelength region, to cover spectral regions from the visible to the longwave infrared (IR). Use of a MEMS-based FPTF as a dispersive element will reduce the size, weight, and power requirements of hyperspectral imagers and make them less expensive. A key requirement for such a filter is a large optical aperture. Recently, we succeeded in fabricating FPTFs with a 6 mm optical aperture operating in the visible to near IR spectral region (400 to 800 nm) using commercially available thin quartz wafers as the substrate. The FPTF design contains one fixed silver (Ag) mirror and one electrostatically movable Ag mirror, each grown on a quartz substrate with a low total thickness variation. Gold (Au) bumps are used to control the initial air gap distance between the two mirrors, and Au-Au bonding is used to bond the device. We describe material selection, device design, modeling, fabrication, interferometric, and spectral characterizations.

Solid-state image sensor with focal-plane digital photon-counting pixel array

NASA Technical Reports Server (NTRS)

Fossum, Eric R. (Inventor); Pain, Bedabrata (Inventor)

1995-01-01

A photosensitive layer such as a-Si for a UV/visible wavelength band is provided for low light level imaging with at least a separate CMOS amplifier directly connected to each PIN photodetector diode to provide a focal-plane array of NxN pixels, and preferably a separate photon-counting CMOS circuit directly connected to each CMOS amplifier, although one row of counters may be time shared for reading out the photon flux rate of each diode in the array, together with a buffer memory for storing all rows of the NxN image frame before transfer to suitable storage. All CMOS circuitry is preferably fabricated in the same silicon layer as the PIN photodetector diode for a monolithic structure, but when the wavelength band of interest requires photosensitive material different from silicon, the focal-plane array may be fabricated separately on a different semiconductor layer bump-bonded or otherwise bonded for a virtually monolithic structure with one free terminal of each diode directly connected to the input terminal of its CMOS amplifier and digital counter for integration of the photon flux rate at each photodetector of the array.

Recommendations for design, construction, and maintenance of bridge approach slabs : synthesis report.

DOT National Transportation Integrated Search

2009-04-01

Bridge approaches provide smooth and safe transition of vehicles from highway pavements to bridge : structures. However, settlement of the bridge approach slab relative to bridge decks usually creates a : bump in the roadway. The bump causes inconven...

On reducing bumps at pavement-bridge interface.

DOT National Transportation Integrated Search

2010-12-21

This report contains the causes and long-term solutions to the bumps at bridge/approach slab and/or approach slab/pavement interface. A research was conducted on both structural and geotechnical aspects of an approach slab. : A 3-D finite element ana...

Experiments and theory on parametric instabilities excited in HF heating experiments at HAARP

NASA Astrophysics Data System (ADS)

Kuo, Spencer; Snyder, Arnold; Lee, M. C.

2014-06-01

Parametric instabilities excited by O-mode HF heater and the induced ionospheric modification were explored via HAARP digisonde operated in a fast mode. The impact of excited Langmuir waves and upper hybrid waves on the ionosphere are manifested by bumps in the virtual spread, which expand the ionogram echoes upward as much as 140 km and the downward range spread of the sounding echoes, which exceeds 50 km over a significant frequency range. The theory of parametric instabilities is presented. The theory identifies the ionogram bump located between the 3.2 MHz heater frequency and the upper hybrid resonance frequency and the bump below the upper hybrid resonance frequency to be associated with the Langmuir and upper hybrid instabilities, respectively. The Langmuir bump is located close to the upper hybrid resonance frequency, rather than to the heater frequency, consistent with the theory. Each bump in the virtual height spread of the ionogram is similar to the cusp occurring in daytime ionograms at the E-F2 layer transition, indicating that there is a small ledge in the density profile similar to E-F2 layer transitions. The experimental results also show that the strong impact of the upper hybrid instability on the ionosphere can suppress the Langmuir instability.

Experiments and theory on parametric instabilities excited in HF heating experiments at HAARP

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

Kuo, Spencer; Snyder, Arnold; Lee, M. C.

2014-06-15

Parametric instabilities excited by O-mode HF heater and the induced ionospheric modification were explored via HAARP digisonde operated in a fast mode. The impact of excited Langmuir waves and upper hybrid waves on the ionosphere are manifested by bumps in the virtual spread, which expand the ionogram echoes upward as much as 140 km and the downward range spread of the sounding echoes, which exceeds 50 km over a significant frequency range. The theory of parametric instabilities is presented. The theory identifies the ionogram bump located between the 3.2 MHz heater frequency and the upper hybrid resonance frequency and the bump below themore » upper hybrid resonance frequency to be associated with the Langmuir and upper hybrid instabilities, respectively. The Langmuir bump is located close to the upper hybrid resonance frequency, rather than to the heater frequency, consistent with the theory. Each bump in the virtual height spread of the ionogram is similar to the cusp occurring in daytime ionograms at the E-F2 layer transition, indicating that there is a small ledge in the density profile similar to E-F2 layer transitions. The experimental results also show that the strong impact of the upper hybrid instability on the ionosphere can suppress the Langmuir instability.« less

Applying robust design to study the effects of stratigraphic characteristics on brittle failure and bump potential in a coal mine

PubMed Central

Kim, Bo-Hyun; Larson, Mark K.; Lawson, Heather E.

2018-01-01

Bumps and other types of dynamic failure have been a persistent, worldwide problem in the underground coal mining industry, spanning decades. For example, in just five states in the U.S. from 1983 to 2014, there were 388 reportable bumps. Despite significant advances in mine design tools and mining practices, these events continue to occur. Many conditions have been associated with bump potential, such as the presence of stiff units in the local geology. The effect of a stiff sandstone unit on the potential for coal bumps depends on the location of the stiff unit in the stratigraphic column, the relative stiffness and strength of other structural members, and stress concentrations caused by mining. This study describes the results of a robust design to consider the impact of different lithologic risk factors impacting dynamic failure risk. Because the inherent variability of stratigraphic characteristics in sedimentary formations, such as thickness, engineering material properties, and location, is significant and the number of influential parameters in determining a parametric study is large, it is impractical to consider every simulation case by varying each parameter individually. Therefore, to save time and honor the statistical distributions of the parameters, it is necessary to develop a robust design to collect sufficient sample data and develop a statistical analysis method to draw accurate conclusions from the collected data. In this study, orthogonal arrays, which were developed using the robust design, are used to define the combination of the (a) thickness of a stiff sandstone inserted on the top and bottom of a coal seam in a massive shale mine roof and floor, (b) location of the stiff sandstone inserted on the top and bottom of the coal seam, and (c) material properties of the stiff sandstone and contacts as interfaces using the 3-dimensional numerical model, FLAC3D. After completion of the numerical experiments, statistical and multivariate analysis are performed using the calculated results from the orthogonal arrays to analyze the effect of these variables. As a consequence, the impact of each of the parameters on the potential for bumps is quantitatively classified in terms of a normalized intensity of plastic dissipated energy. By multiple regression, the intensity of plastic dissipated energy and migration of the risk from the roof to the floor via the pillars is predicted based on the value of the variables. The results demonstrate and suggest a possible capability to predict the bump potential in a given rock mass adjacent to the underground excavations and pillars. Assessing the risk of bumps is important to preventing fatalities and injuries resulting from bumps. PMID:29416902

Speed Bumps: A Student-Friendly Guide to Qualitative Research.

ERIC Educational Resources Information Center

Weis, Lois; Fine, Michelle

This book is designed to help undergraduate and graduate students begin a discussion about the technicalities, politics, and ethics surrounding qualitative research, focusing on research in the interest of social justice. It offers a view of how two researchers have conceptualized their own research process and renders problematic many of the…

Weak bump quasars

NASA Technical Reports Server (NTRS)

Wilkes, B. J.; Mcdowell, J.

1994-01-01

Research into the optical, ultraviolet and infrared continuum emission from quasars and their host galaxies was carried out. The main results were the discovery of quasars with unusually weak infrared emission and the construction of a quantitative estimate of the dispersion in quasar continuum properties. One of the major uncertainties in the measurement of quasar continuum strength is the contribution to the continuum of the quasar host galaxy as a function of wavelength. Continuum templates were constructed for different types of host galaxy and individual estimates made of the decomposed quasar and host continua based on existing observations of the target quasars. The results are that host galaxy contamination is worse than previously suspected, and some apparent weak bump quasars are really normal quasars with strong host galaxies. However, the existence of true weak bump quasars such as PHL 909 was confirmed. The study of the link between the bump strength and other wavebands was continued by comparing with IRAS data. There is evidence that excess far infrared radiation is correlated with weaker ultraviolet bumps. This argues against an orientation effect and implies a probable link with the host galaxy environment, for instance the presence of a luminous starburst. However, the evidence still favors the idea that reddening is not important in those objects with ultraviolet weak bumps. The same work has led to the discovery of a class of infrared weak quasars. Pushing another part of the envelope of quasar continuum parameter space, the IR-weak quasars have implications for understanding the effects of reddening internal to the quasars, the reality of ultraviolet turnovers, and may allow further tests of the Phinney dust model for the IR continuum. They will also be important objects for studying the claimed IR to x-ray continuum correlation.

Functional Cooperation between the IP3 Receptor and Phospholipase C Secures the High Sensitivity to Light of Drosophila Photoreceptors In Vivo

PubMed Central

Kohn, Elkana; Katz, Ben; Yasin, Bushra; Peters, Maximilian; Rhodes, Elisheva; Zaguri, Rachel; Weiss, Shirley

2015-01-01

Drosophila phototransduction is a model system for the ubiquitous phosphoinositide signaling. In complete darkness, spontaneous unitary current events (dark bumps) are produced by spontaneous single Gqα activation, while single-photon responses (quantum bumps) arise from synchronous activation of several Gqα molecules. We have recently shown that most of the spontaneous single Gqα activations do not produce dark bumps, because of a critical phospholipase Cβ (PLCβ) activity level required for bump generation. Surpassing the threshold of channel activation depends on both PLCβ activity and cellular [Ca2+], which participates in light excitation via a still unclear mechanism. We show here that in IP3 receptor (IP3R)-deficient photoreceptors, both light-activated Ca2+ release from internal stores and light sensitivity were strongly attenuated. This was further verified by Ca2+ store depletion, linking Ca2+ release to light excitation. In IP3R-deficient photoreceptors, dark bumps were virtually absent and the quantum-bump rate was reduced, indicating that Ca2+ release from internal stores is necessary to reach the critical level of PLCβ catalytic activity and the cellular [Ca2+] required for excitation. Combination of IP3R knockdown with reduced PLCβ catalytic activity resulted in highly suppressed light responses that were partially rescued by cellular Ca2+ elevation, showing a functional cooperation between IP3R and PLCβ via released Ca2+. These findings suggest that in contrast to the current dogma that Ca2+ release via IP3R does not participate in light excitation, we show that released Ca2+ plays a critical role in light excitation. The positive feedback between PLCβ and IP3R found here may represent a common feature of the inositol-lipid signaling. PMID:25673847

Real-time system for measuring three-dimensional shape of solder bump array by focus using varifocal mirror

NASA Astrophysics Data System (ADS)

Ishii, Akira; Tai, Haruka; Mitsudo, Jun

2007-10-01

This paper describes a real-time system for measuring the three-dimensional shape of solder bumps arrayed on an LSI chip-size-package (CSP) board presented for inspection based on the shape-from-focus technique. It uses a copper-alloy mirror deformed by a piezoelectric actuator as a varifocal mirror enabling a simple, fast, precise focusing mechanism without moving parts to be built. A practical measuring speed of 1.69 s/package for a small CSP board (4 x 4 mm2) was achieved by incorporating an exclusive field programmable gate array processor to calculate focus measure and by constructing a domed array of LEDs as a high-intensity, uniform illumination system so that a fast (150 fps) and high-resolution (1024 x 1024 pixels/frame) CMOS image sensor could be used. Accurate measurements of bump height were also achieved with errors of 10 μm (2σ) meeting the requirements for testing the coplanarity of a bump array.

GIANT X-RAY BUMP IN GRB 121027A: EVIDENCE FOR FALL-BACK DISK ACCRETION

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

Wu Xuefeng; Hou Shujin; Lei Weihua, E-mail: xfwu@pmo.ac.cn, E-mail: leiwh@hust.edu.cn

2013-04-20

A particularly interesting discovery in observations of GRB 121027A is that of a giant X-ray bump detected by the Swift/X-Ray Telescope. The X-ray afterglow re-brightens sharply at {approx}10{sup 3} s after the trigger by more than two orders of magnitude in less than 200 s. This X-ray bump lasts for more than 10{sup 4} s. It is quite different from typical X-ray flares. In this Letter we propose a fall-back accretion model to interpret this X-ray bump within the context of the collapse of a massive star for a long-duration gamma-ray burst. The required fall-back radius of {approx}3.5 Multiplication-Sign 10{supmore » 10} cm and mass of {approx}0.9-2.6 M{sub Sun} imply that a significant part of the helium envelope should survive through the mass loss during the last stage of the massive progenitor of GRB 121027A.« less

Investigation of Intrinsic and External Factors Contributing to the Occurrence of Coal Bumps in the Mining Area of Western Beijing, China

NASA Astrophysics Data System (ADS)

Wang, Hongwei; Jiang, Yaodong; Xue, Sheng; Pang, Xufeng; Lin, Zhinan; Deng, Daixin

2017-04-01

An investigation has been made to relate the occurrence of coal bumps to specific geological and mining conditions to the mining area of western Beijing. This investigation demonstrates that the high frequency of coal bumps in this area is due to four localized conditions, namely intrinsic coal properties, the presence of overturned strata and thrust faults, high in situ stress and the extraction of coal from island mining faces. Laboratory tests of coal samples indicated that the coals have a short duration of dynamic fracture, high bursting energy and high elastic strain energy, indicating that the coal is intrinsically prone to the occurrence of coal bumps. This investigation has also revealed that there are overturned strata and well-developed large- and medium-scale thrust faults in this area, and the presence of these structures results in plastic flow, severe discontinuities, rapid changes in overburden thickness and dipping of the coal seams. Well-developed secondary fold structures are also present in the axes and limbs of the primary folds. The instability of thrust faults, in combination with large-scale intrusion of igneous rocks, is closely associated with sudden roof breaking and induces sharp variations in electromagnetic radiation (EMR) and micro-seismic signals, which could be used to help predict coal bumps. In situ stress tests in the mining area demonstrate that the maximum and minimum principal stresses are nearly horizontal and that the intermediate principal stress is approximately vertical. The in situ stress level in the area is higher than the average in the Beijing area, North China and mainland China. In addition to the presence of overturned strata and thrust faults and high in situ stress levels, another external factor contributing to the frequency of coal bumps is coal extraction from island mining faces in this area. Island mining faces experience intermittent mining-induced abutment stress when a fault exists at one side of the island mining face due to reactivation of the fault, and this stress redistribution increases the likelihood of coal bumps during coal extraction from island mining faces.

3D-FBK Pixel Sensors: Recent Beam Tests Results with Irradiated Devices

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

Micelli, A.; /INFN, Trieste /Udine U.; Helle, K.

2012-04-30

The Pixel Detector is the innermost part of the ATLAS experiment tracking device at the Large Hadron Collider, and plays a key role in the reconstruction of the primary vertices from the collisions and secondary vertices produced by short-lived particles. To cope with the high level of radiation produced during the collider operation, it is planned to add to the present three layers of silicon pixel sensors which constitute the Pixel Detector, an additional layer (Insertable B-Layer, or IBL) of sensors. 3D silicon sensors are one of the technologies which are under study for the IBL. 3D silicon technology ismore » an innovative combination of very-large-scale integration and Micro-Electro-Mechanical-Systems where electrodes are fabricated inside the silicon bulk instead of being implanted on the wafer surfaces. 3D sensors, with electrodes fully or partially penetrating the silicon substrate, are currently fabricated at different processing facilities in Europe and USA. This paper reports on the 2010 June beam test results for irradiated 3D devices produced at FBK (Trento, Italy). The performance of these devices, all bump-bonded with the ATLAS pixel FE-I3 read-out chip, is compared to that observed before irradiation in a previous beam test.« less

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

Philipp, Hugh T.; Tate, Mark W.; Purohit, Prafull

A wide-dynamic-range imaging X-ray detector designed for recording successive frames at rates up to 10 MHz is described. X-ray imaging with frame rates of up to 6.5 MHz have been experimentally verified. The pixel design allows for up to 8–12 frames to be stored internally at high speed before readout, which occurs at a 1 kHz frame rate. An additional mode of operation allows the integration capacitors to be re-addressed repeatedly before readout which can enhance the signal-to-noise ratio of cyclical processes. This detector, along with modern storage ring sources which provide short (10–100 ps) and intense X-ray pulses atmore » megahertz rates, opens new avenues for the study of rapid structural changes in materials. The detector consists of hybridized modules, each of which is comprised of a 500 µm-thick silicon X-ray sensor solder bump-bonded, pixel by pixel, to an application-specific integrated circuit. The format of each module is 128 × 128 pixels with a pixel pitch of 150 µm. In the prototype detector described here, the three-side buttable modules are tiled in a 3 × 2 array with a full format of 256 × 384 pixels. Lastly, we detail the characteristics, operation, testing and application of the detector.« less

PFM2: a 32 × 32 processor for X-ray diffraction imaging at FELs

NASA Astrophysics Data System (ADS)

Manghisoni, M.; Fabris, L.; Re, V.; Traversi, G.; Ratti, L.; Grassi, M.; Lodola, L.; Malcovati, P.; Vacchi, C.; Pancheri, L.; Benkechcache, M. E. A.; Dalla Betta, G.-F.; Xu, H.; Verzellesi, G.; Ronchin, S.; Boscardin, M.; Batignani, G.; Bettarini, S.; Casarosa, G.; Forti, F.; Giorgi, M.; Paladino, A.; Paoloni, E.; Rizzo, G.; Morsani, F.

2016-11-01

This work is concerned with the design of a readout chip for application to experiments at the next generation X-ray Free Electron Lasers (FEL). The ASIC, named PixFEL Matrix (PFM2), has been designed in a 65 nm CMOS technology and consists of 32 × 32 pixels. Each cell covers an area of 110 × 110 μm2 and includes a low-noise charge sensitive amplifier (CSA) with dynamic signal compression, a time-variant shaper used to process the preamplifier output signal, a 10-bit successive approximation register (SAR) analog-to-digital converter (ADC) and digital circuitry for channel control and data readout. Two different solutions for the readout channel, based on different versions of the time-variant filter, have been integrated in the chip. Both solutions can be operated in such a way to cope with the high frame rate (exceeding 1 MHz) foreseen for future X-ray FEL machines. The ASIC will be bump bonded to a slim/active edge pixel sensor to form the first demonstrator for the PixFEL X-ray imager. This work has been carried out in the frame of the PixFEL project funded by Istituto Nazionale di Fisica Nucleare (INFN), Italy.

Characterization of the Photon Counting CHASE Jr., Chip Built in a 40-nm CMOS Process With a Charge Sharing Correction Algorithm Using a Collimated X-Ray Beam

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

Krzyżanowska, A.; Deptuch, G. W.; Maj, P.

This paper presents the detailed characterization of a single photon counting chip, named CHASE Jr., built in a CMOS 40-nm process, operating with synchrotron radiation. The chip utilizes an on-chip implementation of the C8P1 algorithm. The algorithm eliminates the charge sharing related uncertainties, namely, the dependence of the number of registered photons on the discriminator’s threshold, set for monochromatic irradiation, and errors in the assignment of an event to a certain pixel. The article presents a short description of the algorithm as well as the architecture of the CHASE Jr., chip. The analog and digital functionalities, allowing for proper operationmore » of the C8P1 algorithm are described, namely, an offset correction for two discriminators independently, two-stage gain correction, and different operation modes of the digital blocks. The results of tests of the C8P1 operation are presented for the chip bump bonded to a silicon sensor and exposed to the 3.5- μm -wide pencil beam of 8-keV photons of synchrotron radiation. It was studied how sensitive the algorithm performance is to the chip settings, as well as the uniformity of parameters of the analog front-end blocks. Presented results prove that the C8P1 algorithm enables counting all photons hitting the detector in between readout channels and retrieving the actual photon energy.« less

Medipix2 as a tool for proton beam characterization

NASA Astrophysics Data System (ADS)

Bisogni, M. G.; Cirrone, G. A. P.; Cuttone, G.; Del Guerra, A.; Lojacono, P.; Piliero, M. A.; Romano, F.; Rosso, V.; Sipala, V.; Stefanini, A.

2009-08-01

Proton therapy is a technique used to deliver a highly accurate and effective dose for the treatment of a variety of tumor diseases. The possibility to have an instrument able to give online information could reduce the time necessary to characterize the proton beam. To this aim we propose a detection system for online proton beam characterization based on the Medipix2 chip. Medipix2 is a detection system based on a single event counter read-out chip, bump-bonded to silicon pixel detector. The read-out chip is a matrix of 256×256 cells, 55×55 μm 2 each. To demonstrate the capabilities of Medipix2 as a proton detector, we have used a 62 MeV flux proton beam at the CATANA beam line of the LNS-INFN laboratory. The measurements performed confirmed the good imaging performances of the Medipix2 system also for the characterization of proton beams.

Nonlinear detection of secondary isotopic chemical shifts in NMR through spin noise

PubMed Central

Pöschko, Maria Theresia; Rodin, Victor V.; Schlagnitweit, Judith; Müller, Norbert; Desvaux, Hervé

2017-01-01

The detection of minor species in the presence of large amounts of similar main components remains a key challenge in analytical chemistry, for instance, to obtain isotopic fingerprints. As an alternative to the classical NMR scheme based on coherent excitation and detection, here we introduce an approach based on spin-noise detection. Chemical shifts and transverse relaxation rates are determined using only the detection circuit. Thanks to a nonlinear effect in mixtures with small chemical shift dispersion, small signals on top of a larger one can be observed with increased sensitivity as bumps on a dip; the latter being the signature of the main magnetization. Experimental observations are underpinned by an analytical theory: the coupling between the magnetization and the coil provides an amplified detection capability of both small static magnetic field inhomogeneities and small NMR signals. This is illustrated by two-bond 12C/13C isotopic measurements. PMID:28067218

Multi-spectral imaging with infrared sensitive organic light emitting diode

PubMed Central

Kim, Do Young; Lai, Tzung-Han; Lee, Jae Woong; Manders, Jesse R.; So, Franky

2014-01-01

Commercially available near-infrared (IR) imagers are fabricated by integrating expensive epitaxial grown III-V compound semiconductor sensors with Si-based readout integrated circuits (ROIC) by indium bump bonding which significantly increases the fabrication costs of these image sensors. Furthermore, these typical III-V compound semiconductors are not sensitive to the visible region and thus cannot be used for multi-spectral (visible to near-IR) sensing. Here, a low cost infrared (IR) imaging camera is demonstrated with a commercially available digital single-lens reflex (DSLR) camera and an IR sensitive organic light emitting diode (IR-OLED). With an IR-OLED, IR images at a wavelength of 1.2 µm are directly converted to visible images which are then recorded in a Si-CMOS DSLR camera. This multi-spectral imaging system is capable of capturing images at wavelengths in the near-infrared as well as visible regions. PMID:25091589

X-ray metrology of an array of active edge pixel sensors for use at synchrotron light sources

NASA Astrophysics Data System (ADS)

Plackett, R.; Arndt, K.; Bortoletto, D.; Horswell, I.; Lockwood, G.; Shipsey, I.; Tartoni, N.; Williams, S.

2018-01-01

We report on the production and testing of an array of active edge silicon sensors as a prototype of a large array. Four Medipix3RX.1 chips were bump bonded to four single chip sized Advacam active edge n-on-n sensors. These detectors were then mounted into a 2 by 2 array and tested on B16 at Diamond Light Source with an x-ray beam spot of 2um. The results from these tests, compared with optical metrology demonstrate that this type of sensor is sensitive to the physical edge of the silicon, with only a modest loss of efficiency in the final two rows of pixels. We present the efficiency maps recorded with the microfocus beam and a sample powder diffraction measurement. These results give confidence that this sensor technology can be used effectively in larger arrays of detectors at synchrotron light sources.

Characterisation of the high dynamic range Large Pixel Detector (LPD) and its use at X-ray free electron laser sources

NASA Astrophysics Data System (ADS)

Veale, M. C.; Adkin, P.; Booker, P.; Coughlan, J.; French, M. J.; Hart, M.; Nicholls, T.; Schneider, A.; Seller, P.; Pape, I.; Sawhney, K.; Carini, G. A.; Hart, P. A.

2017-12-01

The STFC Rutherford Appleton Laboratory have delivered the Large Pixel Detector (LPD) for MHz frame rate imaging at the European XFEL. The detector system has an active area of 0.5 m × 0.5 m and consists of a million pixels on a 500 μm pitch. Sensors have been produced from 500 μm thick Hammamatsu silicon tiles that have been bump bonded to the readout ASIC using a silver epoxy and gold stud technique. Each pixel of the detector system is capable of measuring 105 12 keV photons per image readout at 4.5 MHz. In this paper results from the testing of these detectors at the Diamond Light Source and the Linac Coherent Light Source (LCLS) are presented. The performance of the detector in terms of linearity, spatial uniformity and the performance of the different ASIC gain stages is characterised.

Multi-spectral imaging with infrared sensitive organic light emitting diode

NASA Astrophysics Data System (ADS)

Kim, Do Young; Lai, Tzung-Han; Lee, Jae Woong; Manders, Jesse R.; So, Franky

2014-08-01

Commercially available near-infrared (IR) imagers are fabricated by integrating expensive epitaxial grown III-V compound semiconductor sensors with Si-based readout integrated circuits (ROIC) by indium bump bonding which significantly increases the fabrication costs of these image sensors. Furthermore, these typical III-V compound semiconductors are not sensitive to the visible region and thus cannot be used for multi-spectral (visible to near-IR) sensing. Here, a low cost infrared (IR) imaging camera is demonstrated with a commercially available digital single-lens reflex (DSLR) camera and an IR sensitive organic light emitting diode (IR-OLED). With an IR-OLED, IR images at a wavelength of 1.2 µm are directly converted to visible images which are then recorded in a Si-CMOS DSLR camera. This multi-spectral imaging system is capable of capturing images at wavelengths in the near-infrared as well as visible regions.

Properties of GaAs:Cr-based Timepix detectors

NASA Astrophysics Data System (ADS)

Smolyanskiy, P.; Bergmann, B.; Chelkov, G.; Kotov, S.; Kruchonak, U.; Kozhevnikov, D.; Mora Sierra, Y.; Stekl, I.; Zhemchugov, A.

2018-02-01

The hybrid pixel detector technology brought to the X-ray imaging a low noise level at a high spatial resolution, thanks to the single photon counting. However, silicon as the most widespread detector material is marginally sensitive to photons with energies above 30 keV. Therefore, the high-Z alternatives to silicon such as gallium arsenide and cadmium telluride are increasingly attracting attention of the community for the development of X-ray imaging systems. The results of our investigations of the Timepix detectors bump bonded to sensors made of gallium arsenide compensated by chromium (GaAs:Cr) are presented in this work. The following properties are most important from the practical point of view: the IV characteristics, the charge transport characteristics, photon detection efficiency, operational stability, homogeneity, temperature dependence, as well as energy and spatial resolution are considered. The applicability of these detectors for spectroscopic X-ray imaging is discussed.

Reading in Middle School: Bumps in the Literacy Crossroads

ERIC Educational Resources Information Center

Hall, Katrina Willard

2008-01-01

Certainly a major bump in the literacy road today is the apparent conflict between school literacies and the preferred literacy activities of students outside of school. After family conversation about a nephew who was getting poor grades in language arts, Hall shares her thinking on the dilemmas of what constitutes literacy, how literacies kids…

Location-Control of Large Si Grains by Dual-Beam Excimer-Laser and Thick Oxide Portion

NASA Astrophysics Data System (ADS)

Ishihara, Ryoichi; Burtsev, Artyom; Alkemade, Paul F. A.

2000-07-01

An array of large Si grains was placed at a predetermined position by dual excimer-laser irradiation of a multi-layer structure of silicon (Si), silicon dioxide (SiO2) with an array of bumps and metal on a glass substrate. We have investigated the effects of irradiating energy density and the topology of the structure on the grain size and crystallographic structure by scanning electron microscopy (SEM) and electron back-scattering pattern (EBSP) analysis. In the low-energy-density regime, numerous small grains and petal shaped grains formed on top of the SiO2 bumps. The number of small grains on the bumps decreased with increasing irradiating energy density. At sufficiently high energy densities, one single Si grain as large as 3.5 μm was positioned at the center of the bumps. Although most of the area of the large Si grain has a single crystallographic orientation, twins and low-angle grain boundaries are often formed at the periphery of the grain. There was no preferred crystallographic orientation in the center of the location-controlled Si grain. Numerical analysis of the temperature profile showed that a temperature drop occurs at the center of the bump, during and immediately after laser irradiation. The diameter of the location-controlled Si grain increased with total thickness of the intermediate SiO2 layer, and took the maximum value of 6.2 μm.

Thick resist for MEMS processing

NASA Astrophysics Data System (ADS)

Brown, Joe; Hamel, Clifford

2001-11-01

The need for technical innovation is always present in today's economy. Microfabrication methods have evolved in support of the demand for smaller and faster integrated circuits with price performance improvements always in the scope of the manufacturing design engineer. The dispersion of processing technology spans well beyond IC fabrication today with batch fabrication and wafer scale processing lending advantages to MEMES applications from biotechnology to consumer electronics from oil exploration to aerospace. Today the demand for innovative processing techniques that enable technology is apparent where only a few years ago appeared too costly or not reliable. In high volume applications where yield and cost improvements are measured in fractions of a percent it is imperative to have process technologies that produce consistent results. Only a few years ago thick resist coatings were limited to thickness less than 20 microns. Factors such as uniformity, edge bead and multiple coatings made high volume production impossible. New developments in photoresist formulation combined with advanced coating equipment techniques that closely controls process parameters have enable thick photoresist coatings of 70 microns with acceptable uniformity and edge bead in one pass. Packaging of microelectronic and micromechanical devices is often a significant cost factor and a reliability issue for high volume low cost production. Technologies such as flip- chip assembly provide a solution for cost and reliability improvements over wire bond techniques. The processing for such technology demands dimensional control and presents a significant cost savings if it were compatible with mainstream technologies. Thick photoresist layers, with good sidewall control would allow wafer-bumping technologies to penetrate the barriers to yield and production where costs for technology are the overriding issue. Single pass processing is paramount to the manufacturability of packaging technology. Uniformity and edge bead control defined the success of process implementation. Today advanced packaging solutions are created with thick photoresist coatings. The techniques and results will be presented.

Sensory feedback in a bump attractor model of path integration.

PubMed

Poll, Daniel B; Nguyen, Khanh; Kilpatrick, Zachary P

2016-04-01

Mammalian spatial navigation systems utilize several different sensory information channels. This information is converted into a neural code that represents the animal's current position in space by engaging place cell, grid cell, and head direction cell networks. In particular, sensory landmark (allothetic) cues can be utilized in concert with an animal's knowledge of its own velocity (idiothetic) cues to generate a more accurate representation of position than path integration provides on its own (Battaglia et al. The Journal of Neuroscience 24(19):4541-4550 (2004)). We develop a computational model that merges path integration with feedback from external sensory cues that provide a reliable representation of spatial position along an annular track. Starting with a continuous bump attractor model, we explore the impact of synaptic spatial asymmetry and heterogeneity, which disrupt the position code of the path integration process. We use asymptotic analysis to reduce the bump attractor model to a single scalar equation whose potential represents the impact of asymmetry and heterogeneity. Such imperfections cause errors to build up when the network performs path integration, but these errors can be corrected by an external control signal representing the effects of sensory cues. We demonstrate that there is an optimal strength and decay rate of the control signal when cues appear either periodically or randomly. A similar analysis is performed when errors in path integration arise from dynamic noise fluctuations. Again, there is an optimal strength and decay of discrete control that minimizes the path integration error.

The Influence of Road Bumps Characteristics on the Chaotic Vibration of a Nonlinear Full-Vehicle Model with Driver

NASA Astrophysics Data System (ADS)

Fakhraei, J.; Khanlo, H. M.; Ghayour, M.; Faramarzi, Kh.

In this paper, the chaotic behavior of a ground vehicle system with driver subjected to road disturbances is studied and the relationship between the nonlinear vibration of the vehicle and ride comfort is evaluated. The vehicle system is modeled as fully nonlinear with seven degrees of freedom and an additional degree of freedom for driver (8-DOF). The excitation force is the road irregularities that are assumed as road speed control bumps. The sinusoidal, consecutive half-sine and dented-rectangular waveforms are considered to simulate the road speed control bumps. The nonlinearities of the system are due to the nonlinear springs and dampers that are used in the suspension system and tires. The governing differential equations are extracted under Newton-Euler laws and solved via numerical methods. The chaotic behaviors were studied in more detail with special techniques such as bifurcation diagrams, phase plane portrait, Poincaré map and Lyapunov exponents. The ride comfort was evaluated as the RMS value of the vertical displacement of the vehicle body and driver. Firstly, the effect of amplitude (height) and frequency (vehicle’s speed) of these speed control bumps on chaotic vibrations of vehicle are studied. The obtained results show that various forms of vibrations, such as periodic, subharmonic and chaotic vibrations, can be detected in the system behavior with the change of the height and frequency of speed control bumps and present different types of strange attractors in the vehicle with and without driver. Then, the influence of nonlinear vibration on ride comfort and the relationship between chaotic vibrations of the vehicle and driving comfort are investigated. The results of analyzing the RMS diagrams reveal that the chaotic behaviors can directly affect the driving comfort and lead to the driver’s comfort being reduced. The obtained results can be used in the design of vehicle and road bumps pavement.

Evaluating the solution from MrBUMP and BALBES

PubMed Central

Keegan, Ronan M.; Long, Fei; Fazio, Vincent J.; Winn, Martyn D.; Murshudov, Garib N.; Vagin, Alexei A.

2011-01-01

Molecular replacement is one of the key methods used to solve the problem of determining the phases of structure factors in protein structure solution from X-ray image diffraction data. Its success rate has been steadily improving with the development of improved software methods and the increasing number of structures available in the PDB for use as search models. Despite this, in cases where there is low sequence identity between the target-structure sequence and that of its set of possible homologues it can be a difficult and time-consuming chore to isolate and prepare the best search model for molecular replacement. MrBUMP and BALBES are two recent developments from CCP4 that have been designed to automate and speed up the process of determining and preparing the best search models and putting them through molecular replacement. Their intention is to provide the user with a broad set of results using many search models and to highlight the best of these for further processing. An overview of both programs is presented along with a description of how best to use them, citing case studies and the results of large-scale testing of the software. PMID:21460449

High-order integral equation methods for problems of scattering by bumps and cavities on half-planes.

PubMed

Pérez-Arancibia, Carlos; Bruno, Oscar P

2014-08-01

This paper presents high-order integral equation methods for the evaluation of electromagnetic wave scattering by dielectric bumps and dielectric cavities on perfectly conducting or dielectric half-planes. In detail, the algorithms introduced in this paper apply to eight classical scattering problems, namely, scattering by a dielectric bump on a perfectly conducting or a dielectric half-plane, and scattering by a filled, overfilled, or void dielectric cavity on a perfectly conducting or a dielectric half-plane. In all cases field representations based on single-layer potentials for appropriately chosen Green functions are used. The numerical far fields and near fields exhibit excellent convergence as discretizations are refined-even at and around points where singular fields and infinite currents exist.

The physics of bump drafting in car racing

NASA Astrophysics Data System (ADS)

Fiolhais, Miguel C. N.; Amor dos Santos, Susana

2014-11-01

The technique of bump drafting, also known as two-car drafting in motorsports, is analysed in the framework of Newtonian mechanics and simple aerodynamic drag forces. As an apparent unnatural effect that often pleases the enthusiasts of car racing, bump drafting provides a unique pedagogical opportunity for students to gain insights into the physics of drag in moving vehicles. In the context of a physics undergraduate course, it is shown that the dynamics of two moving cars in the same air slipstream on a straight line allows them to increase their speed up to a factor of \\sqrt{2} . This conclusion is also extended to an arbitrary number of n identical moving cars, resulting in an increase of \\sqrt{n} .

CFD-Predicted Tile Heating Bump Factors Due to Tile Overlay Repairs

NASA Technical Reports Server (NTRS)

Lessard, Victor R.

2006-01-01

A Computational Fluid Dynamics investigation of the Orbiter's Tile Overlay Repair (TOR) is performed to assess the aeroheating Damage Assessment Team's (DAT) existing heating correlation method for protuberance interference heating on the surrounding thermal protection system. Aerothermodynamic heating analyses are performed for TORs at the design reference damage locations body points 1800 and 1075 for a Mach 17.9 and a=39deg STS-107 flight trajectory point with laminar flow. Six different cases are considered. The computed peak heating bump factor on the surrounding tiles are below the DAT's heating bump factor values for smooth tile cases. However, for the uneven tiles cases the peak interference heating is shown to be considerably higher than the existing correlation prediction.

Novel Heterongineered Detectors for Multi-Color Infrared Sensing

DTIC Science & Technology

2012-01-30

barriers”. Appl. Phys. Lett. 98, 121106 (2011) 9. A. Khoshakhlagh, F. Jaeckel C. Hains J. B. Rodriguez , L. R. Dawson, K. Malloy, and S. Krishna...AlAs etch-stop layer. The detailed processing sequence is included in the Methods. b da c n + -GaAs 200 nm Mesa lndium bump 2.1 –2.1 FPA p d SP-FPA...FPA chip. The processing scheme of the plasmonic FPA chip consists of a dry etch to form the mesa , surface passivation, ohmic metal evaporation, under

PROBING THE ROLE OF CARBON IN ULTRAVIOLET EXTINCTION ALONG GALACTIC SIGHT LINES

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

Parvathi, V. S.; Babu, B. R. S.; Sofia, U. J.

2012-11-20

We report previously undetermined interstellar gas and dust-phase carbon abundances along 15 Galactic sight lines based on archival data of the strong 1334.5323 A transition observed with the Space Telescope Imaging Spectrograph. These are combined with previously reported carbon measurements along six sight lines to produce a complete sample of interstellar C II measurements determined with the 1334 A transition. Our data set includes a variety of Galactic disk environments characterized by different extinctions and samples paths ranging over three orders of magnitude in average density of hydrogen ((n(H))). Our data support the idea that dust, specifically carbon-based grains, aremore » processed in the neutral interstellar medium. We, however, do not find that the abundance of carbon in dust or the grain-size distribution is related to the strength of the 2175 A bump. This is surprising, given that many current models have polycyclic aromatic hydrocarbons as the bump-producing dust.« less

A possible macronova in the late afterglow of the long-short burst GRB 060614.

PubMed

Yang, Bin; Jin, Zhi-Ping; Li, Xiang; Covino, Stefano; Zheng, Xian-Zhong; Hotokezaka, Kenta; Fan, Yi-Zhong; Piran, Tsvi; Wei, Da-Ming

2015-06-11

Long-duration (>2 s) γ-ray bursts that are believed to originate from the death of massive stars are expected to be accompanied by supernovae. GRB 060614, that lasted 102 s, lacks a supernova-like emission down to very stringent limits and its physical origin is still debated. Here we report the discovery of near-infrared bump that is significantly above the regular decaying afterglow. This red bump is inconsistent with even the weakest known supernova. However, it can arise from a Li-Paczyński macronova--the radioactive decay of debris following a compact binary merger. If this interpretation is correct, GRB 060614 arose from a compact binary merger rather than from the death of a massive star and it was a site of a significant production of heavy r-process elements. The significant ejected mass favours a black hole-neutron star merger but a double neutron star merger cannot be ruled out.

Interstellar Silicon Depletion and the Ultraviolet Extinction

NASA Astrophysics Data System (ADS)

Mishra, Ajay; Li, Aigen

2018-01-01

Spinning small silicate grains were recently invoked to account for the Galactic foreground anomalous microwave emission. These grains, if present, will absorb starlight in the far ultraviolet (UV). There is also renewed interest in attributing the enigmatic 2175 Å interstellar extinction bump to small silicates. To probe the role of silicon in the UV extinction, we explore the relations between the amount of silicon required to be locked up in silicates [Si/H]dust and the 2175 Å bump or the far-UV extinction rise, based on an analysis of the extinction curves along 46 Galactic sightlines for which the gas-phase silicon abundance [Si/H]gas is known. We derive [Si/H]dust either from [Si/H]ISM - [Si/H]gas or from the Kramers- Kronig relation which relates the wavelength-integrated extinction to the total dust volume, where [Si/H]ISM is the interstellar silicon reference abundance and taken to be that of proto-Sun or B stars. We also derive [Si/H]dust from fi�tting the observed extinction curves with a mixture of amorphous silicates and graphitic grains. We fi�nd that in all three cases [Si/H]dust shows no correlation with the 2175 Å bump, while the carbon depletion [C/H]dust tends to correlate with the 2175 Å bump. This supports carbon grains instead of silicates as the possible carrier of the 2175 Å bump. We also �find that neither [Si/H]dust nor [C/H]dust alone correlates with the far-UV extinction, suggesting that the far-UV extinction is a combined effect of small carbon grains and silicates.

Interstellar Silicon Depletion and the Ultraviolet Extinction

NASA Astrophysics Data System (ADS)

Mishra, Ajay; Li, Aigen

2017-12-01

Spinning small silicate grains were recently invoked to account for the Galactic foreground anomalous microwave emission. These grains, if present, will absorb starlight in the far-ultraviolet (UV). There is also renewed interest in attributing the enigmatic 2175 \\mathringA interstellar extinction bump to small silicates. To probe the role of silicon in the UV extinction, we explore the relations between the amount of silicon required to be locked up in silicates {[{Si}/{{H}}]}{dust} and the 2175 \\mathringA bump or the far-UV extinction rise, based on an analysis of the extinction curves along 46 Galactic sightlines for which the gas-phase silicon abundance {[{Si}/{{H}}]}{gas} is known. We derive {[{Si}/{{H}}]}{dust} either from {[{Si}/{{H}}]}{ISM}‑{[{Si}/{{H}}]}{gas} or from the Kramers–Kronig relation, which relates the wavelength-integrated extinction to the total dust volume, where {[{Si}/{{H}}]}{ISM} is the interstellar silicon reference abundance and taken to be that of proto-Sun or B stars. We also derive {[{Si}/{{H}}]}{dust} from fitting the observed extinction curves with a mixture of amorphous silicates and graphitic grains. We find that in all three cases {[{Si}/{{H}}]}{dust} shows no correlation with the 2175 \\mathringA bump, while the carbon depletion {[{{C}}/{{H}}]}{dust} tends to correlate with the 2175 \\mathringA bump. This supports carbon grains instead of silicates as the possible carriers of the 2175 \\mathringA bump. We also find that neither {[{Si}/{{H}}]}{dust} nor {[{{C}}/{{H}}]}{dust} alone correlates with the far-UV extinction, suggesting that the far-UV extinction is a combined effect of small carbon grains and silicates.

Qualification test report bump protection hat (subassembly of T020/M509 head protective assembly)

NASA Technical Reports Server (NTRS)

Willis, D. B.

1972-01-01

The bump protection hat (BPH) was subjected to impact testing in which it underwent three impacts at 35 foot-pounds of energy. The impacts generated stress cracks, but no penetration. All impacts resulted in deflections of less than one-half inch. It was shown that the BPH is qualified for Skylab and the rescue vehicle.

Does everything happen when you are young? Introducing the youth bias.

PubMed

Koppel, Jonathan; Berntsen, Dorthe

2014-01-01

The reminiscence bump refers to the disproportionate number of individuals' autobiographical memories that date from young adulthood. A similar bump is found in cultural life scripts: When people are asked to nominate and date major transitional events in a typical life course in their culture, a disproportionate number of the events cited are likewise expected to occur in young adulthood. Across two online studies, we tested whether these effects reflect a broader tendency to ascribe most important events to young adulthood. Specifically, we probed, in adult USA samples, for when individuals expect the most important public event of a typical person's life to take place. Although the occurrence of such public events should be randomly distributed across the lifespan, we found a bump in young adulthood. We found this bump in both subjective (Study 1; probing cultural expectations for the expected timing of the public event that a typical person considers to be the most important of their lifetime) and objective (Study 2; probing cultural expectations for the expected timing of the objectively most important public event of a typical person's lifetime) conditions. We term this set of cultural expectations the youth bias and discuss its implications for human cognition.

New Failure Mode of Flip-Chip Solder Joints Related to the Metallization of an Organic Substrate

NASA Astrophysics Data System (ADS)

Jang, J. W.; Yoo, S. J.; Hwang, H. I.; Yuk, S. Y.; Kim, C. K.; Kim, S. J.; Han, J. S.; An, S. H.

2015-10-01

We report a new failure phenomenon during flip-chip die attach. After reflow, flip-chip bumps were separated between the Al and Ti layers on the Si die side. This was mainly observed at the Si die corner. Transmission electron microscopy images revealed corrosion of the Al layer at the edge of the solder bump metallization. The corrosion at the metallization edge exhibited a notch shape with high stress concentration factor. The organic substrate had Cu metallization with an organic solderable preservative (OSP) coating layer, where a small amount of Cl ions were detected. A solder bump separation mechanism is suggested based on the reaction between Al and Cl, related to the flow of soldering flux. During reflow, the flux will dissolve the Cl-containing OSP layer and flow up to the Al layer on the Si die side. Then, the Cl-dissolved flux will actively react with Al, forming AlCl3. During cooling, solder bumps at the Si die corner will separate through the location of Al corrosion. This demonstrated that the chemistry of the substrate metallization can affect the thermomechanical reliability of flip-chip solder joints.

A Pulsar Wind Nebula Model Applied to Short GRB 050724

NASA Astrophysics Data System (ADS)

Lin, Wei-Li; Wang, Ling-Jun; Dai, Zi-Gao

2018-03-01

A subset of short gamma-ray bursts (sGRBs) have been found to be characterized by near-infrared/optical bumps at ∼1 days, some of which exhibit almost concurrent X-ray flares. Although the near-infrared/optical bumps may be a signature of kilonovae, the X-ray flares are not consistent with kilonovae. It is widely believed that sGRBs are produced by the mergers of double compact objects, during which sub-relativistic ejecta are launched. In this paper, we propose that the above optical/X-ray features are indicative of the formation of long-lived magnetars following the mergers of double neutron stars. Observations and theoretical works imply that the spin-down power of the magnetars is injected into the ejecta as ultra-relativistic electron–positron pairs, i.e., pulsar wind nebulae (PWNe). Here, we suggest such a PWN model and find that the optical bump and X-ray flare observed in GRB 050724 can be well understood in this PWN model. We show that the optical bump and X-ray flare may have different origins. Our results strengthen the evidence for the formation of magnetars in double neutron star mergers and justify the validity of the PWN model.

Understanding Li enhancement in K giants and role of accurate parallaxes

NASA Astrophysics Data System (ADS)

Singh, Raghubar; Reddy, B. E.

2018-04-01

Our recent studies based on a large sample of K giants with Hipparcos parallaxes and spectroscopic analysis resulted more than a dozen new Li-rich K giants including few super Li-rich ones. Most of the Li-rich K giants including the new ones appear to occur at the luminosity bump in the HR diagram. However, one can't rule out the possibility of overlap with the clump region where core He-burning K giants reside post He-flash at the tip of RGB. It is important to distinguish field K giants of clump from the bump region in the HR diagram to understand clues for Li production in K giants. In this poster, we explore whether GAIA parallaxes improve to disentangle clump from bump region, more precisely.

Delta-Doped Back-Illuminated CMOS Imaging Arrays: Progress and Prospects

NASA Technical Reports Server (NTRS)

Hoenk, Michael E.; Jones, Todd J.; Dickie, Matthew R.; Greer, Frank; Cunningham, Thomas J.; Blazejewski, Edward; Nikzad, Shouleh

2009-01-01

In this paper, we report the latest results on our development of delta-doped, thinned, back-illuminated CMOS imaging arrays. As with charge-coupled devices, thinning and back-illumination are essential to the development of high performance CMOS imaging arrays. Problems with back surface passivation have emerged as critical to the prospects for incorporating CMOS imaging arrays into high performance scientific instruments, just as they did for CCDs over twenty years ago. In the early 1990's, JPL developed delta-doped CCDs, in which low temperature molecular beam epitaxy was used to form an ideal passivation layer on the silicon back surface. Comprising only a few nanometers of highly-doped epitaxial silicon, delta-doping achieves the stability and uniformity that are essential for high performance imaging and spectroscopy. Delta-doped CCDs were shown to have high, stable, and uniform quantum efficiency across the entire spectral range from the extreme ultraviolet through the near infrared. JPL has recently bump-bonded thinned, delta-doped CMOS imaging arrays to a CMOS readout, and demonstrated imaging. Delta-doped CMOS devices exhibit the high quantum efficiency that has become the standard for scientific-grade CCDs. Together with new circuit designs for low-noise readout currently under development, delta-doping expands the potential scientific applications of CMOS imaging arrays, and brings within reach important new capabilities, such as fast, high-sensitivity imaging with parallel readout and real-time signal processing. It remains to demonstrate manufacturability of delta-doped CMOS imaging arrays. To that end, JPL has acquired a new silicon MBE and ancillary equipment for delta-doping wafers up to 200mm in diameter, and is now developing processes for high-throughput, high yield delta-doping of fully-processed wafers with CCD and CMOS imaging devices.

Direct Reading Particle Counters: Calibration Verification and Multiple Instrument Agreement via Bump Testing

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

Jankovic, John; Zontek, Tracy L.; Ogle, Burton R.

We examined the calibration records of two direct reading instruments designated as condensation particle counters in order to determine the number of times they were found to be out of tolerance at annual manufacturer's recalibration. For both instruments were found to be out of tolerance more times than within tolerance. And, it was concluded that annual calibration alone was insufficient to provide operational confidence in an instrument's response. Thus, a method based on subsequent agreement with data gathered from a newly calibrated instrument was developed to confirm operational readiness between annual calibrations, hereafter referred to as bump testing. The methodmore » consists of measuring source particles produced by a gas grille spark igniter in a gallon-size jar. Sampling from this chamber with a newly calibrated instrument to determine the calibrated response over the particle concentration range of interest serves as a reference. Agreement between this reference response and subsequent responses at later dates implies that the instrument is performing as it was at the time of calibration. Side-by-side sampling allows the level of agreement between two or more instruments to be determined. This is useful when simultaneously collected data are compared for differences, i.e., background with process aerosol concentrations. A reference set of data was obtained using the spark igniter. The generation system was found to be reproducible and suitable to form the basis of calibration verification. Finally, the bump test is simple enough to be performed periodically throughout the calibration year or prior to field monitoring.« less

Direct Reading Particle Counters: Calibration Verification and Multiple Instrument Agreement via Bump Testing

DOE PAGES

Jankovic, John; Zontek, Tracy L.; Ogle, Burton R.; ...

2015-01-27

We examined the calibration records of two direct reading instruments designated as condensation particle counters in order to determine the number of times they were found to be out of tolerance at annual manufacturer's recalibration. For both instruments were found to be out of tolerance more times than within tolerance. And, it was concluded that annual calibration alone was insufficient to provide operational confidence in an instrument's response. Thus, a method based on subsequent agreement with data gathered from a newly calibrated instrument was developed to confirm operational readiness between annual calibrations, hereafter referred to as bump testing. The methodmore » consists of measuring source particles produced by a gas grille spark igniter in a gallon-size jar. Sampling from this chamber with a newly calibrated instrument to determine the calibrated response over the particle concentration range of interest serves as a reference. Agreement between this reference response and subsequent responses at later dates implies that the instrument is performing as it was at the time of calibration. Side-by-side sampling allows the level of agreement between two or more instruments to be determined. This is useful when simultaneously collected data are compared for differences, i.e., background with process aerosol concentrations. A reference set of data was obtained using the spark igniter. The generation system was found to be reproducible and suitable to form the basis of calibration verification. Finally, the bump test is simple enough to be performed periodically throughout the calibration year or prior to field monitoring.« less

Laser beam joining of optical fibers in silicon V-grooves

NASA Astrophysics Data System (ADS)

Kaufmann, Stefan; Otto, Andreas; Luz, Gerhard

2000-06-01

The increasing use of optical data transmission systems and the development of new optical components require adjustment-insensitive and reliable joining and assembling techniques. The state of the art includes the utilization of silicon submounts with anisotropically etched V-grooves. Several glass fibers are fixed in these V-grooves with adhesive. Adhesive bonds tend towards degradation under the influence of temperature and moisture. For this reason, the alternative joining processes laser beam welding and laser beam soldering are relevant. The goal is a reliable joining of optical fibers in V-grooves without damage to the fibers or the silicon submount. Because of the anomaly of silicon during phase transformation, a positive joining can be realized by laser beam welding. A melt pool is created through the energy of a Nd:YAG-laser pulse. During solidification, the volume of silicon increases and a bump is formed in the center. Experiments have shown that this phenomenon can be used for joining optical fibers in silicon-V-grooves. With suitable parameters the silicon flows half around the fiber during solidification. For each fiber, several welding points are necessary. Another promising joining method is laser bema soldering. In this case, a second silicon sheet with a solder deposit is placed on the fibers which lie in the V-grooves of the metallized silicon submount. The laser heats the upper silicon until the solder metals by heat conduction.

High-speed X-ray imaging pixel array detector for synchrotron bunch isolation

DOE PAGES

Philipp, Hugh T.; Tate, Mark W.; Purohit, Prafull; ...

2016-01-28

A wide-dynamic-range imaging X-ray detector designed for recording successive frames at rates up to 10 MHz is described. X-ray imaging with frame rates of up to 6.5 MHz have been experimentally verified. The pixel design allows for up to 8–12 frames to be stored internally at high speed before readout, which occurs at a 1 kHz frame rate. An additional mode of operation allows the integration capacitors to be re-addressed repeatedly before readout which can enhance the signal-to-noise ratio of cyclical processes. This detector, along with modern storage ring sources which provide short (10–100 ps) and intense X-ray pulses atmore » megahertz rates, opens new avenues for the study of rapid structural changes in materials. The detector consists of hybridized modules, each of which is comprised of a 500 µm-thick silicon X-ray sensor solder bump-bonded, pixel by pixel, to an application-specific integrated circuit. The format of each module is 128 × 128 pixels with a pixel pitch of 150 µm. In the prototype detector described here, the three-side buttable modules are tiled in a 3 × 2 array with a full format of 256 × 384 pixels. Lastly, we detail the characteristics, operation, testing and application of the detector.« less

High-speed X-ray imaging pixel array detector for synchrotron bunch isolation

PubMed Central

Philipp, Hugh T.; Tate, Mark W.; Purohit, Prafull; Shanks, Katherine S.; Weiss, Joel T.; Gruner, Sol M.

2016-01-01

A wide-dynamic-range imaging X-ray detector designed for recording successive frames at rates up to 10 MHz is described. X-ray imaging with frame rates of up to 6.5 MHz have been experimentally verified. The pixel design allows for up to 8–12 frames to be stored internally at high speed before readout, which occurs at a 1 kHz frame rate. An additional mode of operation allows the integration capacitors to be re-addressed repeatedly before readout which can enhance the signal-to-noise ratio of cyclical processes. This detector, along with modern storage ring sources which provide short (10–100 ps) and intense X-ray pulses at megahertz rates, opens new avenues for the study of rapid structural changes in materials. The detector consists of hybridized modules, each of which is comprised of a 500 µm-thick silicon X-ray sensor solder bump-bonded, pixel by pixel, to an application-specific integrated circuit. The format of each module is 128 × 128 pixels with a pixel pitch of 150 µm. In the prototype detector described here, the three-side buttable modules are tiled in a 3 × 2 array with a full format of 256 × 384 pixels. The characteristics, operation, testing and application of the detector are detailed. PMID:26917125

High-speed X-ray imaging pixel array detector for synchrotron bunch isolation.

PubMed

Philipp, Hugh T; Tate, Mark W; Purohit, Prafull; Shanks, Katherine S; Weiss, Joel T; Gruner, Sol M

2016-03-01

A wide-dynamic-range imaging X-ray detector designed for recording successive frames at rates up to 10 MHz is described. X-ray imaging with frame rates of up to 6.5 MHz have been experimentally verified. The pixel design allows for up to 8-12 frames to be stored internally at high speed before readout, which occurs at a 1 kHz frame rate. An additional mode of operation allows the integration capacitors to be re-addressed repeatedly before readout which can enhance the signal-to-noise ratio of cyclical processes. This detector, along with modern storage ring sources which provide short (10-100 ps) and intense X-ray pulses at megahertz rates, opens new avenues for the study of rapid structural changes in materials. The detector consists of hybridized modules, each of which is comprised of a 500 µm-thick silicon X-ray sensor solder bump-bonded, pixel by pixel, to an application-specific integrated circuit. The format of each module is 128 × 128 pixels with a pixel pitch of 150 µm. In the prototype detector described here, the three-side buttable modules are tiled in a 3 × 2 array with a full format of 256 × 384 pixels. The characteristics, operation, testing and application of the detector are detailed.

Development of a 1K x 1K GaAs QWIP Far IR Imaging Array

NASA Technical Reports Server (NTRS)

Jhabvala, M.; Choi, K.; Goldberg, A.; La, A.; Gunapala, S.

2003-01-01

In the on-going evolution of GaAs Quantum Well Infrared Photodetectors (QWIPs) we have developed a 1,024 x 1,024 (1K x1K), 8.4-9 microns infrared focal plane array (FPA). This 1 megapixel detector array is a hybrid using the Rockwell TCM 8050 silicon readout integrated circuit (ROIC) bump bonded to a GaAs QWIP array fabricated jointly by engineers at the Goddard Space Flight Center (GSFC) and the Army Research Laboratory (ARL). The finished hybrid is thinned at the Jet Propulsion Lab. Prior to this development the largest format array was a 512 x 640 FPA. We have integrated the 1K x 1K array into an imaging camera system and performed tests over the 40K-90K temperature range achieving BLIP performance at an operating temperature of 76K (f/2 camera system). The GaAs array is relatively easy to fabricate once the superlattice structure of the quantum wells has been defined and grown. The overall arrays costs are currently dominated by the costs associated with the silicon readout since the GaAs array fabrication is based on high yield, well-established GaAs processing capabilities. In this paper we will present the first results of our 1K x 1K QWIP array development including fabrication methodology, test data and our imaging results.

Imaging performance of a Timepix detector based on semi-insulating GaAs

NASA Astrophysics Data System (ADS)

Zaťko, B.; Zápražný, Z.; Jakůbek, J.; Šagátová, A.; Boháček, P.; Sekáčová, M.; Korytár, D.; Nečas, V.; Žemlička, J.; Mora, Y.; Pichotka, M.

2018-01-01

This work focused on a Timepix chip [1] coupled with a bulk semi-insulating GaAs sensor. The sensor consisted of a matrix of 256 × 256 pixels with a pitch of 55 μm bump-bonded to a Timepix ASIC. The sensor was processed on a 350 μm-thick SI GaAs wafer. We carried out detector adjustment to optimize its performance. This included threshold equalization with setting up parameters of the Timepix chip, such as Ikrum, Pream, Vfbk, and so on. The energy calibration of the GaAs Timepix detector was realized using a 241Am radioisotope in two Timepix detector modes: time-over-threshold and threshold scan. An energy resolution of 4.4 keV in FWHM (Full Width at Half Maximum) was observed for 59.5 keV γ-photons using threshold scan mode. The X-ray imaging quality of the GaAs Timepix detector was tested using various samples irradiated by an X-ray source with a focal spot size smaller than 8 μm and accelerating voltage up to 80 kV. A 700 μm × 700 μm gold testing object (X-500-200-16Au with Siemens star) fabricated with high precision was used for the spatial resolution testing at different values of X-ray image magnification (up to 45). The measured spatial resolution of our X-ray imaging system was about 4 μm.

Recent versus Remote: Flashbulb Memory for 9/11 and Self-Selected Events from the Reminiscence Bump

ERIC Educational Resources Information Center

Denver, Jenny Y.; Lane, Sean M.; Cherry, Katie E.

2010-01-01

In two related studies, we examined flashbulb memories acquired from different points in the lifespan in younger and older adults. When asked to remember flashbulb memories from their lives, older adults were most likely to recall events from the reminiscence bump (Study 1A). In Study 1B, younger and older adults recalled 9/11 and a personal…

Selective inhibition of Sarcocystis neurona calcium-dependent protein kinase 1 for equine protozoal myeloencephalitis therapy.

PubMed

Ojo, Kayode K; Dangoudoubiyam, Sriveny; Verma, Shiv K; Scheele, Suzanne; DeRocher, Amy E; Yeargan, Michelle; Choi, Ryan; Smith, Tess R; Rivas, Kasey L; Hulverson, Matthew A; Barrett, Lynn K; Fan, Erkang; Maly, Dustin J; Parsons, Marilyn; Dubey, Jitender P; Howe, Daniel K; Van Voorhis, Wesley C

2016-12-01

Sarcocystis neurona is the most frequent cause of equine protozoal myeloencephalitis, a debilitating neurological disease of horses that can be difficult to treat. We identified SnCDPK1, the S. neurona homologue of calcium-dependent protein kinase 1 (CDPK1), a validated drug target in Toxoplasma gondii. SnCDPK1 shares the glycine "gatekeeper" residue of the well-characterized T. gondii enzyme, which allows the latter to be targeted by bumped kinase inhibitors. This study presents detailed molecular and phenotypic evidence that SnCDPK1 can be targeted for rational drug development. Recombinant SnCDPK1 was tested against four bumped kinase inhibitors shown to potently inhibit both T. gondii (Tg) CDPK1 and T. gondii tachyzoite growth. SnCDPK1 was inhibited by low nanomolar concentrations of these BKIs and S. neurona growth was inhibited at 40-120nM concentrations. Thermal shift assays confirmed these bumped kinase inhibitors bind CDPK1 in S. neurona cell lysates. Treatment with bumped kinase inhibitors before or after invasion suggests that bumped kinase inhibitors interfere with S. neurona mammalian host cell invasion in the 0.5-2.5μM range but interfere with intracellular division at 2.5μM. In vivo proof-of-concept experiments were performed in a murine model of S. neurona infection. The experimental infected groups treated for 30days with compound BKI-1553 (n=10 mice) had no signs of disease, while the infected control group had severe signs and symptoms of infection. Elevated antibody responses were found in 100% of control infected animals, but only 20% of BKI-1553 treated infected animals. Parasites were found in brain tissues of 100% of the control infected animals, but only in 10% of the BKI-1553 treated animals. The bumped kinase inhibitors used in these assays have been chemically optimized for potency, selectivity and pharmacokinetic properties, and hence are good candidates for treatment of equine protozoal myeloencephalitis. Copyright © 2016 Australian Society for Parasitology. Published by Elsevier Ltd. All rights reserved.

Dust Attenuation Curves in the Local Universe: Demographics and New Laws for Star-forming Galaxies and High-redshift Analogs

NASA Astrophysics Data System (ADS)

Salim, Samir; Boquien, Médéric; Lee, Janice C.

2018-05-01

We study the dust attenuation curves of 230,000 individual galaxies in the local universe, ranging from quiescent to intensely star-forming systems, using GALEX, SDSS, and WISE photometry calibrated on the Herschel ATLAS. We use a new method of constraining SED fits with infrared luminosity (SED+LIR fitting), and parameterized attenuation curves determined with the CIGALE SED-fitting code. Attenuation curve slopes and UV bump strengths are reasonably well constrained independently from one another. We find that {A}λ /{A}V attenuation curves exhibit a very wide range of slopes that are on average as steep as the curve slope of the Small Magellanic Cloud (SMC). The slope is a strong function of optical opacity. Opaque galaxies have shallower curves—in agreement with recent radiative transfer models. The dependence of slopes on the opacity produces an apparent dependence on stellar mass: more massive galaxies have shallower slopes. Attenuation curves exhibit a wide range of UV bump amplitudes, from none to Milky Way (MW)-like, with an average strength one-third that of the MW bump. Notably, local analogs of high-redshift galaxies have an average curve that is somewhat steeper than the SMC curve, with a modest UV bump that can be, to first order, ignored, as its effect on the near-UV magnitude is 0.1 mag. Neither the slopes nor the strengths of the UV bump depend on gas-phase metallicity. Functional forms for attenuation laws are presented for normal star-forming galaxies, high-z analogs, and quiescent galaxies. We release the catalog of associated star formation rates and stellar masses (GALEX–SDSS–WISE Legacy Catalog 2).

A TALE OF TWO MYSTERIES IN INTERSTELLAR ASTROPHYSICS: THE 2175 A EXTINCTION BUMP AND DIFFUSE INTERSTELLAR BANDS

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

Xiang, F. Y.; Zhong, J. X.; Li Aigen, E-mail: jxzhong@xtu.edu.cn, E-mail: lia@missouri.edu

2011-06-01

The diffuse interstellar bands (DIBs) are ubiquitous absorption spectral features arising from the tenuous material in the space between stars-the interstellar medium (ISM). Since their first detection nearly nine decades ago, over 400 DIBs have been observed in the visible and near-infrared wavelength range in both the Milky Way and external galaxies, both nearby and distant. However, the identity of the species responsible for these bands remains as one of the most enigmatic mysteries in astrophysics. An equally mysterious interstellar spectral signature is the 2175 A extinction bump, the strongest absorption feature observed in the ISM. Its carrier also remainsmore » unclear since its first detection 46 years ago. Polycyclic aromatic hydrocarbon (PAH) molecules have long been proposed as a candidate for DIBs as their electronic transitions occur in the wavelength range where DIBs are often found. In recent years, the 2175 A extinction bump is also often attributed to the {pi}-{pi}* transition in PAHs. If PAHs are indeed responsible for both the 2175 A extinction feature and DIBs, their strengths may correlate. We perform an extensive literature search for lines of sight for which both the 2175 A extinction feature and DIBs have been measured. Unfortunately, we found no correlation between the strength of the 2175 A feature and the equivalent widths of the strongest DIBs. A possible explanation might be that DIBs are produced by small free gas-phase PAH molecules and ions, while the 2175 A bump is mainly from large PAHs or PAH clusters in condensed phase so that there is no tight correlation between DIBs and the 2175 A bump.« less

Light curves for bump Cepheids computed with a dynamically zoned pulsation code

NASA Technical Reports Server (NTRS)

Adams, T. F.; Castor, J. I.; Davis, C. G.

1980-01-01

The dynamically zoned pulsation code developed by Castor, Davis, and Davison was used to recalculate the Goddard model and to calculate three other Cepheid models with the same period (9.8 days). This family of models shows how the bumps and other features of the light and velocity curves change as the mass is varied at constant period. The use of a code that is capable of producing reliable light curves demonstrates that the light and velocity curves for 9.8 day Cepheid models with standard homogeneous compositions do not show bumps like those that are observed unless the mass is significantly lower than the 'evolutionary mass.' The light and velocity curves for the Goddard model presented here are similar to those computed independently by Fischel, Sparks, and Karp. They should be useful as standards for future investigators.

NEOS Data and the Origin of the 5 MeV Bump in the Reactor Antineutrino Spectrum

NASA Astrophysics Data System (ADS)

Huber, Patrick

2017-01-01

We perform a combined analysis of recent NEOS and Daya Bay data on the reactor antineutrino spectrum. This analysis includes approximately 1.5 million antineutrino events, which is the largest neutrino event sample analyzed to date. We use a double ratio which cancels flux model dependence and related uncertainties as well as the effects of the detector response model. We find at 3-4 standard deviation significance level, that plutonium-239 and plutonium-241 are disfavored as the single source for the so-called 5 MeV bump. This analysis method has general applicability and, in particular, with higher statistics data sets, will be able to shed significant light on the issue of the bump. With some caveats, this should also allow us to improve the sensitivity for sterile neutrino searches in NEOS.

Equations for predicting internal log defect measurements of common Appalachian hardwoods

Treesearch

Ed Thomas

2016-01-01

As a hardwood tree develops, surface defects such as wounds and branch stubs are overgrown or encapsulated into the tree. Evidence of such a defect remains present on the tree for decades, or for the life of the tree, in the form of bumps and changes in bark pattern. During this process, the appearance of the defect on the tree changes. The defect becomes flatter, the...

Cultivating Our "Musical Bumps" while Fighting the "Progress of Popery": The Rise of Art and Music Education in the Mid-Nineteenth Century United States

ERIC Educational Resources Information Center

Nash, Margaret A.

2013-01-01

This article seeks to understand the social and cultural factors that led to the introduction of music and art education in public schools, a process that began in the middle decades of the nineteenth century. Based on archival material, including institutional catalogues, school board reports, magazine articles, and tracts, I demonstrate that…

Lattice Boltzmann Method of Different BGA Orientations on I-Type Dispensing Method

PubMed Central

Gan, Z. L.; Ishak, M. H. H.; Abdullah, M. Z.; Khor, Soon Fuat

2016-01-01

This paper studies the three dimensional (3D) simulation of fluid flows through the ball grid array (BGA) to replicate the real underfill encapsulation process. The effect of different solder bump arrangements of BGA on the flow front, pressure and velocity of the fluid is investigated. The flow front, pressure and velocity for different time intervals are determined and analyzed for potential problems relating to solder bump damage. The simulation results from Lattice Boltzmann Method (LBM) code will be validated with experimental findings as well as the conventional Finite Volume Method (FVM) code to ensure highly accurate simulation setup. Based on the findings, good agreement can be seen between LBM and FVM simulations as well as the experimental observations. It was shown that only LBM is capable of capturing the micro-voids formation. This study also shows an increasing trend in fluid filling time for BGA with perimeter, middle empty and full orientations. The perimeter orientation has a higher pressure fluid at the middle region of BGA surface compared to middle empty and full orientation. This research would shed new light for a highly accurate simulation of encapsulation process using LBM and help to further increase the reliability of the package produced. PMID:27454872

YIP: Generic Environment Models (GEMs) for Agile Marine Autonomy

DTIC Science & Technology

2013-09-30

2012, and spring 2013, SC for a related NSF project: “Mechanisms of nutrient input at the shelf margin supporting persistent winter phytoplankton blooms...the Shelf Margin Supporting Persistent Winter Phytoplankton Blooms Downstream of the Charleston Bump. We will deploy underwater gliders in Long Bay...SC to study mechanisms of nutrient input at the shelf margin supporting persistent winter phytoplankton blooms downstream of the Charleston Bump. GEM

Detection of solder bump defects on a flip chip using vibration analysis

NASA Astrophysics Data System (ADS)

Liu, Junchao; Shi, Tielin; Xia, Qi; Liao, Guanglan

2012-03-01

Flip chips are widely used in microelectronics packaging owing to the high demand of integration in IC fabrication. Solder bump defects on flip chips are difficult to detect, because the solder bumps are obscured by the chip and substrate. In this paper a nondestructive detection method combining ultrasonic excitation with vibration analysis is presented for detecting missing solder bumps, which is a typical defect in flip chip packaging. The flip chip analytical model is revised by considering the influence of spring mass on mechanical energy of the system. This revised model is then applied to estimate the flip chip resonance frequencies. We use an integrated signal generator and power amplifier together with an air-coupled ultrasonic transducer to excite the flip chips. The vibrations are measured by a laser scanning vibrometer to detect the resonance frequencies. A sensitivity coefficient is proposed to select the sensitive resonance frequency order for defect detection. Finite element simulation is also implemented for further investigation. The results of analytical computation, experiment, and simulation prove the efficacy of the revised flip chip analytical model and verify the effectiveness of this detection method. Therefore, it may provide a guide for the improvement and innovation of the flip chip on-line inspection systems.

Synaptic efficacy shapes resource limitations in working memory.

PubMed

Krishnan, Nikhil; Poll, Daniel B; Kilpatrick, Zachary P

2018-06-01

Working memory (WM) is limited in its temporal length and capacity. Classic conceptions of WM capacity assume the system possesses a finite number of slots, but recent evidence suggests WM may be a continuous resource. Resource models typically assume there is no hard upper bound on the number of items that can be stored, but WM fidelity decreases with the number of items. We analyze a neural field model of multi-item WM that associates each item with the location of a bump in a finite spatial domain, considering items that span a one-dimensional continuous feature space. Our analysis relates the neural architecture of the network to accumulated errors and capacity limitations arising during the delay period of a multi-item WM task. Networks with stronger synapses support wider bumps that interact more, whereas networks with weaker synapses support narrower bumps that are more susceptible to noise perturbations. There is an optimal synaptic strength that both limits bump interaction events and the effects of noise perturbations. This optimum shifts to weaker synapses as the number of items stored in the network is increased. Our model not only provides a circuit-based explanation for WM capacity, but also speaks to how capacity relates to the arrangement of stored items in a feature space.

Coal mine bumps as related to geologic features in the northern part of the Sunnyside District, Carbon County, Utah

USGS Publications Warehouse

Osterwald, Frank W.; Dunrud, C. Richard; Collins, Donley S.

1993-01-01

Coal mine bumps, which are violent, spontaneous, and often catastrophic disruptions of coal and rock, were common in the Sunnyside coal mining district, Utah, before the introduction of protective-engineering methods, modern room-and-pillar retreat mining with continuous mining machines, and particularly modern longwall mining. The coal at Sunnyside, when stressed during mining, fails continuously with many popping, snapping, and banging noises. Although most of the bumps are beneficial because they make mining easier, many of the large ones are dangerous and in the past caused injuries and fatalities, particularly with room- and-pillar mining methods used in the early mining operations. Geologic mapping of underground mine openings revealed many types of deformational features, some pre-mine and some post-mine in age. Stresses resulting from mining are concentrated near the mine openings; if openings are driven at large angles to small pre-mine deformational features, particularly shatter zones in coal, abnormal stress buildups may occur and violent bumps may result. Other geologic features, such as ripple marks, oriented sand grains, intertongued rock contacts, trace fossils, and load casts, also influence the occurrence of bumps by impeding slip of coal and rocks along bedding planes. The stress field in the coal also varies markedly because of the rough ridge and canyon topography. These features may allow excessively large stress components to accumulate. At many places, the stresses that contribute to deformation and failures of mine openings are oriented horizontally. The stratigraphy of the rocks immediately above and below the mined coal bed strongly influences the deformation of the mine openings in response to stress accumulations. Triaxial compressive testing of coal from the Sunnyside No.1 and No.3 Mines indicates that the strength of the coal increases several times as the confining (lateral) stress is increased. Strengths of cores cut from single large blocks of coal vary widely. Although the strengths of coal cores increase slowly at high levels of confining stress, the coal in Sunnyside No. 1 Mine is slightly stronger in laboratory tests than coal in Sunnyside No.3 Mine. The coal in No.1 Mine probably can store larger amounts of stress than coal in the No.3 Mine, which may account for the apparently greater number of violent bumps in No.1 Mine. The strength of coal, and its ability to store stress before failure, may correlate in part with chemical composition, particularly with the amounts of benzene ring compounds in vitrain; coal with relatively large amounts of benzene ring compounds is stronger than coal with lesser amounts of these compounds. Alternatively, the chemical composition of coal may affect its response to stress. Increasing contents of kaolinite in coal appear to reduce its compressive strength at low confining stresses, resulting in easy failures of pillars and ribs in mine openings. Applications of the geologic factors outlined in this report, carefully coupled with advanced modern engineering methods, have markedly reduced the hazards from coal mine bumps and related failures of mine openings at Sunnyside. Similar studies probably could aid in reducing bump-related hazards in other coal mining areas.

Preliminary Results of 3D-DDTC Pixel Detectors for the ATLAS Upgrade

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

La Rosa, Alessandro; /CERN; Boscardin, M.

2012-04-04

3D Silicon sensors fabricated at FBK-irst with the Double-side Double Type Column (DDTC) approach and columnar electrodes only partially etched through p-type substrates were tested in laboratory and in a 1.35 Tesla magnetic field with a 180 GeV pion beam at CERN SPS. The substrate thickness of the sensors is about 200 {mu}m, and different column depths are available, with overlaps between junction columns (etched from the front side) and ohmic columns (etched from the back side) in the range from 110 {mu}m to 150 {mu}m. The devices under test were bump bonded to the ATLAS Pixel readout chip (FEI3)more » at SELEX SI (Rome, Italy). We report leakage current and noise measurements, results of functional tests with Am{sup 241} {gamma}-ray sources, charge collection tests with Sr90 {beta}-source and an overview of preliminary results from the CERN beam test.« less

Tracking Efficiency And Charge Sharing of 3D Silicon Sensors at Different Angles in a 1.4T Magnetic Field

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

Gjersdal, H.; /Oslo U.; Bolle, E.

2012-05-07

A 3D silicon sensor fabricated at Stanford with electrodes penetrating throughout the entire silicon wafer and with active edges was tested in a 1.4 T magnetic field with a 180 GeV/c pion beam at the CERN SPS in May 2009. The device under test was bump-bonded to the ATLAS pixel FE-I3 readout electronics chip. Three readout electrodes were used to cover the 400 {micro}m long pixel side, this resulting in a p-n inter-electrode distance of {approx} 71 {micro}m. Its behavior was confronted with a planar sensor of the type presently installed in the ATLAS inner tracker. Time over threshold, chargemore » sharing and tracking efficiency data were collected at zero and 15{sup o} angles with and without magnetic field. The latest is the angular configuration expected for the modules of the Insertable B-Layer (IBL) currently under study for the LHC phase 1 upgrade expected in 2014.« less

Characterisation of the high dynamic range Large Pixel Detector (LPD) and its use at X-ray free electron laser sources

DOE PAGES

Veale, M. C.; Adkin, P.; Booker, P.; ...

2017-12-04

The STFC Rutherford Appleton Laboratory have delivered the Large Pixel Detector (LPD) for MHz frame rate imaging at the European XFEL. The detector system has an active area of 0.5 m × 0.5 m and consists of a million pixels on a 500 μm pitch. Sensors have been produced from 500 μm thick Hammamatsu silicon tiles that have been bump bonded to the readout ASIC using a silver epoxy and gold stud technique. Each pixel of the detector system is capable of measuring 10 5 12 keV photons per image readout at 4.5 MHz. In this paper results from themore » testing of these detectors at the Diamond Light Source and the Linac Coherent Light Source (LCLS) are presented. As a result, the performance of the detector in terms of linearity, spatial uniformity and the performance of the different ASIC gain stages is characterised.« less

Characterisation of the high dynamic range Large Pixel Detector (LPD) and its use at X-ray free electron laser sources

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

Veale, M. C.; Adkin, P.; Booker, P.

The STFC Rutherford Appleton Laboratory have delivered the Large Pixel Detector (LPD) for MHz frame rate imaging at the European XFEL. The detector system has an active area of 0.5 m × 0.5 m and consists of a million pixels on a 500 μm pitch. Sensors have been produced from 500 μm thick Hammamatsu silicon tiles that have been bump bonded to the readout ASIC using a silver epoxy and gold stud technique. Each pixel of the detector system is capable of measuring 10 5 12 keV photons per image readout at 4.5 MHz. In this paper results from themore » testing of these detectors at the Diamond Light Source and the Linac Coherent Light Source (LCLS) are presented. As a result, the performance of the detector in terms of linearity, spatial uniformity and the performance of the different ASIC gain stages is characterised.« less

Life test of the InGaAs focal plane arrays detector for space applications

NASA Astrophysics Data System (ADS)

Zhu, Xian-Liang; Zhang, Hai-Yan; Li, Xue; Huang, Zhang-Cheng; Gong, Hai-Mei

2017-08-01

The short-wavelength infrared (SWIR) InGaAs focal plane array (FPA) detector consists of infrared detector chip, readout integrated circuit (ROIC), and flip-chip bonding interconnection by Indium bump. In order to satisfy space application requirements for failure rates or Mean Time to Failure (MTTF), which can only be demonstrated with the large number of detectors manufactured, the single pixel in InGaAs FPAs was chosen as the research object in this paper. The constant-stress accelerated life tests were carried out at 70°C 80°C 90°C and100°C. The failed pixels increased gradually during more than 14000 hours at each elevated temperatures. From the random failure data the activation energy was estimated to be 0.46eV, and the average lifetime of a single pixel in InGaAs FPAs was estimated to be longer than 1E+7h at the practical operating temperature (5°C).

Overview of the ATLAS Insertable B-Layer (IBL) Project

NASA Astrophysics Data System (ADS)

Kagan, M. A.

2014-06-01

The first upgrade for the Pixel Detector will be a new pixel layer which is currently under construction and will be installed during the first shutdown of the LHC machine, in 2013-14. The new detector, called the Insertable B-layer (IBL), will be installed between the existing Pixel Detector and a new, smaller radius beam-pipe. Two different silicon sensor technologies, planar n-in-n and 3D, will be used, connected with the new generation 130nm IBM CMOS FE-I4 readout chip via solder bump-bonds. A production quality control test bench was set up in the ATLAS inner detector assembly clean room to verify and rate the performance of the detector elements before integration around the beam-pipe. An overview of the IBL project, of the module design, the qualification for these sensor technologies, the integration quality control setups and recent results in the construction of this full scale new concept detector is discussed.

Simulation studies of plasma waves in the electron foreshock - The generation of Langmuir waves by a gentle bump-on-tail electron distribution

NASA Technical Reports Server (NTRS)

Dum, C. T.

1990-01-01

Particle simulation experiments were used to study the basic physical ingredients needed for building a global model of foreshock wave phenomena. In particular, the generation of Langmuir waves by a gentle bump-on-tail electron distribution is analyzed. It is shown that, with appropriately designed simulations experiments, quasi-linear theory can be quantitatively verified for parameters corresponding to the electron foreshock.

Neural field model of memory-guided search.

PubMed

Kilpatrick, Zachary P; Poll, Daniel B

2017-12-01

Many organisms can remember locations they have previously visited during a search. Visual search experiments have shown exploration is guided away from these locations, reducing redundancies in the search path before finding a hidden target. We develop and analyze a two-layer neural field model that encodes positional information during a search task. A position-encoding layer sustains a bump attractor corresponding to the searching agent's current location, and search is modeled by velocity input that propagates the bump. A memory layer sustains persistent activity bounded by a wave front, whose edges expand in response to excitatory input from the position layer. Search can then be biased in response to remembered locations, influencing velocity inputs to the position layer. Asymptotic techniques are used to reduce the dynamics of our model to a low-dimensional system of equations that track the bump position and front boundary. Performance is compared for different target-finding tasks.

Existence of multi-bump solutions for a class of Kirchhoff type problems in R{sup 3}

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

Liang, Sihua, E-mail: liangsihua@126.com; College of Mathematics, Jilin University, Changchun 130012; Shi, Shaoyun, E-mail: shisy@mail.jlu.edu.cn

2013-12-15

Using variational methods, we establish existence of multi-bump solutions for a class of Kirchhoff type problems −(a+b∫{sub R{sup 3}}|∇u|{sup 2}dx)Δu+λV(x)u=f(u), where f is a continuous function with subcritical growth, V(x) is a critical frequency in the sense that inf{sub x∈R{sup 3}}V(x)=0. We show that if the zero set of V(x) has several isolated connected components Ω{sub 1}, …, Ω{sub k} such that the interior of Ω{sub i} is not empty and ∂Ω{sub i} is smooth, then for λ > 0 large there exists, for any non-empty subset J ⊂ (1, …, k), a bump solution is trapped in a neighborhoodmore » of ∪{sub j∈J}Ω{sub j}.« less

Evaluating bump control techniques through convergence monitoring

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

Campoli, A.A.

1987-07-01

A coal mine bump is the violent failure of a pillar or pillars due to overstress. Retreat coal mining concentrates stresses on the pillars directly outby gob areas, and the situation becomes critical when mining a coalbed encased in rigid associated strata. Bump control techniques employed by the Olga Mine, McDowell County, WV, were evaluated through convergence monitoring in a Bureau of Mines study. Olga uses a novel pillar splitting mining method to extract 55-ft by 70-ft chain pillars, under 1,100 to 1,550 ft of overburden. Three rows of pillars are mined simultaneously to soften the pillar line and reducemore » strain energy storage capacity. Localized stress reduction (destressing) techniques, auger drilling and shot firing, induced approximately 0.1 in. of roof-to-floor convergence in ''high'' -stress pillars near the gob line. Auger drilling of a ''low''-stress pillar located between two barrier pillars produced no convergence effects.« less

Neural field model of memory-guided search

NASA Astrophysics Data System (ADS)

Kilpatrick, Zachary P.; Poll, Daniel B.

2017-12-01

Many organisms can remember locations they have previously visited during a search. Visual search experiments have shown exploration is guided away from these locations, reducing redundancies in the search path before finding a hidden target. We develop and analyze a two-layer neural field model that encodes positional information during a search task. A position-encoding layer sustains a bump attractor corresponding to the searching agent's current location, and search is modeled by velocity input that propagates the bump. A memory layer sustains persistent activity bounded by a wave front, whose edges expand in response to excitatory input from the position layer. Search can then be biased in response to remembered locations, influencing velocity inputs to the position layer. Asymptotic techniques are used to reduce the dynamics of our model to a low-dimensional system of equations that track the bump position and front boundary. Performance is compared for different target-finding tasks.

Artificial plasma cusp generated by upper hybrid instabilities in HF heating experiments at HAARP

NASA Astrophysics Data System (ADS)

Kuo, Spencer; Snyder, Arnold

2013-05-01

High Frequency Active Auroral Research Program digisonde was operated in a fast mode to record ionospheric modifications by the HF heating wave. With the O mode heater of 3.2 MHz turned on for 2 min, significant virtual height spread was observed in the heater off ionograms, acquired beginning the moment the heater turned off. Moreover, there is a noticeable bump in the virtual height spread of the ionogram trace that appears next to the plasma frequency (~ 2.88 MHz) of the upper hybrid resonance layer of the HF heating wave. The enhanced spread and the bump disappear in the subsequent heater off ionograms recorded 1 min later. The height distribution of the ionosphere in the spread situation indicates that both electron density and temperature increases exceed 10% over a large altitude region (> 30 km) from below to above the upper hybrid resonance layer. This "mini cusp" (bump) is similar to the cusp occurring in daytime ionograms at the F1-F2 layer transition, indicating that there is a small ledge in the density profile reminiscent of F1-F2 layer transitions. Two parametric processes exciting upper hybrid waves as the sidebands by the HF heating waves are studied. Field-aligned purely growing mode and lower hybrid wave are the respective decay modes. The excited upper hybrid and lower hybrid waves introduce the anomalous electron heating which results in the ionization enhancement and localized density ledge. The large-scale density irregularities formed in the heat flow, together with the density irregularities formed through the parametric instability, give rise to the enhanced virtual height spread. The results of upper hybrid instability analysis are also applied to explain the descending feature in the development of the artificial ionization layers observed in electron cyclotron harmonic resonance heating experiments.

New PARSEC data base of α-enhanced stellar evolutionary tracks and isochrones - I. Calibration with 47 Tuc (NGC 104) and the improvement on RGB bump

NASA Astrophysics Data System (ADS)

Fu, Xiaoting; Bressan, Alessandro; Marigo, Paola; Girardi, Léo; Montalbán, Josefina; Chen, Yang; Nanni, Ambra

2018-05-01

Precise studies on the Galactic bulge, globular cluster, Galactic halo, and Galactic thick disc require stellar models with α enhancement and various values of helium content. These models are also important for extra-Galactic population synthesis studies. For this purpose, we complement the existing PARSEC models, which are based on the solar partition of heavy elements, with α-enhanced partitions. We collect detailed measurements on the metal mixture and helium abundance for the two populations of 47 Tuc (NGC 104) from the literature, and calculate stellar tracks and isochrones with these α-enhanced compositions. By fitting the precise colour-magnitude diagram with HST ACS/WFC data, from low main sequence till horizontal branch (HB), we calibrate some free parameters that are important for the evolution of low mass stars like the mixing at the bottom of the convective envelope. This new calibration significantly improves the prediction of the red giant branch bump (RGBB) brightness. Comparison with the observed RGB and HB luminosity functions also shows that the evolutionary lifetimes are correctly predicted. As a further result of this calibration process, we derive the age, distance modulus, reddening, and the RGB mass-loss for 47 Tuc. We apply the new calibration and α-enhanced mixtures of the two 47 Tuc populations ([α/Fe] ˜ 0.4 and 0.2) to other metallicities. The new models reproduce the RGB bump observations much better than previous models. This new PARSEC data base, with the newly updated α-enhanced stellar evolutionary tracks and isochrones, will also be a part of the new stellar products for Gaia.

Investigation Of The Effects Of Reflow Profile Parameters On Lead-free Solder Bump Volumes And Joint Integrity

NASA Astrophysics Data System (ADS)

Amalu, E. H.; Lui, Y. T.; Ekere, N. N.; Bhatti, R. S.; Takyi, G.

2011-01-01

The electronics manufacturing industry was quick to adopt and use the Surface Mount Technology (SMT) assembly technique on realization of its huge potentials in achieving smaller, lighter and low cost product implementations. Increasing global customer demand for miniaturized electronic products is a key driver in the design, development and wide application of high-density area array package format. Electronic components and their associated solder joints have reduced in size as the miniaturization trend in packaging continues to be challenged by printing through very small stencil apertures required for fine pitch flip-chip applications. At very narrow aperture sizes, solder paste rheology becomes crucial for consistent paste withdrawal. The deposition of consistent volume of solder from pad-to-pad is fundamental to minimizing surface mount assembly defects. This study investigates the relationship between volume of solder paste deposit (VSPD) and the volume of solder bump formed (VSBF) after reflow, and the effect of reflow profile parameters on lead-free solder bump formation and the associated solder joint integrity. The study uses a fractional factorial design (FFD) of 24-1 Ramp-Soak-Spike reflow profile, with all main effects and two-way interactions estimable to determine the optimal factorial combination. The results from the study show that the percentage change in the VSPD depends on the combination of the process parameters and reliability issues could become critical as the size of solder joints soldered on the same board assembly vary greatly. Mathematical models describe the relationships among VSPD, VSBF and theoretical volume of solder paste. Some factors have main effects across the volumes and a number of interactions exist among them. These results would be useful for R&D personnel in designing and implementing newer applications with finer-pitch interconnect.

Reliability and Characteristics of Wafer-Level Chip-Scale Packages under Current Stress

NASA Astrophysics Data System (ADS)

Chen, Po-Ying; Kung, Heng-Yu; Lai, Yi-Shao; Hsiung Tsai, Ming; Yeh, Wen-Kuan

2008-02-01

In this work, we present a novel approach and method for elucidating the characteristics of wafer-level chip-scale packages (WLCSPs) for electromigration (EM) tests. The die in WLCSP was directly attached to the substrate via a soldered interconnect. The shrinking of the area of the die that is available for power, and the solder bump also shrinks the volume and increases the density of electrons for interconnect efficiency. The bump current density now approaches to 106 A/cm2, at which point the EM becomes a significant reliability issue. As known, the EM failure depends on numerous factors, including the working temperature and the under bump metallization (UBM) thickness. A new interconnection geometry is adopted extensively with moderate success in overcoming larger mismatches between the displacements of components during current and temperature changes. Both environments and testing parameters for WLCSP are increasingly demanded. Although failure mechanisms are considered to have been eliminated or at least made manageable, new package technologies are again challenging its process, integrity and reliability. WLCSP technology was developed to eliminate the need for encapsulation to ensure compatibility with smart-mount technology (SMT). The package has good handing properties but is now facing serious reliability problems. In this work, we investigated the reliability of a WLCSP subjected to different accelerated current stressing conditions at a fixed ambient temperature of 125 °C. A very strong correlation exists between the mean time to failure (MTTF) of the WLCSP test vehicle and the mean current density that is carried by a solder joint. A series of current densities were applied to the WLCSP architecture; Black's power law was employed in a failure mode simulation. Additionally, scanning electron microscopy (SEM) was adopted to determine the differences existing between high- and low-current-density failure modes.

Experiments to measure ablative Richtmyer-Meshkov growth of Gaussian bumps in plastic capsules

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

Loomis, Eric; Batha, Steve; Sedillo, Tom

2010-06-02

Growth of hydrodynamic instabilities at the interfaces of inertial confinement fusion capsules (ICF) due to ablator and fuel non-uniformities have been of primary concern to the ICF program since its inception. To achieve thermonuclear ignition at Megajoule class laser systems such as the NIF, targets must be designed for high implosion velocities, which requires higher in-flight aspect ratios (IFAR) and diminished shell stability. Controlling capsule perturbations is thus of the utmost importance. Recent simulations have shown that features on the outer surface of an ICF capsule as small as 10 microns wide and 100's of nanometers tall such as bumps,more » divots, or even dust particles can profoundly impact capsule performance by leading to material jetting or mix into the hotspot. Recent x-ray images of implosions on the NIF may be evidence of such mixing. Unfortunately, our ability to accurately predict these effects is uncertain due to disagreement between equation of state (EOS) models. In light of this, we have begun a campaign to measure the growth of isolated defects (Gaussian bumps) due to ablative Richtmyer-Meshkov in CH capsules to validate these models. The platform that has been developed uses halfraums with radiation temperatures near 75 eV (Rev. 4 foot-level) driven by 15-20 beams from the Omega laser (Laboratory for Laser Energetics, University of Rochester, NY), which sends a ~2.5 Mbar shock into a planar CH foil. Gaussian-shaped bumps (20 microns wide, 4-7 microns tall) are deposited onto the ablation side of the target. On-axis radiography with a saran (Cl He α - 2.8 keV) backlighter is used to measure bump evolution prior to shock breakout. Shock speed measurements will also be made with Omega's active shock breakout (ASBO) and streaked optical pyrometery (SOP) diagnostics in conjunction with filtered x-ray photodiode arrays (DANTE) to determine drive conditions in the target. These data will be used to discriminate between EOS models so that one may be selected to design the shape and intensity of the foot in an ignition-level drive pulse so that bump amplitude is minimized by the time the shell begins to accelerate.« less

Novel Bonding Technology for Hermetically Sealed Silicon Micropackage

NASA Astrophysics Data System (ADS)

Lee, Duck-Jung; Ju, Byeong-Kwon; Choi, Woo-Beom; Jeong, Jee-Won; Lee, Yun-Hi; Jang, Jin; Lee, Kwang-Bae; Oh, Myung-Hwan

1999-01-01

We performed glass-to-silicon bonding and fabricated a hermetically sealed silicon wafer using silicon direct bonding followed by anodic bonding (SDAB). The hydrophilized glass and silicon wafers in solution were dried and initially bonded in atmosphere as in the silicon direct bonding (SDB) process, but annealing at high temperature was not performed. Anodic bonding was subsequently carried out for the initially bonded specimens. Then the wafer pairs bonded by the SDAB method were different from those bonded by the anodic bonding process only. The effects of the bonding process on the bonded area and tensile strength were investigated as functions of bonding temperature and voltage. Using scanning electron microscopy (SEM), the cross-sectional view of the bonded interface region was observed. In order to investigate the migration of the sodium ions in the bonding process, the concentration of the bonded glass was compared with that of standard glass. The specimen bonded using the SDAB process had higher efficiency than that using the anodic bonding process only.

First survey of Wolf-Rayet star populations over the full extension of nearby galaxies observed with CALIFA

NASA Astrophysics Data System (ADS)

Miralles-Caballero, D.; Díaz, A. I.; López-Sánchez, Á. R.; Rosales-Ortega, F. F.; Monreal-Ibero, A.; Pérez-Montero, E.; Kehrig, C.; García-Benito, R.; Sánchez, S. F.; Walcher, C. J.; Galbany, L.; Iglesias-Páramo, J.; Vílchez, J. M.; González Delgado, R. M.; van de Ven, G.; Barrera-Ballesteros, J.; Lyubenova, M.; Meidt, S.; Falcon-Barroso, J.; Mast, D.; Mendoza, M. A.; Califa Collaboration

2016-08-01

The search of extragalactic regions with conspicuous presence of Wolf-Rayet (WR) stars outside the Local Group is challenging task owing to the difficulty in detecting their faint spectral features. In this exploratory work, we develop a methodology to perform an automated search of WR signatures through a pixel-by-pixel analysis of integral field spectroscopy (IFS) data belonging to the Calar Alto Legacy Integral Field Area survey, CALIFA. This procedure has been applied to a sample of nearby galaxies spanning a wide range of physical, morphological, and environmental properties. This technique allowed us to build the first catalogue of regions rich in WR stars with spatially resolved information, and enabled us to study the properties of these complexes in a two-dimensional (2D) context. The detection technique is based on the identification of the blue WR bump (around He IIλ4686 Å, mainly associated with nitrogen-rich WR stars; WN) and the red WR bump (around C ivλ5808 Å, mainly associated with carbon-rich WR stars; WC) using a pixel-by-pixel analysis that maximizes the number of independent regions within a given galaxy. We identified 44 WR-rich regions with blue bumps distributed in 25 out of a total of 558 galaxies. The red WR bump was identified only in 5 of those regions. Most of the WR regions are located within one effective radius from the galaxy centre, and around one-third are located within ~1 kpc or less from the centre. We found that the majority of the galaxies hosting WR populations in our sample are involved in some kind of interaction process. Half of the host galaxies share some properties with gamma-ray burst (GRB) hosts where WR stars, such as potential candidates to the progenitors of GRBs, are found. We also compared the WR properties derived from the CALIFA data with stellar population synthesis models, and confirm that simple star models are generally not able to reproduce the observations. We conclude that other effects, such as binary star channel (which could extend theWR phase up to 10 Myr), fast rotation, or other physical processes that cause the loss of observed Lyman continuum photons, very likely affect the derived WR properties, and hence should be considered when modelling the evolution of massive stars. Based on observations collected at the Centro Astronómico Hispano-Alemán (CAHA) at Calar Alto, operated jointly by the Max-Planck Institut für Astronomie and the Instituto de Astrofísica de Andalucía (CSIC).

Modified low-temperture direct bonding method for vacuum microelectronics application

NASA Astrophysics Data System (ADS)

Ju, Byeong-Kwon; Lee, Duck-Jung; Choi, Woo-Beom; Lee, Yun-Hi; Jang, Jin; Lee, Kwang-Bae; Oh, Myung-Hwan

1997-06-01

This paper presents the process and experimental results for the improved silicon-to-glass bonding using silicon direct bonding (SDB) followed by anodic bonding. The initial bonding between glass and silicon was caused by the hydrophilic surfaces of silicon-glass ensemble using SDB method. Then the initially bonded specimen had to be strongly bonded by anodic bonding process. The effects of the bonding process parameters on the interface energy were investigated as functions of the bonding temperature and voltage. We found that the specimen which was bonded using SDB process followed by anodic bonding process had higher interface energy than one using anodic bonding process only. The main factor contributing to the higher interface energy in the glass-to-silicon assemble bonded by SDB followed by anodic bonding was investigated by secondary ion mass spectroscopy analysis.

Diagnostic Health Monitoring System Development for Army Vehicle Reliability

DTIC Science & Technology

2011-07-01

19-24 3.4 Receiver Operator Characteristics for fault detection ……………………….. 24-28 3.5 Extended diagnostic speed bump modal data analysis...extended diagnostic speed bump was akin to the use of modal impact testing for exciting broadband frequency ranges in mechanical systems for use in...for a front axle wheel crossing measured using long cleat for ( ) first 30, ( ) second 11, ( ) third 11, ( ) fourth 11, and ( ) fifth 11 data series

Local Sparse Bump Hunting

PubMed Central

Dazard, Jean-Eudes; Rao, J. Sunil

2010-01-01

The search for structures in real datasets e.g. in the form of bumps, components, classes or clusters is important as these often reveal underlying phenomena leading to scientific discoveries. One of these tasks, known as bump hunting, is to locate domains of a multidimensional input space where the target function assumes local maxima without pre-specifying their total number. A number of related methods already exist, yet are challenged in the context of high dimensional data. We introduce a novel supervised and multivariate bump hunting strategy for exploring modes or classes of a target function of many continuous variables. This addresses the issues of correlation, interpretability, and high-dimensionality (p ≫ n case), while making minimal assumptions. The method is based upon a divide and conquer strategy, combining a tree-based method, a dimension reduction technique, and the Patient Rule Induction Method (PRIM). Important to this task, we show how to estimate the PRIM meta-parameters. Using accuracy evaluation procedures such as cross-validation and ROC analysis, we show empirically how the method outperforms a naive PRIM as well as competitive non-parametric supervised and unsupervised methods in the problem of class discovery. The method has practical application especially in the case of noisy high-throughput data. It is applied to a class discovery problem in a colon cancer micro-array dataset aimed at identifying tumor subtypes in the metastatic stage. Supplemental Materials are available online. PMID:22399839

High Resolution N-Body Simulations of Terrestrial Planet Growth

NASA Astrophysics Data System (ADS)

Clark Wallace, Spencer; Quinn, Thomas R.

2018-04-01

We investigate planetesimal accretion with a direct N-body simulation of an annulus at 1 AU around a 1 M_sun star. The planetesimal ring, which initially contains N = 106 bodies is evolved through the runaway growth stage into the phase of oligarchic growth. We find that the mass distribution of planetesimals develops a bump around 1022 g shortly after the oligarchs form. This feature is absent in previous lower resolution studies. We find that this bump marks a boundary between growth modes. Below the bump mass, planetesimals are packed tightly enough together to populate first order mean motion resonances with the oligarchs. These resonances act to heat the tightly packed, low mass planetesimals, inhibiting their growth. We examine the eccentricity evolution of a dynamically hot planetary embryo embedded in an annulus of planetesimals and find that dynamical friction acts more strongly on the embryo when the planetesimals are finely resolved. This effect disappears when the annulus is made narrow enough to exclude most of the mean motion resonances. Additionally, we find that the 1022 g bump is significantly less prominent when we follow planetesimal growth with a skinny annulus.This feature, which is reminiscent of the power law break seen in the size distribution of asteroid belt objects may be an important clue for constraining the initial size of planetesimals in planet formation models.

A Snapshot of the Continuous Emission of the Active Galactic Nucleus in NGC 3783 from Gamma-Ray to Radio Wavelengths

NASA Technical Reports Server (NTRS)

Alloin, D.; Santos-Lleo, M.; Peterson, B. M.; Wamsteker, W.; Altieri, B.; Brinkmann, W.; Clavel, J.; Crenshaw, D. M.; George, I. M.; Glass, I. S.;

When the Desert Beetle Met the Carnivorous Plant: A Perfect Match for Droplet Growth and Shedding

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

Aizenberg, Joanna; Park, Kyoo Chul; Kim, Philseok

2015-01-14

Phase change of vapor followed by coalescence and transport on ubiquitous bumped or curved surfaces is of fundamental importance for a wide range of phenomena and applications from water condensation on cold beverage bottles, to fogging on glasses and windshields, self-cleaning by jumping droplets, weathering, self-assembly, desalination, latent heat transfer, etc. Over the past decades, many attempts to understand and control the droplet growth dynamics and shedding of condensates on textured surfaces have focused on finding the role of micro/nanotexture combined with wettability. In particular, inspired by the Namib desert beetle bump structure, studies tested the effect of topography onmore » the preferential condensation. However, like the preferential condensation observed on flat surfaces, hybrid wettability rather than texture plays a major role; the role of bump topography on local preferential condensation has been unexplored and still not clearly understood. In addition, given that not only facilitating the droplet growth but also transporting the condensed droplets toward the desired reservoir is essential to make fresh sites for renucleation and regrowth of the droplets for enhancing condensation efficiency, the current hybrid-wettability- based design is not efficient to transport the condensates due to the high contact angle hysteresis created by highly wettable pinning points. Here we show that beetle-inspired bump topography leads faster localized condensation and transport of water. Employing simple analytic and more complicated numerical calculations, we reveal the detailed role of topography and predict the focused diffusion flux based on the distortion of concentration gradient around convex surface topography. We experimentally demonstrate the systematic understanding on the unseen effect of topographical parameters on faster droplet growth dynamics on various bump geometries. Further rational design of asymmetric topography and synergetic combination with slippery coating simultaneously enable both faster droplet growth and transport for applications including efficient water condensation.« less

Bumps and Ridges: Trabeculation Effects in Embryonic Heart Development

NASA Astrophysics Data System (ADS)

Battista, Nicholas; Lane, Andrea; Miller, Laura

2014-11-01

Trabeculae form in developing zebrafish hearts for Re on the order of 0.1; effects of trabeculae in this flow is not well understood. Dynamic processes, such as vortex formation, are important in the generation of shear at the endothelial surface layer and strains at the epithelial layer, which aid in proper morphology and functionality. In this study, CFD is used to quantify the effects of Re and idealized trabeculae height on the resulting flows.

Implementation of density-based solver for all speeds in the framework of OpenFOAM

NASA Astrophysics Data System (ADS)

Shen, Chun; Sun, Fengxian; Xia, Xinlin

2014-10-01

In the framework of open source CFD code OpenFOAM, a density-based solver for all speeds flow field is developed. In this solver the preconditioned all speeds AUSM+(P) scheme is adopted and the dual time scheme is implemented to complete the unsteady process. Parallel computation could be implemented to accelerate the solving process. Different interface reconstruction algorithms are implemented, and their accuracy with respect to convection is compared. Three benchmark tests of lid-driven cavity flow, flow crossing over a bump, and flow over a forward-facing step are presented to show the accuracy of the AUSM+(P) solver for low-speed incompressible flow, transonic flow, and supersonic/hypersonic flow. Firstly, for the lid driven cavity flow, the computational results obtained by different interface reconstruction algorithms are compared. It is indicated that the one dimensional reconstruction scheme adopted in this solver possesses high accuracy and the solver developed in this paper can effectively catch the features of low incompressible flow. Then via the test cases regarding the flow crossing over bump and over forward step, the ability to capture characteristics of the transonic and supersonic/hypersonic flows are confirmed. The forward-facing step proves to be the most challenging for the preconditioned solvers with and without the dual time scheme. Nonetheless, the solvers described in this paper reproduce the main features of this flow, including the evolution of the initial transient.

Web-Based Urban Metabolic Mapping for Bangalore, India

NASA Astrophysics Data System (ADS)

Mehta, V. K.; Kemp-Benedict, E.; Wang, G.; Malghan, D.

2012-12-01

Cities are like living entities, needing a continuous throughput of resources and energy for survival and growth, creating waste in the process. This paper documents the Bangalore Urban Mapping Project: an initiative that uses this metabolic concept [1],[2]. to inform comprehensive planning in the rapidly growing software capital of Bangalore city in India. Focusing on demographic growth, and water supply and consumption in its first phase, a web-based geo-portal has been developed for two purposes - interactive information communication and delivery, and online planning in the water supply sector. The application, titled Bangalore Urban Mapping Project (BUMP) is built on a free and open source web GIS stack consisting of a Postgis database, PHP, OpenLayers, and Apache Web Server deployed on a 64-bit Ubuntu Linux server platform. The interactive planning portion of the application allows BUMP users to build, run and visualize demographic growth, water supply, and growth scenarios on the browser. Application logic is written in PHP to connect the many components of the interactive application, which is available on the BUMP website (http://www.seimapping.org/bump/index.php). It relies on AJAX to fetch layer data from the server and render the layer using OpenLayers on the fly. This allows users to view multiple layers at the same time without refreshing the page. Data is packed in GeoJSON format and is compressed to reduce traffic. The information communication portion of the application provides thematic representation of each of twenty different map layers, graphical and tabular summaries of demographic and water data that are presented dynamically using Javascript libraries including the Google Chart API. The application also uses other common Javascript libraries/plug-ins, like jQuery, jQuery UI, qTip, to ease the development and to ensure cross-browser compatibility. The planning portion of the platform allows the user to interact with a scenario explorer through which key aspects of the city's growth, water demand, and supply infrastructure can be entered. This drives a water resources model built on the Water Evaluation And Planning (www.weap21.org) software platform [3] running on a server, that returns key results to the browser. The paper concludes with plans for future development of BUMP, which include crowd-sourcing of water demand and groundwater information, in the face of a critical knowledge gap on both the demand and supply side of the water sector in Indian cities. [1] Newman, P.W.G., 1999. Sustainability and cities: extending the metabolism model. Landscape and urban planning 44, 219-226. [2] Sieferle, R.P., 2011. Cultural Evolution and Social Metabolism. Geografiska Annaler: Series B, Human Geography [3] 93, 315-324. Yates, D., Sieber, J., Purkey, D., Huber-Lee, A., 2005. WEAP21—A Demand-, Priority-, and Preference-Driven Water Planning Model. Water International 30, 487-500.

NASA Tech Briefs, April 2012

NASA Technical Reports Server (NTRS)

2012-01-01

Topics include: Computational Ghost Imaging for Remote Sensing; Digital Architecture for a Trace Gas Sensor Platform; Dispersed Fringe Sensing Analysis - DFSA; Indium Tin Oxide Resistor-Based Nitric Oxide Microsensors; Gas Composition Sensing Using Carbon Nanotube Arrays; Sensor for Boundary Shear Stress in Fluid Flow; Model-Based Method for Sensor Validation; Qualification of Engineering Camera for Long-Duration Deep Space Missions; Remotely Powered Reconfigurable Receiver for Extreme Environment Sensing Platforms; Bump Bonding Using Metal-Coated Carbon Nanotubes; In Situ Mosaic Brightness Correction; Simplex GPS and InSAR Inversion Software; Virtual Machine Language 2.1; Multi-Scale Three-Dimensional Variational Data Assimilation System for Coastal Ocean Prediction; Pandora Operation and Analysis Software; Fabrication of a Cryogenic Bias Filter for Ultrasensitive Focal Plane; Processing of Nanosensors Using a Sacrificial Template Approach; High-Temperature Shape Memory Polymers; Modular Flooring System; Non-Toxic, Low-Freezing, Drop-In Replacement Heat Transfer Fluids; Materials That Enhance Efficiency and Radiation Resistance of Solar Cells; Low-Cost, Rugged High-Vacuum System; Static Gas-Charging Plug; Floating Oil-Spill Containment Device; Stemless Ball Valve; Improving Balance Function Using Low Levels of Electrical Stimulation of the Balance Organs; Oxygen-Methane Thruster; Lunar Navigation Determination System - LaNDS; Launch Method for Kites in Low-Wind or No-Wind Conditions; Supercritical CO2 Cleaning System for Planetary Protection and Contamination Control Applications; Design and Performance of a Wideband Radio Telescope; Finite Element Models for Electron Beam Freeform Fabrication Process Autonomous Information Unit for Fine-Grain Data Access Control and Information Protection in a Net-Centric System; Vehicle Detection for RCTA/ANS (Autonomous Navigation System); Image Mapping and Visual Attention on the Sensory Ego-Sphere; HyDE Framework for Stochastic and Hybrid Model-Based Diagnosis; and IMAGESEER - IMAGEs for Education and Research.

640x512 pixel InGaAs FPAs for short-wave infrared and visible light imaging

NASA Astrophysics Data System (ADS)

Shao, Xiumei; Yang, Bo; Huang, Songlei; Wei, Yang; Li, Xue; Zhu, Xianliang; Li, Tao; Chen, Yu; Gong, Haimei

2017-08-01

The spectral irradiance of moonlight and air glow is mainly in the wavelength region from visible to short-wave infrared (SWIR) band. The imaging over the wavelength range of visible to SWIR is of great significance for applications such as civil safety, night vision, and agricultural sorting. In this paper, 640×512 visible-SWIR InGaAs focal plane arrays (FPAs) were studied for night vision and SWIR imaging. A special epitaxial wafer structure with etch-stop layer was designed and developed. Planar-type 640×512 InGaAs detector arrays were fabricated. The photosensitive arrays were bonded with readout circuit through Indium bumps by flip-chip process. Then, the InP substrate was removed by mechanical thinning and chemical wet etching. The visible irradiance can reach InGaAs absorption layer and then to be detected. As a result, the detection spectrum of the InGaAs FPAs has been extended toward visible spectrum from 0.5μm to 1.7μm. The quantum efficiency is approximately 15% at 0.5μm, 30% at 0.7μm, 50% at 0.8μm, 90% at 1.55μm. The average peak detectivity is higher than 2×1012 cm·Hz1/2/W at room temperature with an integrated time of 10 ms. The Visible-SWIR InGaAs FPAs were applied to an imaging system for SWIR and visible light imaging.

Fabrication of Feedhorn-Coupled Transition Edge Sensor Arrays for Measurement of the Cosmic Microwave Background Polarization

NASA Technical Reports Server (NTRS)

Denis, K. L.; Ali, A.; Appel, J.; Bennett, C. L.; Chang, M. P.; Chuss, D. T.; Colazo, F. A.; Costen, N.; Essinger-Hileman, T.; Hu, R.;

Fabrication of Feedhorn-Coupled Transition Edge Sensor Arrays for Measurement of the Cosmic Microwave Background Polarization

NASA Technical Reports Server (NTRS)

Denis, Kevin L.; Aamir, A.; Bennett, C. L.; Chang, M. P.; Chuss, D. T.; Colazo, F. A.; Costen, N.; Essinger-Hileman, T.; Hu, R.; Marriage, T.;

NASA Tech Briefs, December 2012

NASA Technical Reports Server (NTRS)

2012-01-01

The topics include: Pattern Generator for Bench Test of Digital Boards; 670-GHz Down- and Up-Converting HEMT-Based Mixers; Lidar Electro-Optic Beam Switch with a Liquid Crystal Variable Retarder; Feedback Augmented Sub-Ranging (FASR) Quantizer; Real-Time Distributed Embedded Oscillator Operating Frequency Monitoring; Software Modules for the Proximity-1 Space Link Interleaved Time Synchronization (PITS) Protocol; Description and User Instructions for the Quaternion to Orbit v3 Software; AdapChem; Mars Relay Lander and Orbiter Overflight Profile Estimation; Extended Testability Analysis Tool; Interactive 3D Mars Visualization; Rapid Diagnostics of Onboard Sequences; MER Telemetry Processor; pyam: Python Implementation of YaM; Process for Patterning Indium for Bump Bonding; Archway for Radiation and Micrometeorite Occurrence Resistance; 4D Light Field Imaging System Using Programmable Aperture; Device and Container for Reheating and Sterilization; Radio Frequency Plasma Discharge Lamps for Use as Stable Calibration Light Sources; Membrane Shell Reflector Segment Antenna; High-Speed Transport of Fluid Drops and Solid Particles via Surface Acoustic Waves; Compact Autonomous Hemispheric Vision System; A Distributive, Non-Destructive, Real-Time Approach to Snowpack Monitoring; Wideband Single-Crystal Transducer for Bone Characterization; Numerical Simulation of Rocket Exhaust Interaction With Lunar Soil; Motion Imagery and Robotics Application (MIRA): Standards-Based Robotics; Particle Filtering for Model-Based Anomaly Detection in Sensor Networks; Ka-band Digitally Beamformed Airborne Radar Using SweepSAR Technique; Composite With In Situ Plenums; Multi-Beam Approach for Accelerating Alignment and Calibration of HyspIRI-Like Imaging Spectrometers; JWST Lifting System; Next-Generation Tumbleweed Rover; Pneumatic System for Concentration of Micrometer-Size Lunar Soil.

How can individual differences in autobiographical memory distributions of older adults be explained?

PubMed

Wolf, Tabea; Zimprich, Daniel

2016-10-01

The reminiscence bump phenomenon has frequently been reported for the recall of autobiographical memories. The present study complements previous research by examining individual differences in the distribution of word-cued autobiographical memories. More importantly, we introduce predictor variables that might account for individual differences in the mean (location) and the standard deviation (scale) of individual memory distributions. All variables were derived from different theoretical accounts for the reminiscence bump phenomenon. We used a mixed location-scale logitnormal model, to analyse the 4602 autobiographical memories reported by 118 older participants. Results show reliable individual differences in the location and the scale. After controlling for age and gender, individual proportions of first-time experiences and individual proportions of positive memories, as well as the ratings on Openness to new Experiences and Self-Concept Clarity accounted for 29% of individual differences in location and 42% of individual differences in scale of autobiographical memory distributions. Results dovetail with a life-story account for the reminiscence bump which integrates central components of previous accounts.

Running bumps from stealth bosons

NASA Astrophysics Data System (ADS)

Aguilar-Saavedra, J. A.

2018-03-01

For the `stealth bosons' S, light boosted particles with a decay S → A A → q \\bar{q} q \\bar{q} into four quarks and reconstructed as a single fat jet, the groomed jet mass has a strong correlation with groomed jet substructure variables. Consequently, the jet mass distribution is strongly affected by the jet substructure selection cuts when applied on the groomed jet. We illustrate this fact by recasting a CMS search for low-mass dijet resonances and show a few representative examples. The mass distributions exhibit narrow and wide bumps at several locations in the 100-300 GeV range, between the masses of the daughter particles A and the parent particle S, depending on the jet substructure selection. This striking observation introduces several caveats when interpreting and comparing experimental results, for the case of non-standard signatures. The possibility that a single boosted particle decaying hadronically produces multiple bumps, at quite different jet masses, and depending on the event selection, brings the anomaly chasing game to the next level.

Biomimetic Water-Collecting Fabric with Light-Induced Superhydrophilic Bumps.

PubMed

Wang, Yuanfeng; Wang, Xiaowen; Lai, Chuilin; Hu, Huawen; Kong, Yeeyee; Fei, Bin; Xin, John H

2016-02-10

To develop an efficient water-collecting surface that integrates both fast water-capturing and easy drainage properties is of high current interest for addressing global water issues. In this work, a superhydrophobic surface was fabricated on cotton fabric via manipulation of both the surface roughness and surface energy. This was followed by a subsequent spray coating of TiO2 nanosol that created light-induced superhydrophilic bumps with a unique raised structure as a result of the interfacial tension of the TiO2 nanosol sprayed on the superhydrophobic fiber surface. These raised TiO2 bumps induce both a wettability gradient and a shape gradient, synergistically accelerating water coalescence and water collection. The in-depth study revealed that the quantity and the distribution of the TiO2 had a significant impact on the final water collection efficiency. This inexpensive and facilely fabricated fabric biomimicks the desert beetle's back and spider silk, which are capable of fog harvesting without additional energy consumption.

Cascading reminiscence bumps in popular music.

PubMed

Krumhansl, Carol Lynne; Zupnick, Justin Adam

2013-10-01

Autobiographical memories are disproportionately recalled for events in late adolescence and early adulthood, a phenomenon called the reminiscence bump. Previous studies on music have found autobiographical memories and life-long preferences for music from this period. In the present study, we probed young adults' personal memories associated with top hits over 5-and-a-half decades, as well as the context of their memories and their recognition of, preference for, quality judgments of, and emotional reactions to that music. All these measures showed the typical increase for music released during the two decades of their lives. Unexpectedly, we found that the same measures peaked for the music of participants' parents' generation. This finding points to the impact of music in childhood and suggests that these results reflect the prevalence of music in the home environment. An earlier peak occurred for 1960s music, which may be explained by its quality or by its transmission through two generations. We refer to this pattern of musical cultural transmission over generations as cascading reminiscence bumps.

Ultraviolet Imaging Telescope images of the reflection nebula NGC 7023 - Derivation of ultraviolet scattering properties of dust grains

NASA Technical Reports Server (NTRS)

Witt, Adolf N.; Petersohn, Jens K.; Bohlin, Ralph C.; O'Connell, Robert W.; Roberts, Morton S.; Smith, Andrew M.; Stecher, Theodore P.

1992-01-01

The Ultraviolet Imaging Telescope as part of the Astro-1 mission, was used to obtain high-resolution surface brightness distribution data in six ultraviolet wavelength bands for the bright reflection nebula NGC 7023. From the quantitative comparison of the measured surface brightness gradients ratios of nebular to stellar flux, and detail radial surface brightness profiles with corresponding data from the visible, two major conclusions results: (1) the scattering in the near- and far-ultraviolet in this nebula is more strongly forward-directed than in the visible; (2) the dust albedo in the ultraviolet for wavelengths not less than 140 nm is identical to that in the visible, with the exception of the 220 nm bump in the extinction curve. In the wavelengths region of the bump, the albedo is reduced by 25 to 30 percent in comparison with wavelengths regions both shorter and longer. This lower albedo is expected, if the bump is a pure absorption feature.

Local sparse bump hunting reveals molecular heterogeneity of colon tumors‡

PubMed Central

Dazard, Jean-Eudes; Rao, J. Sunil; Markowitz, Sanford

2013-01-01

The question of molecular heterogeneity and of tumoral phenotype in cancer remains unresolved. To understand the underlying molecular basis of this phenomenon, we analyzed genome-wide expression data of colon cancer metastasis samples, as these tumors are the most advanced and hence would be anticipated to be the most likely heterogeneous group of tumors, potentially exhibiting the maximum amount of genetic heterogeneity. Casting a statistical net around such a complex problem proves difficult because of the high dimensionality and multi-collinearity of the gene expression space, combined with the fact that genes act in concert with one another and that not all genes surveyed might be involved. We devise a strategy to identify distinct subgroups of samples and determine the genetic/molecular signature that defines them. This involves use of the local sparse bump hunting algorithm, which provides a much more optimal and biologically faithful transformed space within which to search for bumps. In addition, thanks to the variable selection feature of the algorithm, we derived a novel sparse gene expression signature, which appears to divide all colon cancer patients into two populations: a population whose expression pattern can be molecularly encompassed within the bump and an outlier population that cannot be. Although all patients within any given stage of the disease, including the metastatic group, appear clinically homogeneous, our procedure revealed two subgroups in each stage with distinct genetic/molecular profiles. We also discuss implications of such a finding in terms of early detection, diagnosis and prognosis. PMID:22052459

Enigmatic Extinction: An Investigation of the 2175Å Extinction Bump in M101

NASA Astrophysics Data System (ADS)

Danowski, Meredith E.; Cook, Timothy; Gordon, Karl D.; Chakrabarti, Supriya; Lawton, Brandon L.; Misselt, Karl A.

2014-06-01

Evidence from studies of starburst galaxies indicates that active formation of high mass stars modifies the UV dust extinction curve as seen by a lack of the characteristic 2175Å bump. For over 45 years, the source of the 2175Å extinction feature has yet to be positively identified. Small aromatic/PAH grains are suggested as a leading contender in dust grain models. The face-on spiral galaxy M101 is an ideal laboratory for the study of dust, with many well-studied HII regions and a steep metallicity and ionization gradient.The Interstellar Medium Absorption Gradient Experiment Rocket (IMAGER) probes the correlation between dust extinction, and the metallicity and radiation environment in M101 at ultraviolet wavelengths. IMAGER simultaneously images M101 in three 400Å-wide bandpasses, measuring the apparent strength of the 2175Å bump and the UV continuum.Combining data from IMAGER with high S/N far- and near- UV observations from the MAMA detectors on the Hubble STIS instrument, we examine the apparent strength of the 2175Å bump in HII regions of M101. With additional infrared data from Spitzer, the DIRTY radiative transfer model, and stellar evolution models, we probe the correlation between the 2175Å feature and the aromatic/PAH features across HII regions of varying metallicity and radiation field hardness. The results of this experiment will directly impact our understanding of the nature of dust and our ability to accurately account for the effects of dust on observations at all redshifts.

What Do We Know About the Ultraviolet Extinction Curve, Fifty Years After the Discovery of the Bump?

NASA Astrophysics Data System (ADS)

Clayton, Geoffrey C.

2012-05-01

It is almost 50 years since Ted Stecher reported the discovery of the 2175 A bump, and almost 25 years since CCM characterized the UV extinction curve as a one-parameter function of R(V), the ratio of total-to-selective extinction. Great strides have been made since then in laboratory, theory, and observation but many questions still remain. The bump is still an unidentified feature, and CCM is not a reliable guide to the wavelength dependence of dust extinction beyond the Milky Way. In fact, the average extinction curve of SMC dust, which has little or no evidence for a 2175 A bump, may be more common in extragalactic environments than Milky Way type dust. The UV extinction curve has been extended to the Lyman limit without any sign in a turnover in the far-UV rise. The old standbys, silicates, graphite, amorphous carbon, and PAH's are still the go-to grain types. But many questions remain about how global properties such as metallicity may lead to large variations in the extinction properties from one galaxy to another. Also of great interest is how dust grains are created, evolve and are destroyed, and in particular, what fraction comes from sources such as evolved stars and supernovae, and what fraction is grown in the ISM. I plan to summarize the role of laboratory and theory can play in better understanding the interstellar dust grains responsible UV extinction.

Subsonic structure and optically thick winds from Wolf-Rayet stars

NASA Astrophysics Data System (ADS)

Grassitelli, L.; Langer, N.; Grin, N. J.; Mackey, J.; Bestenlehner, J. M.; Gräfener, G.

2018-06-01

Mass loss by stellar wind is a key agent in the evolution and spectroscopic appearance of massive main sequence and post-main sequence stars. In Wolf-Rayet stars the winds can be so dense and so optically thick that the photosphere appears in the highly supersonic part of the outflow, veiling the underlying subsonic part of the star, and leaving the initial acceleration of the wind inaccessible to observations. Here we investigate the conditions and the structure of the subsonic part of the outflow of Galactic Wolf-Rayet stars, in particular of the WNE subclass; our focus is on the conditions at the sonic point of their winds. We compute 1D hydrodynamic stellar structure models for massive helium stars adopting outer boundaries at the sonic point. We find that the outflows of our models are accelerated to supersonic velocities by the radiative force from opacity bumps either at temperatures of the order of 200 kK by the iron opacity bump or of the order of 50 kK by the helium-II opacity bump. For a given mass-loss rate, the diffusion approximation for radiative energy transport allows us to define the temperature gradient based purely on the local thermodynamic conditions. For a given mass-loss rate, this implies that the conditions in the subsonic part of the outflow are independent from the detailed physical conditions in the supersonic part. Stellar atmosphere calculations can therefore adopt our hydrodynamic models as ab initio input for the subsonic structure. The close proximity to the Eddington limit at the sonic point allows us to construct a sonic HR diagram, relating the sonic point temperature to the luminosity-to-mass ratio and the stellar mass-loss rate, thereby constraining the sonic point conditions, the subsonic structure, and the stellar wind mass-loss rates of WNE stars from observations. The minimum stellar wind mass-loss rate necessary to have the flow accelerated to supersonic velocities by the iron opacity bump is derived. A comparison of the observed parameters of Galactic WNE stars to this minimum mass-loss rate indicates that these stars have their winds launched to supersonic velocities by the radiation pressure arising from the iron opacity bump. Conversely, stellar models which do not show transonic flows from the iron opacity bump form low-density extended envelopes. We derive an analytic criterion for the appearance of envelope inflation and of a density inversion in the outer sub-photospheric layers.

The neural speed of familiar face recognition.

PubMed

Barragan-Jason, G; Cauchoix, M; Barbeau, E J

2015-08-01

Rapidly recognizing familiar people from their faces appears critical for social interactions (e.g., to differentiate friend from foe). However, the actual speed at which the human brain can distinguish familiar from unknown faces still remains debated. In particular, it is not clear whether familiarity can be extracted from rapid face individualization or if it requires additional time consuming processing. We recorded scalp EEG activity in 28 subjects performing a go/no-go, famous/non-famous, unrepeated, face recognition task. Speed constraints were used to encourage subjects to use the earliest familiarity information available. Event related potential (ERP) analyses show that both the N170 and the N250 components were modulated by familiarity. The N170 modulation was related to behaviour: subjects presenting the strongest N170 modulation were also faster but less accurate than those who only showed weak N170 modulation. A complementary Multi-Variate Pattern Analysis (MVPA) confirmed ERP results and provided some more insights into the dynamics of face recognition as the N170 differential effect appeared to be related to a first transitory phase (transitory bump of decoding power) starting at around 140 ms, which returned to baseline afterwards. This bump of activity was henceforth followed by an increase of decoding power starting around 200 ms after stimulus onset. Overall, our results suggest that rather than a simple single-process, familiarity for faces may rely on a cascade of neural processes, including a coarse and fast stage starting at 140 ms and a more refined but slower stage occurring after 200 ms. Copyright © 2015 Elsevier Ltd. All rights reserved.

Assembly processes comparison for a miniaturized laser used for the Exomars European Space Agency mission

NASA Astrophysics Data System (ADS)

Ribes-Pleguezuelo, Pol; Inza, Andoni Moral; Basset, Marta Gilaberte; Rodríguez, Pablo; Rodríguez, Gemma; Laudisio, Marco; Galan, Miguel; Hornaff, Marcel; Beckert, Erik; Eberhardt, Ramona; Tünnermann, Andreas

2016-11-01

A miniaturized diode-pumped solid-state laser (DPSSL) designed as part of the Raman laser spectrometer (RLS) instrument for the European Space Agency (ESA) Exomars mission 2020 is assembled and tested for the mission purpose and requirements. Two different processes were tried for the laser assembling: one based on adhesives, following traditional laser manufacturing processes; another based on a low-stress and organic-free soldering technique called solderjet bumping technology. The manufactured devices were tested for the processes validation by passing mechanical, thermal cycles, radiation, and optical functional tests. The comparison analysis showed a device improvement in terms of reliability of the optical performances from the soldered to the assembled by adhesive-based means.

Thermal Effectiveness of Wall Indoor Fountain in Warm Humid Climate

NASA Astrophysics Data System (ADS)

Seputra, J. A. P.

2018-03-01

Nowadays, many buildings wield indoor water features such as waterfalls, fountains, and water curtains to improve their aesthetical value. Despite the provision of air cooling due to water evaporation, this feature also has adverse effect if applied in warm humid climate since evaporation might increase air humidity beyond the comfort level. Yet, there are no specific researches intended to measure water feature’s effect upon its thermal condition. In response, this research examines the influence of evaporative cooling on indoor wall fountain toward occupant’s thermal comfort in warm humid climate. To achieve this goal, case study is established in Waroeng Steak Restaurant’s dining room in Surakarta-Indonesia. In addition, SNI 03-6572-2001 with comfort range of 20.5–27.1°C and 40-60% of relative humidity is utilized as thermal criterion. Furthermore, Computational Fluid Dynamics (CFD) is employed to process the data and derive conclusions. Research variables are; feature’s height, obstructions, and fan types. As results, Two Bumps Model (ToB) is appropriate when employs natural ventilation. However, if the room is mechanically ventilated, Three Bumps Model (TeB) becomes the best choice. Moreover, application of adaptive ventilation is required to maintain thermal balance.

Low-stress soldering technique used to assemble an optical system for aerospace missions

NASA Astrophysics Data System (ADS)

Ribes-Pleguezuelo, P.; Koechlin, C.; Burkhardt, T.; Hornaff, M.; Kamm, A.; Gramens, S.; Beckert, E.; Fiault, G.; Eberhardt, R.; Tünnermann, A.

2017-09-01

A high-precision opto-mechanical breadboard for a lens mount has been assembled by means of a laserbased soldering process called Solderjet Bumping; which thanks to its localized and minimized input of thermal energy, is well suited for the joining of optical components made of fragile and brittle materials such as glasses. An optical element made of a silica lens and a titanium barrel has been studied to replicate the lens mounts of the afocal beam expander used in the LIDAR instrument (ATLID) of the ESA EarthCare Mission, whose aim is to monitor molecular and particle-based back-scattering in order to analyze atmosphere composition. Finally, a beam expander optical element breadboard with a silica lens and a titanium barrel was assembled using the Solderjet Bumping technology with Sn96.5Ag3Cu0.5 SAC305 alloy resulting in a low residual stress (<1 MPa) on the joining areas, a low light-depolarization (<0.2 %) and low distortion (wave-front error measurement < 5 nm rms) on the assemblies. The devices also successfully passed humidity, thermal-vacuum, vibration, and shock tests with conditions similar to the ones expected for the ESA EarthCare mission and without altering their optical performances.

Experimental Studies on the Effects of Thermal Bumps in the Flow-Field around a Flat Plate using a Hypersonic Wind Tunnel

DTIC Science & Technology

2012-07-01

Form Approved OMB No. 0704-0188 Public reporting burden for this collection of information is estimated to average 1 hour per response, including the...PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. 1 . REPORT DATE (DD-MM-YYYY) 12 July 2012 2. REPORT TYPE Final Report 3. DATES COVERED...From – To) 1 October 2008 – 31 January 2012 4. TITLE AND SUBTITLE Experimental Studies on the Effects of Thermal Bumps in the Flow-Field around a

On the Existence of Positive Solutions of Semilinear Elliptic Equations.

DTIC Science & Technology

1981-04-01

vt I (0 < p < q < r,0< c <’<) I / -30- OIL - 111.2. Bumps and the shape of the nonlinearity: We want, in this section, to show how bumps or some...8l P L LONS DAAG29-80-C-0041 UNCLASSI RC-TSR-2209wL Eh|IEIIEEEEEEE EElhlEEEEEEEEE I IEEEEIIEEEII ARC echncajSummary Repprt # 2209 QON THE EXISTENCE OF...35P30 Key Words: Semilinear equations, positive solutions, topological degree, bifurcation Work Unit Number I - Applied Analysis *Laboratoire

Short medial approach harvesting of hamstring tendons.

PubMed

Lanternier, H; de Cussac, J B; Collet, T

2016-04-01

Harvesting the hamstring tendons for anterior cruciate ligament reconstruction is not straightforward to perform or to teach: the incision is small, the work-space is narrow and the surgeon's tactile feedback using the stripper is difficult to explain to juniors. The purpose of this short note is to describe a reliable means of harvesting the semitendinosus, gracilis or both. Patient and tourniquet positioning, instrumentation and landmarks are detailed; then the 6 steps (speed-bump 1, speed-bump 2, bubble, hook, expansions, stripper) are explained. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

Numerical Simulation of Transient Liquid Phase Bonding under Temperature Gradient

NASA Astrophysics Data System (ADS)

Ghobadi Bigvand, Arian

Transient Liquid Phase bonding under Temperature Gradient (TG-TLP bonding) is a relatively new process of TLP diffusion bonding family for joining difficult-to-weld aerospace materials. Earlier studies have suggested that in contrast to the conventional TLP bonding process, liquid state diffusion drives joint solidification in TG-TLP bonding process. In the present work, a mass conservative numerical model that considers asymmetry in joint solidification is developed using finite element method to properly study the TG-TLP bonding process. The numerical results, which are experimentally verified, show that unlike what has been previously reported, solid state diffusion plays a major role in controlling the solidification behavior during TG-TLP bonding process. The newly developed model provides a vital tool for further elucidation of the TG-TLP bonding process.

Descemet Stripping Automated Endothelial Keratoplasty for Failed Penetrating Keratoplasty: Influence of the Graft-Host Junction on the Graft Survival Rate.

PubMed

Omoto, Takashi; Sakisaka, Toshihiro; Toyono, Tetsuya; Yoshida, Junko; Shirakawa, Rika; Miyai, Takashi; Yamagami, Satoru; Usui, Tomohiko

2018-04-01

To investigate the clinical results of Descemet stripping automated endothelial keratoplasty (DSAEK) for failed penetrating keratoplasty (PK) and the influence of the graft-host junction (GHJ) on the graft survival rate. Data were retrospectively collected on patient demographics, visual outcomes, complications, and graft survival rate for 17 eyes of 16 patients who underwent DSAEK for failed PK. The graft survival rate was compared between the eyes when divided into a bump group and a well-aligned group according to the shape of the GHJ detected on anterior segment optical coherence tomography. The most common indication for initial PK was bullous keratopathy after glaucoma surgery (35.3%). Seven eyes (41.2%) were classified into the bump group and 10 eyes (58.8%) into the well-aligned group. The mean best-ever documented visual acuity (BDVA) after DSAEK was 0.33 logMAR. Postoperatively, almost 70% of eyes achieved a BDVA that was within 0.2 logMAR of their preoperative BDVA. Graft detachment occurred in 29.4% of eyes and primary graft failure in 17.6%. All primary failures occurred in the bump group. The cumulative graft survival rate was 82.3% at 1 year, 73.2% at 2 years, and 58.6% at 3 years. Graft failure was more likely in eyes in the bump group than in those in the well-aligned group (P = 0.037, Wilcoxon test). DSAEK for failed PK had a favorable outcome in this study. However, the GHJ should be assessed carefully before performing the procedure.

Patterned Polymer Coatings Increase the Efficiency of Dew Harvesting.

PubMed

Al-Khayat, Omar; Hong, Jun Ki; Beck, David M; Minett, Andrew I; Neto, Chiara

2017-04-19

Micropatterned polymer surfaces, possessing both topographical and chemical characteristics, were prepared on three-dimensional copper tubes and used to capture atmospheric water. The micropatterns mimic the structure on the back of a desert beetle that condenses water from the air in a very dry environment. The patterned coatings were prepared by the dewetting of thin films of poly-4-vinylpyridine (P4VP) on top of polystyrene films (PS) films, upon solvent annealing, and consist of raised hydrophilic bumps on a hydrophobic background. The size and density distribution of the hydrophilic bumps could be tuned widely by adjusting the initial thickness of the P4VP films: the diameter of the produced bumps and their height could be varied by almost 2 orders of magnitude (1-80 μm and 40-9000 nm, respectively), and their distribution density could be varied by 5 orders of magnitude. Under low subcooling conditions (3 °C), the highest rate of water condensation was measured on the largest (80 μm diameter) hydrophilic bumps and was found to be 57% higher than that on flat hydrophobic films. These subcooling conditions are achieved spontaneously in dew formation, by passive radiative cooling of a surface exposed to the night sky. In effect, the pattern would result in a larger number of dewy nights than a flat hydrophobic surface and therefore increases water capture efficiency. Our approach is suited to fabrication on a large scale, to enable the use of the patterned coatings for water collection with no external input of energy.

Common mechanisms regulating dark noise and quantum bump amplification in Drosophila photoreceptors

PubMed Central

Chu, Brian; Liu, Che-Hsiung; Sengupta, Sukanya; Gupta, Amit; Raghu, Padinjat

2013-01-01

Absolute visual thresholds are limited by “dark noise,” which in Drosophila photoreceptors is dominated by brief (∼10 ms), small (∼2 pA) inward current events, occurring at ∼2/s, believed to reflect spontaneous G protein activations. These dark events were increased in rate and amplitude by a point mutation in myosin III (NINAC), which disrupts its interaction with the scaffolding protein, INAD. This phenotype mimics that previously described in null mutants of ninaC (no inactivation no afterpotential; encoding myosin III) and an associated protein, retinophilin (rtp). Dark noise was similarly increased in heterozygote mutants of diacylglycerol kinase (rdgA/+). Dark noise in ninaC, rtp, and rdgA/+ mutants was greatly suppressed by mutations of the Gq α-subunit (Gαq) and the major light-sensitive channel (trp) but not rhodopsin. ninaC, rtp, and rdgA/+ mutations also all facilitated residual light responses in Gαq and PLC hypomorphs. Raising cytosolic Ca2+ in the submicromolar range increased dark noise, facilitated activation of transient receptor potential (TRP) channels by exogenous agonist, and again facilitated light responses in Gαq hypomorphs. Our results indicate that RTP, NINAC, INAD, and diacylglycerol kinase, together with a Ca2+-dependent threshold, share common roles in suppressing dark noise and regulating quantum bump generation; consequently, most spontaneous G protein activations fail to generate dark events under normal conditions. By contrast, quantum bump generation is reliable but delayed until sufficient G proteins and PLC are activated to overcome threshold, thereby ensuring generation of full-size bumps with high quantum efficiency. PMID:23365183

Electromigration Failure Mechanism in Sn-Cu Solder Alloys with OSP Cu Surface Finish

NASA Astrophysics Data System (ADS)

Chu, Ming-Hui; Liang, S. W.; Chen, Chih; Huang, Annie T.

2012-09-01

Organic solderable preservative (OSP) has been adopted as the Cu substrate surface finish in flip-chip solder joints for many years. In this study, the electromigration behavior of lead-free Sn-Cu solder alloys with thin-film under bump metallization and OSP surface finish was investigated. The results showed that severe damage occurred on the substrate side (cathode side), whereas the damage on the chip side (cathode side) was not severe. The damage on the substrate side included void formation, copper dissolution, and formation of intermetallic compounds (IMCs). The OSP Cu interface on the substrate side became the weakest point in the solder joint even when thin-film metallization was used on the chip side. Three-dimensional simulations were employed to investigate the current density distribution in the area between the OSP Cu surface finish and the solder. The results indicated that the current density was higher along the periphery of the bonding area between the solder and the Cu pad, consistent with the area of IMC and void formation in our experimental results.

Preparation and characterization of soy protein films with a durable water resistance-adjustable and antimicrobial surface.

PubMed

Li, Shuzhao; Donner, Elizabeth; Xiao, Huining; Thompson, Michael; Zhang, Yachuan; Rempel, Curtis; Liu, Qiang

2016-12-01

A water resistant surface was first obtained by immobilizing hydrophobic copolymers, poly (styrene-co-glycidyl methacrylate) (PSG), with functional groups on soy protein isolate (SPI) films. XPS and AFM results showed that PSG copolymers were immobilized on the film by chemical bonding, and formed a rough surface with some bumps because of the segregation of two different phases on PSG copolymers. Water resistance of the modified films could be adjusted dramatically by further immobilizing different amounts of guanidine-based antimicrobial polymers, poly (hexamethylene guanidine hydrochloride) (PHMG) on the resulting hydrophobic surface. The introduction of hydrophilic PHMG on the resulting surface generated many micropores, which potentially increased the water uptake of the modified films. Furthermore, the modified SPI films showed higher thermostability compared to native SPI film and broad-spectrum antimicrobial activity by contact killing, attributed to the presence of PHMG on the surface. The modified SPI film with a multi-functional surface showed potential for applications in the packaging and medical fields. Crown Copyright © 2016. Published by Elsevier B.V. All rights reserved.

Performance measurements of hybrid PIN diode arrays

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

Jernigan, J.G.; Arens, J.F.; Kramer, G.

We report on the successful effort to develop hybrid PIN diode arrays and to demonstrate their potential as components of vertex detectors. Hybrid pixel arrays have been fabricated by the Hughes Aircraft Co. by bump bonding readout chips developed by Hughes to an array of PIN diodes manufactured by Micron Semiconductor Inc. These hybrid pixel arrays were constructed in two configurations. One array format having 10 {times} 64 pixels, each 120 {mu}m square, and the other format having 256 {times} 256 pixels, each 30 {mu}m square. In both cases, the thickness of the PIN diode layer is 300 {mu}m. Measurementsmore » of detector performance show that excellent position resolution can be achieved by interpolation. By determining the centroid of the charge cloud which spreads charge into a number of neighboring pixels, a spatial resolution of a few microns has been attained. The noise has been measured to be about 300 electrons (rms) at room temperature, as expected from KTC and dark current considerations, yielding a signal-to-noise ratio of about 100 for minimum ionizing particles. 4 refs., 13 figs.« less

High Dynamic Range Pixel Array Detector for Scanning Transmission Electron Microscopy.

PubMed

Tate, Mark W; Purohit, Prafull; Chamberlain, Darol; Nguyen, Kayla X; Hovden, Robert; Chang, Celesta S; Deb, Pratiti; Turgut, Emrah; Heron, John T; Schlom, Darrell G; Ralph, Daniel C; Fuchs, Gregory D; Shanks, Katherine S; Philipp, Hugh T; Muller, David A; Gruner, Sol M

2016-02-01

We describe a hybrid pixel array detector (electron microscope pixel array detector, or EMPAD) adapted for use in electron microscope applications, especially as a universal detector for scanning transmission electron microscopy. The 128×128 pixel detector consists of a 500 µm thick silicon diode array bump-bonded pixel-by-pixel to an application-specific integrated circuit. The in-pixel circuitry provides a 1,000,000:1 dynamic range within a single frame, allowing the direct electron beam to be imaged while still maintaining single electron sensitivity. A 1.1 kHz framing rate enables rapid data collection and minimizes sample drift distortions while scanning. By capturing the entire unsaturated diffraction pattern in scanning mode, one can simultaneously capture bright field, dark field, and phase contrast information, as well as being able to analyze the full scattering distribution, allowing true center of mass imaging. The scattering is recorded on an absolute scale, so that information such as local sample thickness can be directly determined. This paper describes the detector architecture, data acquisition system, and preliminary results from experiments with 80-200 keV electron beams.

Fast Readout Architectures for Large Arrays of Digital Pixels: Examples and Applications

PubMed Central

Gabrielli, A.

2014-01-01

Modern pixel detectors, particularly those designed and constructed for applications and experiments for high-energy physics, are commonly built implementing general readout architectures, not specifically optimized in terms of speed. High-energy physics experiments use bidimensional matrices of sensitive elements located on a silicon die. Sensors are read out via other integrated circuits bump bonded over the sensor dies. The speed of the readout electronics can significantly increase the overall performance of the system, and so here novel forms of readout architectures are studied and described. These circuits have been investigated in terms of speed and are particularly suited for large monolithic, low-pitch pixel detectors. The idea is to have a small simple structure that may be expanded to fit large matrices without affecting the layout complexity of the chip, while maintaining a reasonably high readout speed. The solutions might be applied to devices for applications not only in physics but also to general-purpose pixel detectors whenever online fast data sparsification is required. The paper presents also simulations on the efficiencies of the systems as proof of concept for the proposed ideas. PMID:24778588

Qualification and calibration tests of detector modules for the CMS Pixel Phase 1 upgrade

NASA Astrophysics Data System (ADS)

Zhu, D.; Backhaus, M.; Berger, P.; Meinhard, M.; Starodumov, A.; Tavolaro, V.

2018-01-01

In high energy particle physics, accelerator- and detector-upgrades always go hand in hand. The instantaneous luminosity of the Large Hadron Collider will increase to up to L = 2×1034cm-2s-1 during Run 2 until 2023. In order to cope with such luminosities, the pixel detector of the CMS experiment has been replaced early 2017. The so-called CMS Pixel phase 1 upgrade detector consists of 1184 modules with new design. An important production step is the module qualification and calibration, ensuring their proper functionality within the detector. This paper summarizes the qualification and calibration tests and results of modules used in the innermost two detector layers with focus on methods using module-internal calibration signals. Extended characterizations on pixel level such as electronic noise and bump bond connectivity, optimization of operational parameters, sensor quality and thermal stress resistance were performed using a customized setup with controlled environment. It could be shown that the selected modules have on average 0.55‰ ± 0.01‰ defective pixels and that all performance parameters stay within their specifications.

Corrugated Quantum Well Infrared Photodetector Focal Plane Array Test Results

NASA Technical Reports Server (NTRS)

Goldberg, A.; Choi, K. K.; Das, N. C.; La, A.; Jhabvala, M.

1999-01-01

The corrugated quantum-well infrared photodetector (C-QWIP) uses total internal reflection to couple normal incident light into the optically active quantum wells. The coupling efficiency has been shown to be relatively independent of the pixel size and wavelength thus making the C-QWIP a candidate for detectors over the entire infrared spectrum. The broadband coupling efficiency of the C-QWIP makes it an ideal candidate for multiwavelength detectors. We fabricated and tested C-QWIP focal plane arrays (FPAs) with cutoff wavelengths of 11.2 and 16.2 micrometers. Each FPA has 256 x 256 pixels that are bump-bonded to a direct injection readout circuit. Both FPAs provided infrared imagery with good aesthetic attributes. For the 11.2-micrometers FPA, background-limited performance (BLIP) was observed at 60 K with f/3 optics. For the 16.2-micrometers FPA, BLIP was observed at 38 K. Besides the reduction of dark current in C-QWIP structures, the measured internal quantum efficiency (eta) remains to be high. The values for responsivity and quantum efficiency obtained from the FPA results agree well with those measured for single devices.

Analog signal processing for optical coherence imaging systems

NASA Astrophysics Data System (ADS)

Xu, Wei

Optical coherence tomography (OCT) and optical coherence microscopy (OCM) are non-invasive optical coherence imaging techniques, which enable micron-scale resolution, depth resolved imaging capability. Both OCT and OCM are based on Michelson interferometer theory. They are widely used in ophthalmology, gastroenterology and dermatology, because of their high resolution, safety and low cost. OCT creates cross sectional images whereas OCM obtains en face images. In this dissertation, the design and development of three increasingly complicated analog signal processing (ASP) solutions for optical coherence imaging are presented. The first ASP solution was implemented for a time domain OCT system with a Rapid Scanning Optical Delay line (RSOD)-based optical signal modulation and logarithmic amplifier (Log amp) based demodulation. This OCT system can acquire up to 1600 A-scans per second. The measured dynamic range is 106dB at 200A-scan per second. This OCT signal processing electronics includes an off-the-shelf filter box with a Log amp circuit implemented on a PCB board. The second ASP solution was developed for an OCM system with synchronized modulation and demodulation and compensation for interferometer phase drift. This OCM acquired micron-scale resolution, high dynamic range images at acquisition speeds up to 45,000 pixels/second. This OCM ASP solution is fully custom designed on a perforated circuit board. The third ASP solution was implemented on a single 2.2 mm x 2.2 mm complementary metal oxide semiconductor (CMOS) chip. This design is expandable to a multiple channel OCT system. A single on-chip CMOS photodetector and ASP channel was used for coherent demodulation in a time domain OCT system. Cross-sectional images were acquired with a dynamic range of 76dB (limited by photodetector responsivity). When incorporated with a bump-bonded InGaAs photodiode with higher responsivity, the expected dynamic range is close to 100dB.

Self-sustained oscillations with acoustic feedback in flows over a backward-facing step with a small upstream step

NASA Astrophysics Data System (ADS)

Yokoyama, Hiroshi; Tsukamoto, Yuichi; Kato, Chisachi; Iida, Akiyoshi

2007-10-01

Self-sustained oscillations with acoustic feedback take place in a flow over a two-dimensional two-step configuration: a small forward-backward facing step, which we hereafter call a bump, and a relatively large backward-facing step (backstep). These oscillations can radiate intense tonal sound and fatigue nearby components of industrial products. We clarify the mechanism of these oscillations by directly solving the compressible Navier-Stokes equations. The results show that vortices are shed from the leading edge of the bump and acoustic waves are radiated when these vortices pass the trailing edge of the backstep. The radiated compression waves shed new vortices by stretching the vortex formed by the flow separation at the leading edge of the bump, thereby forming a feedback loop. We propose a formula based on a detailed investigation of the phase relationship between the vortices and the acoustic waves for predicting the frequencies of the tonal sound. The frequencies predicted by this formula are in good agreement with those measured in the experiments we performed.

R package PRIMsrc: Bump Hunting by Patient Rule Induction Method for Survival, Regression and Classification

PubMed Central

Dazard, Jean-Eudes; Choe, Michael; LeBlanc, Michael; Rao, J. Sunil

2015-01-01

PRIMsrc is a novel implementation of a non-parametric bump hunting procedure, based on the Patient Rule Induction Method (PRIM), offering a unified treatment of outcome variables, including censored time-to-event (Survival), continuous (Regression) and discrete (Classification) responses. To fit the model, it uses a recursive peeling procedure with specific peeling criteria and stopping rules depending on the response. To validate the model, it provides an objective function based on prediction-error or other specific statistic, as well as two alternative cross-validation techniques, adapted to the task of decision-rule making and estimation in the three types of settings. PRIMsrc comes as an open source R package, including at this point: (i) a main function for fitting a Survival Bump Hunting model with various options allowing cross-validated model selection to control model size (#covariates) and model complexity (#peeling steps) and generation of cross-validated end-point estimates; (ii) parallel computing; (iii) various S3-generic and specific plotting functions for data visualization, diagnostic, prediction, summary and display of results. It is available on CRAN and GitHub. PMID:26798326

A numerical analysis of shipboard and coastal zone color scanner time series of new production within Gulf Stream cyclonic eddies in the South Atlantic Bight

NASA Technical Reports Server (NTRS)

Pribble, J. Raymond; Walsh, John J.; Dieterle, Dwight A.; Mueller-Karger, Frank E.

1994-01-01

Eddy-induced upwelling occurs along the western edge of the Gulf Stream between Cape Canaveral, Florida, and Cape Hatteras, North Carolina, in the South Atlantic Bight (SAB). Coastal zone color scanner images of 1-km resolution spanning the period April 13-21, 1979, were processed to examine these eddy features in relation to concurrent shipboard and current/temperature measurements at moored arrays. A quasi-one-dimensional (z), time dependent biological model, using only nitrate as a nutrient source, has been combined with a three-dimensional physical model in an attempt to replicate the observed phytoplankton field at the northward edge of an eddy. The model is applicable only to the SAB south of the Charleston Bump, at approximately 31.5 deg N, since no feature analogous to the bump exists in the model bathymetry. The modeled chlorophyll, nitrate, and primary production fields of the euphotic zone are very similar to those obtained from the satellite and shipboard data at the leading edges of the observed eddies south of the Charleston Bump. The horizontal and vertical simulated fluxes of nitrate and chlorophyll show that only approximately 10% of the upwelled nitrate is utilized by the phytoplankton of the modeled grid box on the northern edge of the cyclone, while approximately 75% is lost horizontally, with the remainder still in the euphotic zone after the 10-day period of the model. Loss of chlorophyll due to sinking is very small in this strong upwelling region of the cyclone. The model is relatively insensitive to variations in the sinking parameterization and the external nitrate and chlorophyll fields but is very sensitive to a reduction of the maximum potential growth rate to half that measured. Given the success of this model in simulating the new production of the selcted upwelling region, other upwelling regions for which measurements or successful models of physical and biological quantities and rates exist could be modeled similarly.

Fundamental study of microelectronic chip response under laser ultrasonic-interferometric inspection using C-scan method

NASA Astrophysics Data System (ADS)

Yang, Lei; Gong, Jie; Ume, I. Charles

2014-02-01

In modern surface mount packaging technologies, such as flip chips, chip scale packages, and ball grid arrays(BGA), chips are attached to the substrates/printed wiring board (PWB) using solder bump interconnections. The quality of solder bumps between the chips and the substrate/board is difficult to inspect. Laser ultrasonic-interferometric technique was proved to be a promising approach for solder bump inspection because of its noncontact and nondestructive characteristics. Different indicators extracted from received signals have been used to predict the potential defects, such as correlation coefficient, error ratio, frequency shifting, etc. However, the fundamental understanding of the chip behavior under laser ultrasonic inspection is still missing. Specifically, it is not sure whether the laser interferometer detected out-of-plane displacements were due to wave propagation or structural vibration when the chip was excited by pulsed laser. Plus, it is found that the received signals are chip dependent. Both challenges impede the interpretation of acquired signals. In this paper, a C-scan method was proposed to study the underlying phenomenon during laser ultrasonic inspection. The full chip was inspected. The response of the chip under laser excitation was visualized in a movie resulted from acquired signals. Specifically, a BGA chip was investigated to demonstrate the effectiveness of this method. By characterizing signals using discrete wavelet transform(DWT), both ultrasonic wave propagation and vibration were observed. Separation of them was successfully achieved using ideal band-pass filter and visualized in resultant movies, too. The observed ultrasonic waves were characterized and their respective speeds were measured by applying 2-D FFT. The C-scan method, combined with different digital signal processing techniques, was proved to be an very effective methodology to learn the behavior of chips under laser excitation. This general procedure can be applied to any unknown chip before inspection. A wealth of information can be provided by this learning procedure, which greatly benefits the interpretation of inspection signals afterwards.

Investigation of ball bond integrity for 0.8 mil (20 microns) diameter gold bonding wire on low k die in wire bonding technology

NASA Astrophysics Data System (ADS)

Kudtarkar, Santosh Anil

Microelectronics technology has been undergoing continuous scaling to accommodate customer driven demand for smaller, faster and cheaper products. This demand has been satisfied by using novel materials, design techniques and processes. This results in challenges for the chip connection technology and also the package technology. The focus of this research endeavor was restricted to wire bond interconnect technology using gold bonding wires. Wire bond technology is often regarded as a simple first level interconnection technique. In reality, however, this is a complex process that requires a thorough understanding of the interactions between the design, material and process variables, and their impact on the reliability of the bond formed during this process. This research endeavor primarily focused on low diameter, 0.8 mil thick (20 mum) diameter gold bonding wire. Within the scope of this research, the integrity of the ball bond formed by 1.0 mil (25 mum) and 0.8 mil (20 mum) diameter wires was compared. This was followed by the evaluation of bonds formed on bond pads having doped SiO2 (low k) as underlying structures. In addition, the effect of varying the percentage of the wire dopant, palladium and bonding process parameters (bonding force, bond time, ultrasonic energy) for 0.8 mil (20 mum) bonding wire was also evaluated. Finally, a degradation empirical model was developed to understand the decrease in the wire strength. This research effort helped to develop a fundamental understanding of the various factors affecting the reliability of a ball bond from a design (low diameter bonding wire), material (low k and bonding wire dopants), and process (wire bonding process parameters) perspective for a first level interconnection technique, namely wire bonding. The significance of this research endeavor was the systematic investigation of the ball bonds formed using 0.8 mil (20 microm) gold bonding wire within the wire bonding arena. This research addressed low k structures on 90 nm silicon technology, bonding wires with different percentage of doping element (palladium), and different levels of bonding process parameters. An empirical model to understand the high temperature effects for bonds formed using the low diameter wire was also developed.

Numerical studies of nonspherical carbon combustion models

NASA Astrophysics Data System (ADS)

Mueller, E.; Arnett, W. D.

1982-10-01

First results of axisymmetric numerical studies of the final evolution of degenerate C + O cores are reported. The two-dimensional convective flow is treated without a phenomenological theory of convection. The computations show that, in the beginning, the nuclear burning propagates slowly outward from the center of the star in a spherical combustion front. Small-scale eddies form, giving rise to bumps in the front. The bumps grow into blobs and eventually into fingers, which steadily elongate relative to the rest of the combustion front. This behavior is not well described by either the detonation or deflagration models, being more complex than either.

Interpretation of OAO-2 ultraviolet light curves of beta Doradus

NASA Technical Reports Server (NTRS)

Hutchinson, J. L.; Lillie, C. F.; Hill, S. J.

1975-01-01

Middle-ultraviolet light curves of beta Doradus, obtained by OAO-2, are presented along with other evidence indicating that the small additional bumps observed on the rising branches of these curves have their origin in shock-wave phenomena in the upper atmosphere of this classical Cepheid. A simple piston-driven spherical hydrodynamic model of the atmosphere is developed to explain the bumps, and the calculations are compared with observations. The model is found to be consistent with the shapes of the light curves as well as with measurements of the H-alpha radial velocities.

Topographic coupling of surface and internal Kelvin waves. [of ocean

NASA Technical Reports Server (NTRS)

Chao, S.-Y.

1980-01-01

An analysis is presented for computing the diffraction of barotropic Kelvin waves by a localized topographical irregularity on flat-bottom ocean with an arbitrary vertical stratification. It was shown that all baroclinic Kelvin waves will be generated downstream of the bump, with the first baroclinic mode having the largest amplitude. The Poincare waves predominate in the lowest modes, and are more directionally anisotropic. It was concluded that baroclinic Poincare waves radiating offshore from the bump topography could contribute to the internal wave field in the open ocean and provide an alternative mechanism to dissipate the barotropic tides.

Flexure Bearing Reduces Startup Friction

NASA Technical Reports Server (NTRS)

Clingman, W. Dean

1991-01-01

Design concept for ball bearing incorporates small pieces of shim stock, wire spokes like those in bicycle wheels, or other flexing elements to reduce both stiction and friction slope. In flexure bearing, flexing elements placed between outer race of ball bearing and outer ring. Elements flex when ball bearings encounter small frictional-torque "bumps" or even larger ones when bearing balls encounter buildups of grease on inner or outer race. Flexure of elements reduce high friction slopes of "bumps", helping to keep torque between outer ring and inner race low and more nearly constant. Concept intended for bearings in gimbals on laser and/or antenna mirrors.

Gamma ray astronomy and black hole astrophysics

NASA Technical Reports Server (NTRS)

Liang, Edison P.

1990-01-01

The study of soft gamma emissions from black-hole candidates is identified as an important element in understanding black-hole phenomena ranging from stellar-mass black holes to AGNs. The spectra of Cyg X-1 and observations of the Galactic Center are emphasized, since thermal origins and MeV gamma-ray bumps are evident and suggest a thermal-pair cloud picture. MeV gamma-ray observations are suggested for studying black hole astrophysics such as the theorized escaping pair wind, the anticorrelation between the MeV gamma bump and the soft continuum, and the relationship between source compactness and temperature.

Performance comparison of small-pixel CdZnTe radiation detectors with gold contacts formed by sputter and electroless deposition

NASA Astrophysics Data System (ADS)

Bell, S. J.; Baker, M. A.; Duarte, D. D.; Schneider, A.; Seller, P.; Sellin, P. J.; Veale, M. C.; Wilson, M. D.

2017-06-01

Recent improvements in the growth of wide-bandgap semiconductors, such as cadmium zinc telluride (CdZnTe or CZT), has enabled spectroscopic X/γ-ray imaging detectors to be developed. These detectors have applications covering homeland security, industrial analysis, space science and medical imaging. At the Rutherford Appleton Laboratory (RAL) a promising range of spectroscopic, position sensitive, small-pixel Cd(Zn)Te detectors have been developed. The challenge now is to improve the quality of metal contacts on CdZnTe in order to meet the demanding energy and spatial resolution requirements of these applications. The choice of metal deposition method and fabrication process are of fundamental importance. Presented is a comparison of two CdZnTe detectors with contacts formed by sputter and electroless deposition. The detectors were fabricated with a 74 × 74 array of 200 μm pixels on a 250 μm pitch and bump-bonded to the HEXITEC ASIC. The X/γ-ray emissions from an 241Am source were measured to form energy spectra for comparison. It was found that the detector with contacts formed by electroless deposition produced the best uniformity and energy resolution; the best pixel produced a FWHM of 560 eV at 59.54 keV and 50% of pixels produced a FWHM better than 1.7 keV . This compared with a FWHM of 1.5 keV for the best pixel and 50% of pixels better than 4.4 keV for the detector with sputtered contacts.

Radiation Belt Electron Energy Spectra Characterization and Evolution Based on the Van Allen Probes Measurements

NASA Astrophysics Data System (ADS)

Zhao, H.; Baker, D. N.; Jaynes, A. N.; Li, X.; Kanekal, S. G.; Blum, L. W.; Schiller, Q. A.; Leonard, T. W.; Elkington, S. R.

2017-12-01

The electron energy spectra, as an important characteristic of radiation belt electrons, provide valuable information on the physical mechanisms affecting different electron populations. Based on the measurements of 30 keV - 10 MeV electrons from MagEIS and REPT instruments on the Van Allen Probes, case studies and statistical analysis of the radiation belt electron energy spectra characterization and evolution have been performed. Generally the radiation belt electron energy spectra can be represented by one of the three types of distributions: exponential, power law, and bump-on-tail. Statistical analysis shows that the exponential spectra are usually dominant in the outer radiation belt; as the geomagnetic storms occur, energy spectra in the outer belt soften at first due to injection of lower-energy electrons and loss of higher-energy electrons, and gradually get harder due to loss of lower-energy electrons and delayed enhancement of higher energy electron fluxes. Power law spectra generally dominate the inner belt and higher L region (L>6) during injections. Bump-on-tail spectra commonly exist inside the plasmasphere following the geomagnetic storms and/or the compression of plasmasphere, while the energy of flux maxima is usually 1.8 MeV as the bump-on-tail spectra form and gradually moves to higher energies as the spectra evolve, with the ratio of flux maxima to minima up to >10. Detailed event study indicates that the appearance of bump-on-tail spectra are mainly due to energy-dependent losses caused by the plasmaspheric hiss wave scattering, while the disappearance of these spectra can be attributed to fast flux enhancements of lower-energy electrons during storms.

Study on the mechanism of Si-glass-Si two step anodic bonding process

NASA Astrophysics Data System (ADS)

Hu, Lifang; Wang, Hao; Xue, Yongzhi; Shi, Fangrong; Chen, Shaoping

2018-04-01

Si-glass-Si was successfully bonded together through a two-step anodic bonding process. The bonding current in each step of the two-step bonding process was investigated, and found to be quite different. The first bonding current decreased quickly to a relatively small value, but for the second bonding step, there were two current peaks; the current first decreased, then increased, and then decreased again. The second current peak occurred earlier with higher temperature and voltage. The two-step anodic bonding process was investigated in terms of bonding current. SEM and EDS tests were conducted to investigate the interfacial structure of the Si-glass-Si samples. The two bonding interfaces were almost the same, but after an etching process, transitional layers could be found in the bonding interface and a deeper trench with a thickness of ~1.5 µm could be found in the second bonding interface. Atomic force microscopy mapping results indicated that sodium precipitated from the back of the glass, which makes the roughness of the surface become coarse. Tensile tests indicated that the fracture occurred at the glass substrate and that the bonding strength increased with the increment of bonding temperature and voltage with the maximum strength of 6.4 MPa.

Unsteady features of the flow on a bump in transonic environment

NASA Astrophysics Data System (ADS)

Budovsky, A. D.; Sidorenko, A. A.; Polivanov, P. A.; Vishnyakov, O. I.; Maslov, A. A.

2016-10-01

The study deals with experimental investigation of unsteady features of separated flow on a profiled bump in transonic environment. The experiments were conducted in T-325 wind tunnel of ITAM for the following flow conditions: P0 = 1 bar, T0 = 291 K. The base flow around the model was studied by schlieren visualization, steady and unsteady wall pressure measurements and PIV. The experimentally data obtained using PIV are analyzed by Proper Orthogonal Decomposition (POD) technique to investigate the underlying unsteady flow organization, as revealed by the POD eigenmodes. The data obtained show that flow pulsations revealed upstream and downstream of shock wave are correlated and interconnected.

PROBING ELECTRON-CAPTURE SUPERNOVAE: X-RAY BINARIES IN STARBURSTS

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

Linden, T.; Sepinsky, J. F.; Kalogera, V.

We develop population models of high-mass X-ray binaries (HMXBs) formed after bursts of star formation and we investigate the effect of electron-capture supernovae (ECS) of massive ONeMg white dwarfs and the hypothesis that ECS events are associated with typically low supernova kicks imparted to the nascent neutron stars. We identify an interesting ECS bump in the time evolution of HMXB numbers; this bump is caused by significantly increased production of wind-fed HMXBs 20-60 Myr post-starburst. The amplitude and age extent of the ECS bump depend on the strength of ECS kicks and the mass range of ECS progenitors. We alsomore » find that ECS-HMXBs form through a specific evolutionary channel that is expected to lead to binaries with Be donors in wide orbits. These characteristics, along with their sensitivity to ECS properties, provide us with an intriguing opportunity to probe ECS physics and progenitors through studies of starbursts of different ages. Specifically, the case of the Small Magellanic Cloud, with a significant observed population of Be-HMXBs and starburst activity 30-60 Myr ago, arises as a promising laboratory for understanding the role of ECS in neutron star formation.« less

Multiple Fingers - One Gestalt.

PubMed

Lezkan, Alexandra; Manuel, Steven G; Colgate, J Edward; Klatzky, Roberta L; Peshkin, Michael A; Drewing, Knut

2016-01-01

The Gestalt theory of perception offered principles by which distributed visual sensations are combined into a structured experience ("Gestalt"). We demonstrate conditions whereby haptic sensations at two fingertips are integrated in the perception of a single object. When virtual bumps were presented simultaneously to the right hand's thumb and index finger during lateral arm movements, participants reported perceiving a single bump. A discrimination task measured the bump's perceived location and perceptual reliability (assessed by differential thresholds) for four finger configurations, which varied in their adherence to the Gestalt principles of proximity (small versus large finger separation) and synchrony (virtual spring to link movements of the two fingers versus no spring). According to models of integration, reliability should increase with the degree to which multi-finger cues integrate into a unified percept. Differential thresholds were smaller in the virtual-spring condition (synchrony) than when fingers were unlinked. Additionally, in the condition with reduced synchrony, greater proximity led to lower differential thresholds. Thus, with greater adherence to Gestalt principles, thresholds approached values predicted for optimal integration. We conclude that the Gestalt principles of synchrony and proximity apply to haptic perception of surface properties and that these principles can interact to promote multi-finger integration.

Adaptations for vision in dim light: impulse responses and bumps in nocturnal spider photoreceptor cells (Cupiennius salei Keys).

PubMed

Pirhofer-Walzl, Karin; Warrant, Eric; Barth, Friedrich G

2007-10-01

The photoreceptor cells of the nocturnal spider Cupiennius salei were investigated by intracellular electrophysiology. (1) The responses of photoreceptor cells of posterior median (PM) and anterior median (AM) eyes to short (2 ms) light pulses showed long integration times in the dark-adapted and shorter integration times in the light-adapted state. (2) At very low light intensities, the photoreceptors responded to single photons with discrete potentials, called bumps, of high amplitude (2-20 mV). When measured in profoundly dark-adapted photoreceptor cells of the PM eyes these bumps showed an integration time of 128 +/- 35 ms (n = 7) whereas in dark-adapted photoreceptor cells of AM eyes the integration time was 84 +/- 13 ms (n = 8), indicating that the AM eyes are intrinsically faster than the PM eyes. (3) Long integration times, which improve visual reliability in dim light, and large responses to single photons in the dark-adapted state, contribute to a high visual sensitivity in Cupiennius at night. This conclusion is underlined by a calculation of sensitivity that accounts for both anatomical and physiological characteristics of the eye.

Can the bump in the composite spectrum of GRB 910503 be an emission line feature of gamma-ray bursts?

NASA Astrophysics Data System (ADS)

Qin, Yi-Ping; Zhang, Fu-Wen

2005-12-01

Appearing in the composite spectral data of BATSE, EGRET and COMPTEL for GRB 910503, there is a bump at around 1600 keV. We perform a statistical analysis on the spectral data, trying to find out if the bump could be accounted for by a blue-shifted and significantly broadened rest frame line due to the Doppler effect of an expanding fireball surface. We made an F-test and adopted previously proposed criteria. The study reveals that the criteria are well satisfied and the feature can be interpreted as the blue shifted 6.4 keV line. From the fit with this line taken into account, we find the Lorentz factor of this source to be Γ = 116+9-9 (at the 68% confident level, triangleχ2 = 1) and the rest frame spectral peak energy to be E0,p = 2.96+0.24-0.18 keV. Although the existence of the emission line feature requires other independent tests to confirm, the analysis suggests that it is feasible to detect emission line features in the high energy range of GRB spectra when taking into account the Doppler effect of fireball expansion.

The application of Markov decision process with penalty function in restaurant delivery robot

NASA Astrophysics Data System (ADS)

Wang, Yong; Hu, Zhen; Wang, Ying

2017-05-01

As the restaurant delivery robot is often in a dynamic and complex environment, including the chairs inadvertently moved to the channel and customers coming and going. The traditional Markov decision process path planning algorithm is not save, the robot is very close to the table and chairs. To solve this problem, this paper proposes the Markov Decision Process with a penalty term called MDPPT path planning algorithm according to the traditional Markov decision process (MDP). For MDP, if the restaurant delivery robot bumps into an obstacle, the reward it receives is part of the current status reward. For the MDPPT, the reward it receives not only the part of the current status but also a negative constant term. Simulation results show that the MDPPT algorithm can plan a more secure path.

31 CFR 224.3 - When may a surety corporation provide a bond without appointing a process agent?

Code of Federal Regulations, 2011 CFR

2011-07-01

... MANAGEMENT SERVICE FEDERAL PROCESS AGENTS OF SURETY CORPORATIONS § 224.3 When may a surety corporation provide a bond without appointing a process agent? A surety corporation may provide a bond without... a bond without appointing a process agent? 224.3 Section 224.3 Money and Finance: Treasury...

Analysis of factors influencing the bond strength in roll bonding processes

NASA Astrophysics Data System (ADS)

Khaledi, Kavan; Wulfinghoff, Stephan; Reese, Stefanie

2018-05-01

Cold Roll Bonding (CRB) is recognized as an industrial technique in which the metal sheets are joined together in order to produce laminate metal composites. In this technique, a metallurgical bond resulting from severe plastic deformation is formed between the rolled metallic layers. The main objective of this paper is to analyse different factors which may affect the bond formation in rolling processes. To achieve this goal, first, an interface model is employed which describes both the bonding and debonding. In this model, the bond strength evolution between the metallic layers is calculated based on the film theory of bonding. On the other hand, the debonding process is modelled by means of a bilinear cohesive zone model. In the numerical section, different scenarios are taken into account to model the roll bonding process of metal sheets. The numerical simulation includes the modelling of joining during the roll bonding process followed by debonding in a Double Cantilever Beam (DCB) peeling test. In all simulations, the metallic layers are regarded as elastoplastic materials subjected to large plastic deformations. Finally, the effects of some important factors on the bond formation are numerically investigated.

GOODS-Herschel: dust attenuation properties of UV selected high redshift galaxies

NASA Astrophysics Data System (ADS)

Buat, V.; Noll, S.; Burgarella, D.; Giovannoli, E.; Charmandaris, V.; Pannella, M.; Hwang, H. S.; Elbaz, D.; Dickinson, M.; Magdis, G.; Reddy, N.; Murphy, E. J.

2012-09-01

Context. Dust attenuation in galaxies is poorly known, especially at high redshift. And yet the amount of dust attenuation is a key parameter to deduce accurate star formation rates from ultraviolet (UV) rest-frame measurements. The wavelength dependence of the dust attenuation is also of fundamental importance to interpret the observed spectral energy distributions (SEDs) and to derive photometric redshifts or physical properties of galaxies. Aims: We want to study dust attenuation at UV wavelengths at high redshift, where the UV is redshifted to the observed visible light wavelength range. In particular, we search for a UV bump and related implications for dust attenuation determinations. Methods: We use photometric data in the Chandra Deep Field South (CDFS), obtained in intermediate and broad band filters by the MUSYC project, to sample the UV rest-frame of 751 galaxies with 0.95 < z < 2.2. When available, infrared (IR) Herschel/PACS data from the GOODS-Herschel project, coupled with Spitzer/MIPS measurements, are used to estimate the dust emission and to constrain dust attenuation. The SED of each source is fit using the CIGALE code. The amount of dust attenuation and the characteristics of the dust attenuation curve are obtained as outputs of the SED fitting process, together with other physical parameters linked to the star formation history. Results: The global amount of dust attenuation at UV wavelengths is found to increase with stellar mass and to decrease as UV luminosity increases. A UV bump at 2175 Å is securely detected in 20% of the galaxies, and the mean amplitude of the bump for the sample is similar to that observed in the extinction curve of the LMC supershell region. This amplitude is found to be lower in galaxies with very high specific star formation rates, and 90% of the galaxies exhibiting a secure bump are at z < 1.5. The attenuation curve is confirmed to be steeper than that of local starburst galaxies for 20% of the galaxies. The large dispersion found for these two parameters describing the attenuation law is likely to reflect a wide diversity of attenuation laws among galaxies. The relations between dust attenuation, IR-to-UV flux ratio, and the slope of the UV continuum are derived for the mean attenuation curve found for our sample. Deviations from the average trends are found to correlate with the age of the young stellar population and the shape of the attenuation curve. Table of multi-colour photometry for the 751 galaxies is only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/545/A141

Explosive bonding of metal-matrix composites

NASA Technical Reports Server (NTRS)

Reece, O. Y.

1969-01-01

Explosive bonding process produces sheet composites of aluminum alloy reinforced by high-strength stainless steel wires. The bonds are excellent metallurgically, no external heat is required, various metals can be bonded, and the process is inexpensive.

Weld bonding of titanium with polyimide adhesives

NASA Technical Reports Server (NTRS)

Vaughan, R. W.; Sheppard, C. H.; Orell, M. K.

1975-01-01

A conductive adhesive primer and a capillary flow adhesive were developed for weld bonding titanium alloy joints. Both formulations contained ingredients considered to be non-carcinogenic. Lap-shear joint test specimens and stringer-stiffened panels were weld bonded using a capillary flow process to apply the adhesive. Static property information was generated for weld bonded joints over the temperature range of 219K (-65 F) to 561K (550 F). The capillary flow process was demonstrated to produce weld bonded joints of equal strength to the weld through weld bonding process developed previously.

A Novel Process for Joining Ti Alloy and Al Alloy using Two-Stage Sintering Powder Metallurgy

NASA Astrophysics Data System (ADS)

Long, Luping; Liu, Wensheng; Ma, Yunzhu; Wu, Lei; Liu, Chao

2018-04-01

The major challenges for conventional diffusion bonding of joining Ti alloy and Al alloy are the undesirable interfacial reaction, low matrixes and joint strength. To avoid the problem in diffusion bonding, a novel two-stage sintering powder metallurgy process is developed. In the present work, the interface characterization and joint performance of the bonds obtained by powder metallurgy bonding are investigated and are compared with the diffusion bonded Ti/Al joints obtained with the same and the optimized process parameters. The results show that no intermetallic compound is visible in the Ti/Al joint obtained by powder metallurgy bonding, while a new layer formed at the joint diffusion bonded with the same parameters. The maximum tensile strength of joint obtained by diffusion bonding is 58 MPa, while a higher tensile strength reaching 111 MPa for a bond made by powder metallurgy bonding. Brittle fractures occur at all the bonds. It is shown that the powder metallurgy bonding of Ti/Al is better than diffusion bonding. The results of this study should benefit the bonding quality.

Vacuum pull down method for an enhanced bonding process

DOEpatents

Davidson, James C.; Balch, Joseph W.

1999-01-01

A process for effectively bonding arbitrary size or shape substrates. The process incorporates vacuum pull down techniques to ensure uniform surface contact during the bonding process. The essence of the process for bonding substrates, such as glass, plastic, or alloys, etc., which have a moderate melting point with a gradual softening point curve, involves the application of an active vacuum source to evacuate interstices between the substrates while at the same time providing a positive force to hold the parts to be bonded in contact. This enables increasing the temperature of the bonding process to ensure that the softening point has been reached and small void areas are filled and come in contact with the opposing substrate. The process is most effective where at least one of the two plates or substrates contain channels or grooves that can be used to apply vacuum between the plates or substrates during the thermal bonding cycle. Also, it is beneficial to provide a vacuum groove or channel near the perimeter of the plates or substrates to ensure bonding of the perimeter of the plates or substrates and reduce the unbonded regions inside the interior region of the plates or substrates.

Unified, flavor symmetric explanation for the tt asymmetry and Wjj excess at CDF

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

Nelson, Ann E.; Roy, Tuhin S.; Okui, Takemichi

2011-11-01

We present a simple, perturbative, and renormalizable model with a flavor symmetry which can explain both the tt forward-backward asymmetry and the bump feature present in the dijet mass distribution of the W+jj sample in the range 120-160 GeV that was recently reported by the CDF collaboration. The flavor symmetry not only ensures the flavor/CP safety of the model, but also relates the two anomalies unambiguously. It predicts a comparable forward-backward asymmetry in cc. The forward-backward asymmetry in bb is, however, small. A bump in the dijet mass distribution in Z+jj sample is also predicted but with a suppressed crossmore » section.« less

Ultra-low roughness magneto-rheological finishing for EUV mask substrates

NASA Astrophysics Data System (ADS)

Dumas, Paul; Jenkins, Richard; McFee, Chuck; Kadaksham, Arun J.; Balachandran, Dave K.; Teki, Ranganath

2013-09-01

EUV mask substrates, made of titania-doped fused silica, ideally require sub-Angstrom surface roughness, sub-30 nm flatness, and no bumps/pits larger than 1 nm in height/depth. To achieve the above specifications, substrates must undergo iterative global and local polishing processes. Magnetorheological finishing (MRF) is a local polishing technique which can accurately and deterministically correct substrate figure, but typically results in a higher surface roughness than the current requirements for EUV substrates. We describe a new super-fine MRF® polishing fluid whichis able to meet both flatness and roughness specifications for EUV mask blanks. This eases the burden on the subsequent global polishing process by decreasing the polishing time, and hence the defectivity and extent of figure distortion.

Spectral CT data acquisition with Medipix3.1

NASA Astrophysics Data System (ADS)

Walsh, M. F.; Nik, S. J.; Procz, S.; Pichotka, M.; Bell, S. T.; Bateman, C. J.; Doesburg, R. M. N.; De Ruiter, N.; Chernoglazov, A. I.; Panta, R. K.; Butler, A. P. H.; Butler, P. H.

2013-10-01

This paper describes the acquisition of spectral CT images using the Medipix3.1 in spectroscopic mode, in which the chip combines 2 × 2 pixel clusters to increase the number of energy thresholds and counters from 2 to 8. During preliminary measurements, it was observed that the temperature, DAC and equalisation stability of the Medipix3.1 outperformed the Medipix3.0, while maintaining similar imaging quality. In this paper, the Medipix3.1 chips were assembled in a quad (2 × 2) layout, with the four ASICs bump-bonded to a silicon semiconductor doped as an np-junction diode. To demonstrate the biological imaging quality that is possible with the Medipix3.1, an image of a mouse injected with gold nano-particle contrast agent was obtained. CT acquisition in spectroscopic mode was enabled and examined by imaging a customised phantom containing multiple contrast agents and biological materials. These acquisitions showed a limitation of imaging performance depending on the counter used. Despite this, identification of multiple materials in the phantom was demonstrated using an in-house material decomposition algorithm. Furthermore, gold nano-particles were separated from biological tissues and bones within the mouse by means of image rendering.

New leads for selective GSK-3 inhibition: pharmacophore mapping and virtual screening studies.

PubMed

Patel, Dhilon S; Bharatam, Prasad V

2006-01-01

Glycogen Synthase Kinase-3 is a regulatory serine/threonine kinase, which is being targeted for the treatment of a number of human diseases including type-2 diabetes mellitus, neurodegenerative diseases, cancer and chronic inflammation. Selective GSK-3 inhibition is an important requirement owing to the possibility of side effects arising from other kinases. A pharmacophore mapping strategy is employed in this work to identify new leads for selective GSK-3 inhibition. Ligands known to show selective GSK-3 inhibition were employed in generating a pharmacophore map using distance comparison method (DISCO). The derived pharmacophore map was validated using (i) important interactions involved in selective GSK-3 inhibitions, and (ii) an in-house database containing different classes of GSK-3 selective, non-selective and inactive molecules. New Lead identification was carried out by performing virtual screening using validated pharmacophoric query and three chemical databases namely NCI, Maybridge and Leadquest. Further data reduction was carried out by employing virtual filters based on (i) Lipinski's rule of 5 (ii) van der Waals bumps and (iii) restricting the number of rotatable bonds to seven. Final screening was carried out using FlexX based molecular docking study.

New leads for selective GSK-3 inhibition: pharmacophore mapping and virtual screening studies

NASA Astrophysics Data System (ADS)

Patel, Dhilon S.; Bharatam, Prasad V.

2006-01-01

Glycogen Synthase Kinase-3 is a regulatory serine/threonine kinase, which is being targeted for the treatment of a number of human diseases including type-2 diabetes mellitus, neurodegenerative diseases, cancer and chronic inflammation. Selective GSK-3 inhibition is an important requirement owing to the possibility of side effects arising from other kinases. A pharmacophore mapping strategy is employed in this work to identify new leads for selective GSK-3 inhibition. Ligands known to show selective GSK-3 inhibition were employed in generating a pharmacophore map using distance comparison method (DISCO). The derived pharmacophore map was validated using (i) important interactions involved in selective GSK-3 inhibitions, and (ii) an in-house database containing different classes of GSK-3 selective, non-selective and inactive molecules. New Lead identification was carried out by performing virtual screening using validated pharmacophoric query and three chemical databases namely NCI, Maybridge and Leadquest. Further data reduction was carried out by employing virtual filters based on (i) Lipinski's rule of 5 (ii) van der Waals bumps and (iii) restricting the number of rotatable bonds to seven. Final screening was carried out using FlexX based molecular docking study.

Design methodology: edgeless 3D ASICs with complex in-pixel processing for pixel detectors

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

Fahim Farah, Fahim Farah; Deptuch, Grzegorz W.; Hoff, James R.

The design methodology for the development of 3D integrated edgeless pixel detectors with in-pixel processing using Electronic Design Automation (EDA) tools is presented. A large area 3 tier 3D detector with one sensor layer and two ASIC layers containing one analog and one digital tier, is built for x-ray photon time of arrival measurement and imaging. A full custom analog pixel is 65μm x 65μm. It is connected to a sensor pixel of the same size on one side, and on the other side it has approximately 40 connections to the digital pixel. A 32 x 32 edgeless array withoutmore » any peripheral functional blocks constitutes a sub-chip. The sub-chip is an indivisible unit, which is further arranged in a 6 x 6 array to create the entire 1.248cm x 1.248cm ASIC. Each chip has 720 bump-bond I/O connections, on the back of the digital tier to the ceramic PCB. All the analog tier power and biasing is conveyed through the digital tier from the PCB. The assembly has no peripheral functional blocks, and hence the active area extends to the edge of the detector. This was achieved by using a few flavors of almost identical analog pixels (minimal variation in layout) to allow for peripheral biasing blocks to be placed within pixels. The 1024 pixels within a digital sub-chip array have a variety of full custom, semi-custom and automated timing driven functional blocks placed together. The methodology uses a modified mixed-mode on-top digital implementation flow to not only harness the tool efficiency for timing and floor-planning but also to maintain designer control over compact parasitically aware layout. The methodology uses the Cadence design platform, however it is not limited to this tool.« less

A fast embedded readout system for large-area Medipix and Timepix systems

NASA Astrophysics Data System (ADS)

Brogna, A. S.; Balzer, M.; Smale, S.; Hartmann, J.; Bormann, D.; Hamann, E.; Cecilia, A.; Zuber, M.; Koenig, T.; Zwerger, A.; Weber, M.; Fiederle, M.; Baumbach, T.

2014-05-01

In this work we present a novel readout electronics for an X-ray sensor based on a Si crystal bump-bonded to an array of 3 × 2 Medipix ASICs. The pixel size is 55 μm × 55 μm with a total number of ~ 400k pixels and a sensitive area of 42 mm × 28 mm. The readout electronics operate Medipix-2 MXR or Timepix ASICs with a clock speed of 125 MHz. The data acquisition system is centered around an FPGA and each of the six ASICs has a dedicated I/O port for simultaneous data acquisition. The settings of the auxiliary devices (ADCs and DACs) are also processed in the FPGA. Moreover, a high-resolution timer operates the electronic shutter to select the exposure time from 8 ns to several milliseconds. A sophisticated trigger is available in hardware and software to synchronize the acquisition with external electro-mechanical motors. The system includes a diagnostic subsystem to check the sensor temperature and to control the cooling Peltier cells and a programmable high-voltage generator to bias the crystal. A network cable transfers the data, encapsulated into the UDP protocol and streamed at 1 Gb/s. Therefore most notebooks or personal computers are able to process the data and to program the system without a dedicated interface. The data readout software is compatible with the well-known Pixelman 2.x running both on Windows and GNU/Linux. Furthermore the open architecture encourages users to write their own applications. With a low-level interface library which implements all the basic features, a MATLAB or Python script can be implemented for special manipulations of the raw data. In this paper we present selected images taken with a microfocus X-ray tube to demonstrate the capability to collect the data at rates up to 120 fps corresponding to 0.76 Gb/s.

Design methodology: edgeless 3D ASICs with complex in-pixel processing for pixel detectors

NASA Astrophysics Data System (ADS)

Fahim, Farah; Deptuch, Grzegorz W.; Hoff, James R.; Mohseni, Hooman

2015-08-01

The design methodology for the development of 3D integrated edgeless pixel detectors with in-pixel processing using Electronic Design Automation (EDA) tools is presented. A large area 3 tier 3D detector with one sensor layer and two ASIC layers containing one analog and one digital tier, is built for x-ray photon time of arrival measurement and imaging. A full custom analog pixel is 65μm x 65μm. It is connected to a sensor pixel of the same size on one side, and on the other side it has approximately 40 connections to the digital pixel. A 32 x 32 edgeless array without any peripheral functional blocks constitutes a sub-chip. The sub-chip is an indivisible unit, which is further arranged in a 6 x 6 array to create the entire 1.248cm x 1.248cm ASIC. Each chip has 720 bump-bond I/O connections, on the back of the digital tier to the ceramic PCB. All the analog tier power and biasing is conveyed through the digital tier from the PCB. The assembly has no peripheral functional blocks, and hence the active area extends to the edge of the detector. This was achieved by using a few flavors of almost identical analog pixels (minimal variation in layout) to allow for peripheral biasing blocks to be placed within pixels. The 1024 pixels within a digital sub-chip array have a variety of full custom, semi-custom and automated timing driven functional blocks placed together. The methodology uses a modified mixed-mode on-top digital implementation flow to not only harness the tool efficiency for timing and floor-planning but also to maintain designer control over compact parasitically aware layout. The methodology uses the Cadence design platform, however it is not limited to this tool.

Bumpy light curves of interacting supernovae

NASA Astrophysics Data System (ADS)

Nyholm, Anders

2017-04-01

A supernova (SN) is the explosive destruction of a star. Via a luminous outpouring of radiation, the SN can rival the brightness of its SN host galaxy for months or years. In the past decade, astronomical surveys regularly observing the sky to deep limiting magnitudes have revealed that core collapse SNe (the demises of massive stars) are sometimes preceded by eruptive episodes by the progenitor stars during the years before the eventual SN explosion. Such SNe tend to show strong signatures of interaction between the SN ejecta and the circumstellar medium (CSM) deposited by the star before the SN explosion, likely by mass-loss episodes like the ones we have started to observe regularly. The complex CSM resolved around certain giant stars in our own galaxy and the eruptions of giant stars like Eta Carinae in the 19th century can be seen in this context. As the SN ejecta of an interacting SN sweep up the CSM of the progenitor, radiation from this process offers observers opportunity to scan the late mass loss history of the progenitor. In this thesis, interacting SNe and eruptive mass loss of their progenitors is discussed. The SN iPTF13z (discovered by the intermediate Palomar Transient Factory, iPTF) is presented. This transient was followed with optical photometry and spectroscopy during 1000 days and displayed a light curve with several conspicuous re-brigthenings ("bumps"), likely arising from SN ejecta interacting with denser regions in the CSM. Around 200 days before discovery, in archival data we found a clear precursor outburst lasting ∼50 days. A well-observed (but not necessarily well understood) event like SN 2009ip, which showed both precursor outbursts and a light curve bump, makes an interesting comparison object. The embedding of the (possible) SN in a CSM makes it hard to tell if a destructive SN explosion actually happened. In this respect, iPTF13z is compared to e.g. SN 2009ip but also to long-lived interacting SNe like SN 1988Z. Some suggestions for future investigations are offered, to tie light curve bumps to precursor events and to clarify the question of core collapse in the ambiguous cases of some interacting SNe.

Miniaturization of Micro-Solder Bumps and Effect of IMC on Stress Distribution

NASA Astrophysics Data System (ADS)

Choudhury, Soud Farhan; Ladani, Leila

2016-07-01

As the joints become smaller in more advanced packages and devices, intermetallic (IMCs) volume ratio increases, which significantly impacts the overall mechanical behavior of joints. The existence of only a few grains of Sn (Tin) and IMC materials results in anisotropic elastic and plastic behavior which is not detectable using conventional finite element (FE) simulation with average properties for polycrystalline material. In this study, crystal plasticity finite element (CPFE) simulation is used to model the whole joint including copper, Sn solder and Cu6Sn5 IMC material. Experimental lap-shear test results for solder joints from the literature were used to validate the models. A comparative analysis between traditional FE, CPFE and experiments was conducted. The CPFE model was able to correlate the experiments more closely compared to traditional FE analysis because of its ability to capture micro-mechanical anisotropic behavior. Further analysis was conducted to evaluate the effect of IMC thickness on stress distribution in micro-bumps using a systematic numerical experiment with IMC thickness ranging from 0% to 80%. The analysis was conducted on micro-bumps with single crystal Sn and bicrystal Sn. The overall stress distribution and shear deformation changes as the IMC thickness increases. The model with higher IMC thickness shows a stiffer shear response, and provides a higher shear yield strength.

Condensation on Slippery Asymmetric Bumps

NASA Astrophysics Data System (ADS)

Park, Kyoo-Chul; Kim, Philseok; Aizenberg, Joanna

Controlling dropwise condensation by designing surfaces that enable droplets to grow rapidly and be shed as quickly as possible is fundamental to water harvesting systems, thermal power generation, distillation towers, etc. However, cutting-edge approaches based on micro/nanoscale textures suffer from intrinsic trade-offs that make it difficult to optimize both growth and transport at once. Here we present a conceptually different design approach based on principles derived from Namib desert beetles, cacti, and pitcher plants that synergistically couples both aspects of condensation and outperforms other synthetic surfaces. Inspired by an unconventional interpretation of the role of the beetle's bump geometry in promoting condensation, we show how to maximize vapor diffusion flux at the apex of convex millimetric bumps by optimizing curvature and shape. Integrating this apex geometry with a widening slope analogous to cactus spines couples rapid drop growth with fast directional transport, by creating a free energy profile that drives the drop down the slope. This coupling is further enhanced by a slippery, pitcher plant-inspired coating that facilitates feedback between coalescence-driven growth and capillary-driven motion. We further observe an unprecedented six-fold higher exponent in growth rate and much faster shedding time compared to other surfaces. We envision that our fundamental understanding and rational design strategy can be applied to a wide range of phase change applications.

Condensation on Slippery Asymmetric Bumps

NASA Astrophysics Data System (ADS)

Park, Kyoo-Chul; Kim, Philseok; Aizenberg, Joanna

2016-11-01

Controlling dropwise condensation by designing surfaces that enable droplets to grow rapidly and be shed as quickly as possible is fundamental to water harvesting systems, thermal power generation, distillation towers, etc. However, cutting-edge approaches based on micro/nanoscale textures suffer from intrinsic trade-offs that make it difficult to optimize both growth and transport at once. Here we present a conceptually different design approach based on principles derived from Namib desert beetles, cacti, and pitcher plants that synergistically couples both aspects of condensation and outperforms other synthetic surfaces. Inspired by an unconventional interpretation of the role of the beetle's bump geometry in promoting condensation, we show how to maximize vapor diffusion flux at the apex of convex millimetric bumps by optimizing curvature and shape. Integrating this apex geometry with a widening slope analogous to cactus spines couples rapid drop growth with fast directional transport, by creating a free energy profile that drives the drop down the slope. This coupling is further enhanced by a slippery, pitcher plant-inspired coating that facilitates feedback between coalescence-driven growth and capillary-driven motion. We further observe an unprecedented six-fold higher exponent in growth rate and much faster shedding time compared to other surfaces. We envision that our fundamental understanding and rational design strategy can be applied to a wide range of phase change applications.

Distributions of p-values smaller than .05 in psychology: what is going on?

PubMed Central

van Aert, Robbie C.M.; Nuijten, Michèle B.; Wicherts, Jelte M.; van Assen, Marcel A.L.M.

2016-01-01

Previous studies provided mixed findings on pecularities in p-value distributions in psychology. This paper examined 258,050 test results across 30,710 articles from eight high impact journals to investigate the existence of a peculiar prevalence of p-values just below .05 (i.e., a bump) in the psychological literature, and a potential increase thereof over time. We indeed found evidence for a bump just below .05 in the distribution of exactly reported p-values in the journals Developmental Psychology, Journal of Applied Psychology, and Journal of Personality and Social Psychology, but the bump did not increase over the years and disappeared when using recalculated p-values. We found clear and direct evidence for the QRP “incorrect rounding of p-value” (John, Loewenstein & Prelec, 2012) in all psychology journals. Finally, we also investigated monotonic excess of p-values, an effect of certain QRPs that has been neglected in previous research, and developed two measures to detect this by modeling the distributions of statistically significant p-values. Using simulations and applying the two measures to the retrieved test results, we argue that, although one of the measures suggests the use of QRPs in psychology, it is difficult to draw general conclusions concerning QRPs based on modeling of p-value distributions. PMID:27077017

Interfacial reactions and compound formation of Sn-Ag-Cu solders by mechanical alloying on electroless Ni-P/Cu under bump metallization

NASA Astrophysics Data System (ADS)

Kao, Szu-Tsung; Duh, Jenq-Gong

2005-08-01

Electroless Ni-P under bump metallization (UBM) has been widely used in electronic interconnections due to the good diffusion barrier between Cu and solder. In this study, the mechanical alloying (MA) process was applied to produce the SnAgCu lead-free solder pastes. Solder joints after annealing at 240°C for 15 min were employed to investigate the evolution of interfacial reaction between electroless Ni-P/Cu UBM and SnAgCu solder with various Cu concentrations ranging from 0.2 to 1.0 wt.%. After detailed quantitative analysis with an electron probe microanalyzer, the effect of Cu content on the formation of intermetallic compounds (IMCs) at SnAgCu solder/electroless Ni-P interface was evaluated. When the Cu concentration in the solder was 0.2 wt.%, only one (Ni, Cu)3Sn4 layer was observed at the solder/electroless Ni-P interface. As the Cu content increased to 0.5 wt.%, (Cu, Ni)6Sn5 formed along with (Ni, Cu)3Sn4. However, only one (Cu, Ni)6Sn5 layer was revealed, if the Cu content was up to 1 wt.%. With the aid of microstructure evolution, quantitative analysis, and elemental distribution by x-ray color mapping, the presence of the Ni-Sn-P phase and P-rich layer was evidenced.

Precision Photometry of Long Period Variable Stars: Flares and Bumps in the Night (Poster abstract)

NASA Astrophysics Data System (ADS)

Mais, D.

2015-06-01

(Abstract only) Mira variable stars are a broad class of stars, which encompass spectroscopic classes of type M, S, and C. These stars are closely related in terms of their long term variability, position on the Hertzsprung-Russell diagram their intermediate mass (from ~0.8 to ~8 solar mass) and the fact that class M evolves into the S and C type stars as certain stages of shell burning around the core proceeds. Recently, evidence has accumulated to suggest that Mira variables may go through flare up stages which result in brightening on the order of several tenths of a magnitude or more and may last hours to days in length. Very little is known about these events, indeed it is not clear that these events are real. In order to address the reality of these events, we established an automated acquisition/analysis of a group of 108 Mira variables in order to obtain the densest coverage of the periods to better constrain the potential flare-ups. Telescope control scripts were put in place along with real time analysis. This allowed for unattended acquisition of data on every clear night, all night long, in the V, R, and I photometric bands. In addition, during the course of the night multiple determinations are often obtained for a given star. The light curves of many of the program stars show a Cepheid-like bump phenomenon, however these appear on the ascending part of the light curve. In general, these bumps appear in longer period Mira's (>350 days). Bumps are not obvious or easily seen in VISUAL data records, although slope changes during rising phase are seen in some cases. So far, greater than 100,000 magnitude determinations have been obtained, many closely spaced in time. This should help to further constrain the potential occurrences of flare-up events.

Dust in the small Magellanic cloud. 1: Interstellar polarization and extinction data

NASA Technical Reports Server (NTRS)

Magalhaes, A. M.; Rodrigues, C. V.; Coyne, C. V.; Piirola, V.

1996-01-01

The typical extinction curve for the Small Magellanic Cloud (SMC), in contrast to that for the Galaxy, has no bump at 2175 A and has a steeper rise into the far ultraviolet. For the Galaxy the interpretation of the extinction and, therefore, the dust content of the interstellar medium has been greatly assisted by measurements of the wavelength dependence of the polarization. For the SMC no such measurements existed. Therefore, to further elucidate the dust properties in the SMC we have for the first time measured linear polarization with five colors in the optical region of the spectrum for a sample of reddened stars. For two of these stars, for which there were no existing UV spectrophotometric measurements, but for which we measured a relatively large polarization, we have also obtained data from the International Ultraviolet Explorer (IUE) in order to study the extinction. We also attempt to correlate the SMC extinction and polarization data. The main results are: the wavelength of maximum polarization, lambda(sub max), in the SMC is typically smaller than that in the Galaxy; however, AZC 456, which shows the UV extinction bump, has a lambda(sub max) typical of that in the Galaxy, but its polarization curve is narrower and its bump is shifted to shorter wavelengths as compared to the Galaxy; and from an analysis of both the extinction and polarization data it appears that the SMC has typically smaller grains than those in the Galaxy. The absence of the extinction bump in the SMC has generally been thought to imply a lower carbon abundance in the SMC compared to the Galaxy. We interpret our results to mean that te size distribution of the interstellar grains, and not only the carbon abundance, is different in the SMC as compared to the Galaxy. In Paper 2 we present dust model fits to these observations.

HUBBLE SPACE TELESCOPE MORPHOLOGIES OF z {approx} 2 DUST-OBSCURED GALAXIES. II. BUMP SOURCES

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

Bussmann, R. S.; Dey, Arjun; Lotz, J.

We present Hubble Space Telescope imaging of 22 ultra-luminous infrared galaxies (ULIRGs) at z {approx} 2 with extremely red R - [24] colors (called dust-obscured galaxies, or DOGs) which have a local maximum in their spectral energy distribution (SED) at rest-frame 1.6 {mu}m associated with stellar emission. These sources, which we call 'bump DOGs', have star formation rates (SFRs) of 400-4000 M{sub sun} yr{sup -1} and have redshifts derived from mid-IR spectra which show strong polycyclic aromatic hydrocarbon emission-a sign of vigorous ongoing star formation. Using a uniform morphological analysis, we look for quantifiable differences between bump DOGs, power-law DOGsmore » (Spitzer-selected ULIRGs with mid-IR SEDs dominated by a power law and spectral features that are more typical of obscured active galactic nuclei than starbursts), submillimeter-selected galaxies, and other less-reddened ULIRGs from the Spitzer Extragalactic First Look Survey. Bump DOGs are larger than power-law DOGs (median Petrosian radius of 8.4 {+-} 2.7 kpc versus 5.5 {+-} 2.3 kpc) and exhibit more diffuse and irregular morphologies (median M{sub 20} of -1.08 {+-} 0.05 versus -1.48 {+-} 0.05). These trends are qualitatively consistent with expectations from simulations of major mergers in which merging systems during the peak SFR period evolve from M{sub 20} = -1.0 to M{sub 20} = -1.7. Less-obscured ULIRGs (i.e., non-DOGs) tend to have more regular, centrally peaked, single-object morphologies rather than diffuse and irregular morphologies. This distinction in morphologies may imply that less-obscured ULIRGs sample the merger near the end of the peak SFR period. Alternatively, it may indicate that the intense star formation in these less-obscured ULIRGs is not the result of a recent major merger.« less

Deep Photometry of GRB 041006 Afterglow: Hypernova Bump at Redshift z = 0.716

NASA Astrophysics Data System (ADS)

Stanek, K. Z.; Garnavich, P. M.; Nutzman, P. A.; Hartman, J. D.; Garg, A.; Adelberger, K.; Berlind, P.; Bonanos, A. Z.; Calkins, M. L.; Challis, P.; Gaudi, B. S.; Holman, M. J.; Kirshner, R. P.; McLeod, B. A.; Osip, D.; Pimenova, T.; Reiprich, T. H.; Romanishin, W.; Spahr, T.; Tegler, S. C.; Zhao, X.

2005-06-01

We present deep optical photometry of the afterglow of gamma-ray burst (GRB) 041006 and its associated hypernova obtained over 65 days after detection (55 R-band epochs on 10 different nights). Our early data (t<4 days) joined with published GCN data indicate a steepening decay, approaching Fν~t-0.6 at early times (t<<1 day) and Fν~t-1.3 at late times. The break at tb=0.16+/-0.04 days is the earliest reported jet break among all GRB afterglows. During our first night, we obtained 39 exposures spanning 2.15 hr from 0.62 to 0.71 days after the burst that reveal a smooth afterglow, with an rms deviation of 0.024 mag from the local power-law fit, consistent with photometric errors. After t~4 days, the decay slows considerably, and the light curve remains approximately flat at R~24 mag for a month before decaying by another magnitude to reach R~25 mag 2 months after the burst. This ``bump'' is well fit by a k-corrected light curve of supernova SN 1998bw, but only if stretched by a factor of 1.38 in time. In comparison with the other GRB-related SN bumps, GRB 041006 stakes out new parameter space for GRBs/SNe, with a very bright and significantly stretched late-time SN light curve. Within a small sample of fairly well observed GRB/SN bumps, we see a hint of a possible correlation between their peak luminosity and their ``stretch factor,'' broadly similar to the well-studied Phillips relation for the Type Ia supernovae. Based on data from the MMT Observatory 6.5 m telescope, the 1.8 m Vatican Advanced Technology Telescope, the Magellan 6.5 m Baade and Clay telescopes, and the Keck II 10 m telescope.

Cleanliness inspection tool for RSRM bond surfaces

NASA Technical Reports Server (NTRS)

Mattes, Robert A.

1995-01-01

Using optically stimulated electron emission (OSEE), Thiokol has monitored bond surfaces in process for contamination on the Redesigned Solid Rocket Motor (RSRM). This technique provides process control information to help assure bond surface quality and repeatability prior to bonding. This paper will describe OSEE theory of operation and the instrumentation implemented at Thiokol Corporation since 1987. Data from process hardware will be presented.

NASA Tech Briefs, December 2005

NASA Technical Reports Server (NTRS)

2005-01-01

Topics covered include: Video Mosaicking for Inspection of Gas Pipelines; Shuttle-Data-Tape XML Translator; Highly Reliable, High-Speed, Unidirectional Serial Data Links; Data-Analysis System for Entry, Descent, and Landing; Hybrid UV Imager Containing Face-Up AlGaN/GaN Photodiodes; Multiple Embedded Processors for Fault-Tolerant Computing; Hybrid Power Management; Magnetometer Based on Optoelectronic Microwave Oscillator; Program Predicts Time Courses of Human/ Computer Interactions; Chimera Grid Tools; Astronomer's Proposal Tool; Conservative Patch Algorithm and Mesh Sequencing for PAB3D; Fitting Nonlinear Curves by Use of Optimization Techniques; Tool for Viewing Faults Under Terrain; Automated Synthesis of Long Communication Delays for Testing; Solving Nonlinear Euler Equations With Arbitrary Accuracy; Self-Organizing-Map Program for Analyzing Multivariate Data; Tool for Sizing Analysis of the Advanced Life Support System; Control Software for a High-Performance Telerobot; Java Radar Analysis Tool; Architecture for Verifiable Software; Tool for Ranking Research Options; Enhanced, Partially Redundant Emergency Notification System; Close-Call Action Log Form; Task Description Language; Improved Small-Particle Powders for Plasma Spraying; Bonding-Compatible Corrosion Inhibitor for Rinsing Metals; Wipes, Coatings, and Patches for Detecting Hydrazines; Rotating Vessels for Growing Protein Crystals; Oscillating-Linear-Drive Vacuum Compressor for CO2; Mechanically Biased, Hinged Pairs of Piezoelectric Benders; Apparatus for Precise Indium-Bump Bonding of Microchips; Radiation Dosimetry via Automated Fluorescence Microscopy; Multistage Magnetic Separator of Cells and Proteins; Elastic-Tether Suits for Artificial Gravity and Exercise; Multichannel Brain-Signal-Amplifying and Digitizing System; Ester-Based Electrolytes for Low-Temperature Li-Ion Cells; Hygrometer for Detecting Water in Partially Enclosed Volumes; Radio-Frequency Plasma Cleaning of a Penning Malmberg Trap; Reduction of Flap Side Edge Noise - the Blowing Flap; and Preventing Accidental Ignition of Upper-Stage Rocket Motors.

The bumpy light curve of Type IIn supernova iPTF13z over 3 years

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

Nyholm, A.; Sollerman, J.; Taddia, F.

A core-collapse (CC) supernova (SN) of Type IIn is dominated by the interaction of SN ejecta with the circumstellar medium (CSM). Some SNe IIn (e.g. SN 2006jd) have episodes of re-brightening ("bumps") in their light curves. We present iPTF13z, a Type IIn SN discovered on 2013 February 1 by the intermediate Palomar Transient Factory (iPTF). This SN showed at least five bumps in its declining light curve between 130 and 750 days after discovery. We analyse this peculiar behaviour and try to infer the properties of the CSM, of the SN explosion, and the nature of the progenitor star. Wemore » obtained multi-band optical photometry for over 1000 days after discovery with the P48 and P60 telescopes at Palomar Observatory. We obtained low-resolution optical spectra during the same period. We did an archival search for progenitor outbursts. We analyse the photometry and the spectra, and compare iPTF13z to other SNe IIn. In particular we derive absolute magnitudes, colours, a pseudo-bolometric light curve, and the velocities of the different components of the spectral lines. A simple analytical model is used to estimate the properties of the CSM. iPTF13z had a light curve peaking at M r ≤ 18.3 mag. The five bumps during its decline phase had amplitudes ranging from 0.4 to 0.9 mag and durations between 20 and 120 days. The most prominent bumps appeared in all the different optical bands, when covered. The spectra of this SN showed typical SN IIn characteristics, with emission lines of Hα (with broad component FWHM ~ 10 3 - 10 4 km s -1 and narrow component FWHM ~ 10 2 km s -1 ) and He i, but also with Fe ii, Ca ii, Na i D and Hβ P Cygni profiles (with velocities of ~ 10 3 km s -1). A pre-explosion outburst was identified lasting ≳ 50 days, with M r ≤ 15 mag around 210 days before discovery. Large, variable progenitor mass-loss rates (≳ 0.01M ⊙ yr -1) and CSM densities (10 -16 g cm -3) are derived. The SN was hosted by a metal-poor dwarf galaxy at redshift z = 0.0328. We suggest that the light curve bumps of iPTF13z arose from SN ejecta interacting with denser regions in the CSM, possibly produced by the eruptions of a luminous blue variable progenitor star.« less

Nondestructive insights into composition of the sculpture of Egyptian Queen Nefertiti with CT.

PubMed

Huppertz, Alexander; Wildung, Dietrich; Kemp, Barry J; Nentwig, Tanja; Asbach, Patrick; Rasche, Franz Maximilian; Hamm, Bernd

2009-04-01

To assess the conservation status of, to gain information on the creation of, and to provide surface reformations of the core and the surface of the bust of the pharaoh-queen Nefertiti, considered to be one of the greatest treasures of ancient Egyptian art, with computed tomography (CT). Multisection CT was performed with 0.6-mm section thickness. Two- and three-dimensional reformations were made to depict the core and the surface separately. The stucco layer on the face and the ears was very thin, a maximum of 1-2 mm thick. The rear part of the reconstructed crown showed two thick stucco layers of different attenuation values, indicating that a multistep process was used to create the sculpture. Within the stucco, a great number of air-equivalent hypoattenuating areas, filamentous fissures parallel to the surface, and an inhomogeneous bonding between the layers were delineated. Nefertiti's inner face was not anonymous, but rather delicately sculpted by the royal sculptor Thutmose. The comparison to the outer face revealed differences, including the angles of the eyelids, creases around the corners of the mouth on the limestone surface, and a slight bump on the ridge of the nose. According to the beauty ideals of the Amarna period, the differences had positive and negative effects and can be read as signs of individualization of the sculpture. The potential material-related weaknesses of the sculpture that were revealed at imaging necessitate careful handling, with the avoidance of any focal pressure and shearing forces in the crown and the shoulders. CT imaging revealed construction techniques in Nefertiti's bust that had implications for conservation, as well as for an understanding of the artistic methods used in the creation of this masterpiece of art of the 18th dynasty.

Rapid adhesive bonding of advanced composites and titanium

NASA Technical Reports Server (NTRS)

Stein, B. A.; Tyeryart, J. R.; Hodgest, W. T.

1985-01-01

Rapid adhesive bonding (RAB) concepts utilize a toroid induction technique to heat the adhesive bond line directly. This technique was used to bond titanium overlap shear specimens with 3 advanced thermoplastic adhesives and APC-2 (graphite/PEEK) composites with PEEK film. Bond strengths equivalent to standard heated-platen press bonds were produced with large reductions in process time. RAB produced very strong bonds in APC-2 adherend specimens; the APC-2 adherends were highly resistant to delamination. Thermal cycling did not significantly affect the shear strengths of RAB titanium bonds with polyimide adhesives. A simple ultrasonic non-destructive evaluation process was found promising for evaluating bond quality.

STRUCTURAL GLITCHES NEAR THE CORES OF RED GIANTS REVEALED BY OSCILLATIONS IN G-MODE PERIOD SPACINGS FROM STELLAR MODELS

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

Cunha, M. S.; Avelino, P. P.; Stello, D.

2015-06-01

With recent advances in asteroseismology it is now possible to peer into the cores of red giants, potentially providing a way to study processes such as nuclear burning and mixing through their imprint as sharp structural variations—glitches—in the stellar cores. Here we show how such core glitches can affect the oscillations we observe in red giants. We derive an analytical expression describing the expected frequency pattern in the presence of a glitch. This formulation also accounts for the coupling between acoustic and gravity waves. From an extensive set of canonical stellar models we find glitch-induced variation in the period spacingmore » and inertia of non-radial modes during several phases of red giant evolution. Significant changes are seen in the appearance of mode amplitude and frequency patterns in asteroseismic diagrams such as the power spectrum and the échelle diagram. Interestingly, along the red giant branch glitch-induced variation occurs only at the luminosity bump, potentially providing a direct seismic indicator of stars in that particular evolution stage. Similarly, we find the variation at only certain post-helium-ignition evolution stages, namely, in the early phases of helium core burning and at the beginning of helium shell burning, signifying the asymptotic giant branch bump. Based on our results, we note that assuming stars to be glitch-free, while they are not, can result in an incorrect estimate of the period spacing. We further note that including diffusion and mixing beyond classical Schwarzschild could affect the characteristics of the glitches, potentially providing a way to study these physical processes.« less

Verification of the modified model of drying process of a polymer liquid film on a flat substrate by experiment (3) - using organic solvent

NASA Astrophysics Data System (ADS)

Kagami, Hiroyuki

2007-05-01

We have proposed and modified a model of drying process of polymer solution coated on a flat substrate for flat polymer film fabrication and have presented the fruits through Photomask Japan 2002, 2003, 2004, Smart Materials, Nano-, and Micro-Smart Systems 2006 and so on. And for example numerical simulation of the model qualitatively reappears a typical thickness profile of the polymer film formed after drying, that is, the profile that the edge of the film is thicker and just the region next to the edge's bump is thinner. Then we have clarified dependence of distribution of polymer molecules on a flat substrate on a various parameters based on analysis of many numerical simulations. Then we did a few kinds of experiments so as to verify the modified model and reported the results of them through Photomask Japan 2005 and 2006. We could observe some results supporting the modified model. But we could not observe a characteristic region of a valley next to the edge's bump of a polymer film after drying. After some trial of various improved experiments we reached the conclusion that the characteristic region didn't appear by reason that water which vaporized slower than organic solvent was used as solvent. Then, in this study, we adopted organic solvent instead of water as solvent for experiments. As a result, that the characteristic region as mentioned above could be seen and we could verify the model more accurately. In this paper, we present verification of the model through above improved experiments for verification using organic solvent.

Cross-dehydrogenative coupling and oxidative-amination reactions of ethers and alcohols with aromatics and heteroaromatics

PubMed Central

Vuram, Prasanna K.

2017-01-01

Cross-dehydrogenative coupling (CDC) is a process in which, typically, a C–C bond is formed at the expense of two C–H bonds, either catalyzed by metals or other organic compounds, or via uncatalyzed processes. In this perspective, we present various modes of C–H bond-activation at sp3 centers adjacent to ether oxygen atoms, followed by C–C bond formation with aromatic systems as well as with heteroaromatic systems. C–N bond-formation with NH-containing heteroaromatics, leading to hemiaminal ethers, is also an event that can occur analogously to C–C bond formation, but at the expense of C–H and N–H bonds. A large variety of hemiaminal ether-forming reactions have recently appeared in the literature and this perspective also includes this complementary chemistry. In addition, the participation of C–H bonds in alcohols in such processes is also described. Facile access to a wide range of compounds can be attained through these processes, rendering such reactions useful for synthetic applications via Csp3 bond activations. PMID:28970941

Exhibition of veiled features in diffusion bonding of titanium alloy and stainless steel via copper

NASA Astrophysics Data System (ADS)

Thirunavukarasu, Gopinath; Kundu, Sukumar; Laha, Tapas; Roy, Deb; Chatterjee, Subrata

2017-11-01

An investigation was carried out to know the extent of influence of bonding-time on the interface structure and mechanical properties of diffusion bonding (DB) of TiA|Cu|SS. DB of Ti6Al4V (TiA) and 304 stainless steel (SS) using pure copper (Cu) of 200-μm thickness were processed in vacuum using 4-MPa bonding-pressure at 1123 K from 15 to 120 min in steps of 15 min. Preparation of DB was not possible when bonding-time was less than 60 min as the bonding at Cu|SS interface was unsuccessful in spite of effective bonding at TiA|Cu interface; however, successful DB were produced when the bonding-time was 60 min and beyond. DB processed for 60 and 75 min (classified as shorter bonding-time interval) showed distinctive characteristics (structural, mechanical, and fractural) as compared to the DB processed for 90, 105, and 120 min (classified as longer bonding-time interval). DB processed for 60 and 75 min exhibited layer-wise Cu-Ti-based intermetallics at TiA|Cu interface, whereas Cu|SS interface was completely free from reaction products. The layer-wise structure of Cu-Ti-based intermetallics were not observed at TiA|Cu interface in the DB processed for longer bonding-time; however, the Cu|SS interface had layer-wise ternary intermetallic compounds (T1, T2, and T3) of Cu-Fe-Ti-based along with σ phase depending upon the bonding-time chosen. Diffusivity of Ti-atoms in Cu-layer (DTi in Cu-layer) was much greater than the diffusivity of Fe-atoms in Cu-layer (DFe in Cu-layer). Ti-atoms reached Cu|SS interface but Fe-atoms were unable to reach TiA|Cu interface. It was observed that DB fractured at Cu|SS interface when processed for shorter bonding-time interval, whereas the DB processed for longer bonding-time interval fractured apparently at the middle of Cu-foil region predominantly due to the existence of brittle Cu-Fe-Ti-based intermetallics.

Mechanism of bonding and debonding using surface activated bonding method with Si intermediate layer

NASA Astrophysics Data System (ADS)

Takeuchi, Kai; Fujino, Masahisa; Matsumoto, Yoshiie; Suga, Tadatomo

2018-04-01

Techniques of handling thin and fragile substrates in a high-temperature process are highly required for the fabrication of semiconductor devices including thin film transistors (TFTs). In our previous study, we proposed applying the surface activated bonding (SAB) method using Si intermediate layers to the bonding and debonding of glass substrates. The SAB method has successfully bonded glass substrates at room temperature, and the substrates have been debonded after heating at 450 °C, in which TFTs are fabricated on thin glass substrates for LC display devices. In this study, we conducted the bonding and debonding of Si and glass in order to understand the mechanism in the proposed process. Si substrates are also successfully bonded to glass substrates at room temperature and debonded after heating at 450 °C using the proposed bonding process. By the composition analysis of bonding interfaces, it is clarified that the absorbed water on the glass forms interfacial voids and cause the decrease in bond strength.

Fabrication of nano-scale Cu bond pads with seal design in 3D integration applications.

PubMed

Chen, K N; Tsang, C K; Wu, W W; Lee, S H; Lu, J Q

2011-04-01

A method to fabricate nano-scale Cu bond pads for improving bonding quality in 3D integration applications is reported. The effect of Cu bonding quality on inter-level via structural reliability for 3D integration applications is investigated. We developed a Cu nano-scale-height bond pad structure and fabrication process for improved bonding quality by recessing oxides using a combination of SiO2 CMP process and dilute HF wet etching. In addition, in order to achieve improved wafer-level bonding, we introduced a seal design concept that prevents corrosion and provides extra mechanical support. Demonstrations of these concepts and processes provide the feasibility of reliable nano-scale 3D integration applications.

Ultrasonic friction power during Al wire wedge-wedge bonding

NASA Astrophysics Data System (ADS)

Shah, A.; Gaul, H.; Schneider-Ramelow, M.; Reichl, H.; Mayer, M.; Zhou, Y.

2009-07-01

Al wire bonding, also called ultrasonic wedge-wedge bonding, is a microwelding process used extensively in the microelectronics industry for interconnections to integrated circuits. The bonding wire used is a 25μm diameter AlSi1 wire. A friction power model is used to derive the ultrasonic friction power during Al wire bonding. Auxiliary measurements include the current delivered to the ultrasonic transducer, the vibration amplitude of the bonding tool tip in free air, and the ultrasonic force acting on the bonding pad during the bond process. The ultrasonic force measurement is like a signature of the bond as it allows for a detailed insight into mechanisms during various phases of the process. It is measured using piezoresistive force microsensors integrated close to the Al bonding pad (Al-Al process) on a custom made test chip. A clear break-off in the force signal is observed, which is followed by a relatively constant force for a short duration. A large second harmonic content is observed, describing a nonsymmetric deviation of the signal wave form from the sinusoidal shape. This deviation might be due to the reduced geometrical symmetry of the wedge tool. For bonds made with typical process parameters, several characteristic values used in the friction power model are determined. The ultrasonic compliance of the bonding system is 2.66μm/N. A typical maximum value of the relative interfacial amplitude of ultrasonic friction is at least 222nm. The maximum interfacial friction power is at least 11.5mW, which is only about 4.8% of the total electrical power delivered to the ultrasonic generator.

Effect of gold wire bonding process on angular correlated color temperature uniformity of white light-emitting diode.

PubMed

Wu, Bulong; Luo, Xiaobing; Zheng, Huai; Liu, Sheng

2011-11-21

Gold wire bonding is an important packaging process of lighting emitting diode (LED). In this work, we studied the effect of gold wire bonding on the angular uniformity of correlated color temperature (CCT) in white LEDs whose phosphor layers were coated by freely dispersed coating process. Experimental study indicated that different gold wire bonding impacts the geometry of phosphor layer, and it results in different fluctuation trends of angular CCT at different spatial planes in one LED sample. It also results in various fluctuating amplitudes of angular CCT distributions at the same spatial plane for samples with different wire bonding angles. The gold wire bonding process has important impact on angular uniformity of CCT in LED package. © 2011 Optical Society of America

KIC 9821622: An interesting lithium-rich giant in the Kepler field

NASA Astrophysics Data System (ADS)

Jofré, E.; Petrucci, R.; García, L.; Gómez, M.

2015-12-01

We report the discovery of a new exceptional young lithium-rich giant, KIC 9821622, in the Kepler field that exhibits an unusually large enhancement of α, Fe-peak, and r-process elements. From high-resolution spectra obtained with GRACES at Gemini North, we derived fundamental parameters and detailed chemical abundances of 23 elements from equivalent widths and synthesis analysis. By combining atmospheric stellar parameters with available asteroseismic data, we obtained the stellar mass, radius, and age. The data analysis reveals that KIC 9821622 is a Li-rich (A(Li)NLTE = 1.80 ± 0.2) intermediate-mass giant star (M = 1.64 M⊙) located at the red giant branch near the luminosity bump. We find unexpectedly elevated abundances of Fe-peak and r-process elements. In addition, as previously reported, we find that this is a young star (2.37 Gyr) with unusually high abundances of α-elements ([α/Fe] = 0.31). The evolutionary status of KIC 9821622 suggests that its Li-rich nature is the result of internal fresh Li that is synthesized through the Cameron-Fowler mechanism near the luminosity bump. However, its peculiar enhancement of α, Fe-peak, and r-process elements opens the possibility of external contamination by material enriched by a supernova explosion. Although it is less likely, planet accretion cannot be ruled out. Based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministério da Ciência, Tecnologia e Inovação (Brazil) and Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina).Appendix A is available in electronic form at http://www.aanda.org

Heroin: MedlinePlus Health Topic

MedlinePlus

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Development of Statistical Process Control Methodology for an Environmentally Compliant Surface Cleaning Process in a Bonding Laboratory

NASA Technical Reports Server (NTRS)

Hutchens, Dale E.; Doan, Patrick A.; Boothe, Richard E.

1997-01-01

Bonding labs at both MSFC and the northern Utah production plant prepare bond test specimens which simulate or witness the production of NASA's Reusable Solid Rocket Motor (RSRM). The current process for preparing the bonding surfaces employs 1,1,1-trichloroethane vapor degreasing, which simulates the current RSRM process. Government regulations (e.g., the 1990 Amendments to the Clean Air Act) have mandated a production phase-out of a number of ozone depleting compounds (ODC) including 1,1,1-trichloroethane. In order to comply with these regulations, the RSRM Program is qualifying a spray-in-air (SIA) precision cleaning process using Brulin 1990, an aqueous blend of surfactants. Accordingly, surface preparation prior to bonding process simulation test specimens must reflect the new production cleaning process. The Bonding Lab Statistical Process Control (SPC) program monitors the progress of the lab and its capabilities, as well as certifies the bonding technicians, by periodically preparing D6AC steel tensile adhesion panels with EA-91 3NA epoxy adhesive using a standardized process. SPC methods are then used to ensure the process is statistically in control, thus producing reliable data for bonding studies, and identify any problems which might develop. Since the specimen cleaning process is being changed, new SPC limits must be established. This report summarizes side-by-side testing of D6AC steel tensile adhesion witness panels and tapered double cantilevered beams (TDCBs) using both the current baseline vapor degreasing process and a lab-scale spray-in-air process. A Proceco 26 inches Typhoon dishwasher cleaned both tensile adhesion witness panels and TDCBs in a process which simulates the new production process. The tests were performed six times during 1995, subsequent statistical analysis of the data established new upper control limits (UCL) and lower control limits (LCL). The data also demonstrated that the new process was equivalent to the vapor degreasing process.

Advanced Flip Chips in Extreme Temperature Environments

NASA Technical Reports Server (NTRS)

Ramesham, Rajeshuni

2010-01-01

The use of underfill materials is necessary with flip-chip interconnect technology to redistribute stresses due to mismatching coefficients of thermal expansion (CTEs) between dissimilar materials in the overall assembly. Underfills are formulated using organic polymers and possibly inorganic filler materials. There are a few ways to apply the underfills with flip-chip technology. Traditional capillary-flow underfill materials now possess high flow speed and reduced time to cure, but they still require additional processing steps beyond the typical surface-mount technology (SMT) assembly process. Studies were conducted using underfills in a temperature range of -190 to 85 C, which resulted in an increase of reliability by one to two orders of magnitude. Thermal shock of the flip-chip test articles was designed to induce failures at the interconnect sites (-40 to 100 C). The study on the reliability of flip chips using underfills in the extreme temperature region is of significant value for space applications. This technology is considered as an enabling technology for future space missions. Flip-chip interconnect technology is an advanced electrical interconnection approach where the silicon die or chip is electrically connected, face down, to the substrate by reflowing solder bumps on area-array metallized terminals on the die to matching footprints of solder-wettable pads on the chosen substrate. This advanced flip-chip interconnect technology will significantly improve the performance of high-speed systems, productivity enhancement over manual wire bonding, self-alignment during die joining, low lead inductances, and reduced need for attachment of precious metals. The use of commercially developed no-flow fluxing underfills provides a means of reducing the processing steps employed in the traditional capillary flow methods to enhance SMT compatibility. Reliability of flip chips may be significantly increased by matching/tailoring the CTEs of the substrate material and the silicon die or chip, and also the underfill materials. Advanced packaging interconnects technology such as flip-chip interconnect test boards have been subjected to various extreme temperature ranges that cover military specifications and extreme Mars and asteroid environments. The eventual goal of each process step and the entire process is to produce components with 100 percent interconnect and satisfy the reliability requirements. Underfill materials, in general, may possibly meet demanding end use requirements such as low warpage, low stress, fine pitch, high reliability, and high adhesion.

Joining engineering ceramics

NASA Astrophysics Data System (ADS)

Loehman, Ronald E.

Methods for joining ceramics are outlined with attention given to their fundamental properties, and some examples of ceramic bonding in engineering ceramic systems are presented. Ceramic-ceramic bonds using no filler material include diffusion and electric-field bonding and ceramic welding, and bonds with filler materials can be provided by Mo-Mn brazing, microwave joining, and reactive nonmetallic liquid bonding. Ceramic-metal joints can be effected with filler material by means of the same ceramic-ceramic processes and without filler material by means of use of molten glass or diffusion bonding. Key properties of the bonding processes include: bonds with discontinuous material properties, energies that are positive relative to the bulk material, and unique chemical and mechanical properties. The processes and properties are outlined for ceramic-metal joints and for joining silicon nitride, and the factors that control wetting, adhesion, and reaction on the atomic scale are critical for establishing successful joints.

Effect of thermal-convection-induced defects on the performance of perovskite solar cells

NASA Astrophysics Data System (ADS)

Ye, Fei; Xie, Fengxian; Yin, Maoshu; He, Jinjin; Wang, Yanbo; Tang, Wentao; Chen, Han; Yang, Xudong; Han, Liyuan

2017-07-01

Thermal-convection-induced defects can cause huge loss in the power conversion efficiency of solution-processed perovskite solar cells. We investigated two types of convection in perovskite solution during the formation of perovskite films. By balancing the convection via special configurations of surface tension and boiling point in mixed γ-butyrolactone (GBL) and dimethylsulfoxide (DMSO), we removed microscopic defects such as rings, bumps, and crevices. The deposited perovskite films were smooth and dense, which enabled a high power conversion efficiency of 17.7% in a 1 cm2 cell area. We believe that the present strategy for controlling the convection can be helpful in improving the perovskite film quality for solvent-rich scalable solution processes of solar cells such as doctor blading, soft-cover deposition, printing, and slot-die coating.

Solder extrusion pressure bonding process and bonded products produced thereby

DOEpatents

Beavis, L.C.; Karnowsky, M.M.; Yost, F.G.

1992-06-16

Disclosed is a process for production of soldered joints which are highly reliable and capable of surviving 10,000 thermal cycles between about [minus]40 C and 110 C. Process involves interposing a thin layer of a metal solder composition between the metal surfaces of members to be bonded and applying heat and up to about 1000 psi compression pressure to the superposed members, in the presence of a reducing atmosphere, to extrude the major amount of the solder composition, contaminants including fluxing gases and air, from between the members being bonded, to form a very thin, strong intermetallic bonding layer having a thermal expansion tolerant with that of the bonded members.

Diffusion bonding aeroengine components

NASA Astrophysics Data System (ADS)

Fitzpatrick, G. A.; Broughton, T.

1988-10-01

The use of diffusion bonding processes at Rolls-Royce for the manufacture of titanium-alloy aircraft engine components and structures is described. A liquid-phase diffusion bonding process called activated diffusion bonding has been developed for the manufacture of the hollow titanium wide chord fan blade. In addition, solid-state diffusion bonding is being used in the manufacture of hollow vane/blade airfoil constructions mainly in conjunction with superplastic forming and hot forming techniques.

Plates for vacuum thermal fusion

DOEpatents

Davidson, James C.; Balch, Joseph W.

2002-01-01

A process for effectively bonding arbitrary size or shape substrates. The process incorporates vacuum pull down techniques to ensure uniform surface contact during the bonding process. The essence of the process for bonding substrates, such as glass, plastic, or alloys, etc., which have a moderate melting point with a gradual softening point curve, involves the application of an active vacuum source to evacuate interstices between the substrates while at the same time providing a positive force to hold the parts to be bonded in contact. This enables increasing the temperature of the bonding process to ensure that the softening point has been reached and small void areas are filled and come in contact with the opposing substrate. The process is most effective where at least one of the two plates or substrates contain channels or grooves that can be used to apply vacuum between the plates or substrates during the thermal bonding cycle. Also, it is beneficial to provide a vacuum groove or channel near the perimeter of the plates or substrates to ensure bonding of the perimeter of the plates or substrates and reduce the unbonded regions inside the interior region of the plates or substrates.

Bumps on the road to Magnet designation: achieving organizational excellence.

PubMed

Steinbinder, Amy

2009-01-01

The chief nursing officer is in a unique position to guide his or her organization to excellence by creating a compelling vision; maintaining objectivity regarding the nursing department's accomplishments; holding senior nurse leaders accountable as Magnet champions; demonstrating strategic thinking, business planning development, operational connection, and awareness of clinical aspects of care; and establishing levels of ownership and decision making within the nursing department's operational framework. The clear definition of terms including responsibility, authority, delegation, accountability, and empowerment are necessary and, coupled with specific actions, skills, and measures of success, guide individual and group processes to achieve organizational excellence and ultimately Magnet designation.

Soft gamma rays from black holes versus neutron stars

NASA Technical Reports Server (NTRS)

Liang, Edison P.

1992-01-01

The recent launches of GRANAT and GRO provide unprecedented opportunities to study compact collapsed objects from their hard x ray and gamma ray emissions. The spectral range above 100 keV can now be explored with much higher sensitivity and time resolution than before. The soft gamma ray spectral data is reviewed of black holes and neutron stars, radiation, and particle energization mechanisms and potentially distinguishing gamma ray signatures. These may include soft x ray excesses versus deficiencies, thermal versus nonthermal processes, transient gamma ray bumps versus power law tails, lines, and periodicities. Some of the highest priority future observations are outlines which will shed much light on such systems.

Asymmetric (1+1)-dimensional hydrodynamics in high-energy collisions

NASA Astrophysics Data System (ADS)

Bialas, A.; Peschanski, R.

2011-05-01

The possibility that particle production in high-energy collisions is a result of two asymmetric hydrodynamic flows is investigated using the Khalatnikov form of the (1+1)-dimensional approximation of hydrodynamic equations. The general solution is discussed and applied to the physically appealing “generalized in-out cascade” where the space-time and energy-momentum rapidities are equal at initial temperature but boost invariance is not imposed. It is demonstrated that the two-bump structure of the entropy density, characteristic of the asymmetric input, changes easily into a single broad maximum compatible with data on particle production in symmetric processes. A possible microscopic QCD interpretation of asymmetric hydrodynamics is proposed.

Effect of processing parameters on reaction bonding of silicon nitride

NASA Technical Reports Server (NTRS)

Richman, M. H.; Gregory, O. J.; Magida, M. B.

1980-01-01

Reaction bonded silicon nitride was developed. The relationship between the various processing parameters and the resulting microstructures was to design and synthesize reaction bonded materials with improved room temperature mechanical properties.

Dynamics and Afterglow Light Curves of Gamma-Ray Burst Blast Waves Encountering a Density Bump or Void

NASA Astrophysics Data System (ADS)

Uhm, Z. Lucas; Zhang, Bing

2014-07-01

We investigate the dynamics and afterglow light curves of gamma-ray burst blast waves that encounter various density structures (such as bumps, voids, or steps) in the surrounding ambient medium. We present and explain the characteristic response features that each type of density structure in the medium leaves on the forward shock (FS) and reverse shock (RS) dynamics for blast waves with either a long-lived or short-lived RS. We show that when the ambient medium density drops, the blast waves exhibit in some cases a period of an actual acceleration (even during their deceleration stage) due to adiabatic cooling of blast waves. Comparing numerical examples that have different shapes of bumps or voids, we propose a number of consistency tests that must be satisfied by correct modeling of blast waves. Our model results successfully pass these tests. Employing a Lagrangian description of blast waves, we perform a sophisticated calculation of afterglow emission. We show that as a response to density structures in the ambient medium, the RS light curves produce more significant variations than the FS light curves. Some observed features (such as rebrightenings, dips, or slow wiggles) can be more easily explained within the RS model. We also discuss the origin of these different features imprinted on the FS and RS light curves.

Search for the Antineutrino rest mass in the tritium beta decay

NASA Astrophysics Data System (ADS)

Lobashev, V. M.

Status and results of the tritium beta spectrum measurement on the “Troitsk ν-mass” set-up are discussed. Measurements carried out in 1994 to 1997 provided the lowest upper limit for electron antineutrino rest mass in the direct kinematics approach. Analysis of the spectrum revealed a narrow (less than 5 eV wide) bump-like structure located 5 to 12 eV below the end point with integral intensity ∼ 7·10 -11 of the total decay rate. A specific feature of this structure proved to be a drift of the position of the bump during 3 years of measurement. No other visible anomalies in the measured part of the spectrum were found after introduction of a correction for an effect of electron trapping in the source. After accounting for the bump, the shape of the whole measured part of the beta spectrum agrees with zero mν2, thus eliminating the problem of “negative mν2”. The combined result of the 94 and 96 runs without the 97 run data is: m ν2=1.5±5.9 stat±3.6 syst{eV 2}/{C 4} From here most conservative limit for the neutrino mass is: m ν < 3.8 {eV}/{c 2} at 95 % C.L. A new type of differential spectrometer, based on adiabatisity principle is proposed.

ARE ULTRA-LONG GAMMA-RAY BURSTS CAUSED BY BLUE SUPERGIANT COLLAPSARS, NEWBORN MAGNETARS, OR WHITE DWARF TIDAL DISRUPTION EVENTS?

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

Ioka, Kunihito; Hotokezaka, Kenta; Piran, Tsvi, E-mail: kunihito.ioka@yukawa.kyoto-u.ac.jp

Ultra-long gamma-ray bursts (ulGRBs) are a new population of GRBs with extreme durations of ∼10{sup 4} s. Leading candidates for their origin are blue supergiant collapsars, magnetars, and white dwarf tidal disruption events (WD-TDEs) caused by massive black holes (BHs). Recent observations of supernova-like (SN-like) bumps associated with ulGRBs challenged both the WD-TDE and the blue supergiant models because of the detection of SNe and the absence of hydrogen lines, respectively. We propose that WD-TDEs can accommodate the observed SN-like bumps if the fallback WD matter releases energy into the unbound WD ejecta. The observed ejecta energy, luminosity, and velocitymore » are explained by the gravitational energy, Eddington luminosity, and escape velocity of the formed accretion disk, respectively. We also show that the observed X-rays can ionize the ejecta, eliminating lines. The SN-like light curves (SN 2011kl) for the ulGRB 111209A are consistent with all three models, although a magnetar model is unnatural because the spin-down time required to power the SN-like bump is a hundred times longer than the GRB. Our results imply that TDEs are a possible energy source for SN-like events in general and for ulGRBs in particular.« less

Fluid aspects of electron streaming instability in electron-ion plasmas

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

Jao, C.-S.; Hau, L.-N.; Department of Physics, National Central University, Jhongli, Taiwan

2014-02-15

Electrons streaming in a background electron and ion plasma may lead to the formation of electrostatic solitary wave (ESW) and hole structure which have been observed in various space plasma environments. Past studies on the formation of ESW are mostly based on the particle simulations due to the necessity of incorporating particle's trapping effects. In this study, the fluid aspects and thermodynamics of streaming instabilities in electron-ion plasmas including bi-streaming and bump-on-tail instabilities are addressed based on the comparison between fluid theory and the results from particle-in-cell simulations. The energy closure adopted in the fluid model is the polytropic lawmore » of d(pρ{sup −γ})/dt=0 with γ being a free parameter. Two unstable modes are identified for the bump-on-tail instability and the growth rates as well as the dispersion relation of the streaming instabilities derived from the linear theory are found to be in good agreement with the particle simulations for both bi-streaming and bump-on-tail instabilities. At the nonlinear saturation, 70% of the electrons are trapped inside the potential well for the drift velocity being 20 times of the thermal velocity and the pρ{sup −γ} value is significantly increased. Effects of ion to electron mass ratio on the linear fluid theory and nonlinear simulations are also examined.« less

Spatial Convergence of Three Dimensional Turbulent Flows

NASA Technical Reports Server (NTRS)

Park, Michael A.; Anderson, W. Kyle

2016-01-01

Finite-volume and finite-element schemes, both implemented within the FUN3D flow solver, are evaluated for several test cases described on the Turbulence-Modeling Resource (TMR) web site. The cases include subsonic flow over a hemisphere cylinder, subsonic flow over a swept bump configuration, and supersonic flow in a square duct. The finite- volume and finite-element schemes are both used to obtain solutions for the first two cases, whereas only the finite-volume scheme is used for the supersonic duct. For the hemisphere cylinder, finite-element solutions obtained on tetrahedral meshes are compared with finite- volume solutions on mixed-element meshes. For the swept bump, finite-volume solutions have been obtained for both hexahedral and tetrahedral meshes and are compared with finite-element solutions obtained on tetrahedral meshes. For the hemisphere cylinder and the swept bump, solutions are obtained on a series of meshes with varying grid density and comparisons are made between drag coefficients, pressure distributions, velocity profiles, and profiles of the turbulence working variable. The square duct shows small variation due to element type or the spatial accuracy of turbulence model convection. It is demonstrated that the finite-element scheme on tetrahedral meshes yields similar accuracy as the finite- volume scheme on mixed-element and hexahedral grids, and demonstrates less sensitivity to the mesh topology (biased tetrahedral grids) than the finite-volume scheme.

Dynamics and afterglow light curves of gamma-ray burst blast waves encountering a density bump or void

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

Uhm, Z. Lucas; Zhang, Bing, E-mail: uhm@pku.edu.cn, E-mail: zhang@physics.unlv.edu

2014-07-01

We investigate the dynamics and afterglow light curves of gamma-ray burst blast waves that encounter various density structures (such as bumps, voids, or steps) in the surrounding ambient medium. We present and explain the characteristic response features that each type of density structure in the medium leaves on the forward shock (FS) and reverse shock (RS) dynamics for blast waves with either a long-lived or short-lived RS. We show that when the ambient medium density drops, the blast waves exhibit in some cases a period of an actual acceleration (even during their deceleration stage) due to adiabatic cooling of blastmore » waves. Comparing numerical examples that have different shapes of bumps or voids, we propose a number of consistency tests that must be satisfied by correct modeling of blast waves. Our model results successfully pass these tests. Employing a Lagrangian description of blast waves, we perform a sophisticated calculation of afterglow emission. We show that as a response to density structures in the ambient medium, the RS light curves produce more significant variations than the FS light curves. Some observed features (such as rebrightenings, dips, or slow wiggles) can be more easily explained within the RS model. We also discuss the origin of these different features imprinted on the FS and RS light curves.« less

The role of visuohaptic experience in visually perceived depth.

PubMed

Ho, Yun-Xian; Serwe, Sascha; Trommershäuser, Julia; Maloney, Laurence T; Landy, Michael S

2009-06-01

Berkeley suggested that "touch educates vision," that is, haptic input may be used to calibrate visual cues to improve visual estimation of properties of the world. Here, we test whether haptic input may be used to "miseducate" vision, causing observers to rely more heavily on misleading visual cues. Human subjects compared the depth of two cylindrical bumps illuminated by light sources located at different positions relative to the surface. As in previous work using judgments of surface roughness, we find that observers judge bumps to have greater depth when the light source is located eccentric to the surface normal (i.e., when shadows are more salient). Following several sessions of visual judgments of depth, subjects then underwent visuohaptic training in which haptic feedback was artificially correlated with the "pseudocue" of shadow size and artificially decorrelated with disparity and texture. Although there were large individual differences, almost all observers demonstrated integration of haptic cues during visuohaptic training. For some observers, subsequent visual judgments of bump depth were unaffected by the training. However, for 5 of 12 observers, training significantly increased the weight given to pseudocues, causing subsequent visual estimates of shape to be less veridical. We conclude that haptic information can be used to reweight visual cues, putting more weight on misleading pseudocues, even when more trustworthy visual cues are available in the scene.

Hives (Urticaria)

MedlinePlus

... look like tiny little spots, blotches, or large connected bumps. Individual hives can last anywhere from a ... cold or place a sandbag or other heavy object on your thighs to see if the pressure ...

7 CFR 51.3154 - Well formed.

Code of Federal Regulations, 2010 CFR

2010-01-01

... FRESH FRUITS, VEGETABLES AND OTHER PRODUCTS 1,2 (INSPECTION, CERTIFICATION, AND STANDARDS) United States... has the shape characteristic of the variety and that bumps or other roughness do not materially...

Genital Warts

MedlinePlus

... transmitted disease (STD) caused by the human papillomavirus (HPV). The warts usually appear as a small bump ... completely eliminate, the risk of catching or spreading HPV. The most reliable way to avoid infection is ...

Mechanics of wafer bonding: Effect of clamping

NASA Astrophysics Data System (ADS)

Turner, K. T.; Thouless, M. D.; Spearing, S. M.

2004-01-01

A mechanics-based model is developed to examine the effects of clamping during wafer bonding processes. The model provides closed-form expressions that relate the initial geometry and elastic properties of the wafers to the final shape of the bonded pair and the strain energy release rate at the interface for two different clamping configurations. The results demonstrate that the curvature of bonded pairs may be controlled through the use of specific clamping arrangements during the bonding process. Furthermore, it is demonstrated that the strain energy release rate depends on the clamping configuration and that using applied loads usually leads to an undesirable increase in the strain energy release rate. The results are discussed in detail and implications for process development and bonding tool design are highlighted.

Bidirectional reflection functions from surface bump maps

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

Cabral, B.; Max, N.; Springmeyer, R.

1987-04-29

The Torrance-Sparrow model for calculating bidirectional reflection functions contains a geometrical attenuation factor to account for shadowing and occlusions in a hypothetical distribution of grooves on a rough surface. Using an efficient table-based method for determining the shadows and occlusions, we calculate the geometric attenuation factor for surfaces defined by a specific table of bump heights. Diffuse and glossy specular reflection of the environment can be handled in a unified manner by using an integral of the bidirectional reflection function times the environmental illumination, over the hemisphere of solid angle above a surface. We present a method of estimating themore » integral, by expanding the bidirectional reflection coefficient in spherical harmonics, and show how the coefficients in this expansion can be determined efficiently by reorganizing our geometric attenuation calculation.« less

Cruise tap versus handshake: using common sense to reduce hand contamination and germ transmission on cruise ships.

PubMed

Dahl, Eilif

2016-01-01

A firm handshake is a widely used greeting, but contaminated fingers and palms can also transfer bacteria and virus. Hand sanitation is important to prevent spreading of contagious diseases, but to wash hands properly takes too much time to ensure satisfactory compliance. Banning the handshake from health care settings has been proposed, but an alternative, less contagious form of greeting must be substituted. Cruise ships are particular vulnerable to infectious diseases that are transferred from person to person. The fist bump, common in some subcultures, has become increasing popular as the greeting-of-choice on smaller cruise vessels. To further reduce the contact area, a modification of the fist bump, the 'cruise tap', where only two knuckles briefly touch each other, is recommended.

Expressions for the spherical-wave-structure function based on a bump spectrum model for the index of refraction

NASA Astrophysics Data System (ADS)

Richardson, Christina E.; Andrews, Larry C.

1991-07-01

New spectra models have recently been developed for the spatial power spectra of temperature and refractive index fluctuations in the atmospheric boundary layer showing the characteristic 'bump' just prior to the dissipation ranges. Theoretical work involving these new models has led to new expressions for the phase structure function associated with a plane optical wave, although most experimental work has involved spherical waves. Following techniques similar to those used for the plane wave analysis, new expressions valid in geometrical and diffraction regimes are developed here for the phase structure function of a spherical optical wave propagating through clear-air atmospheric turbulence. Useful asymptotic formulas for small separation distances and the inertial subrange are derived from these general expressions.

Rapid adhesive bonding concepts

NASA Technical Reports Server (NTRS)

Stein, B. A.; Tyeryar, J. R.; Hodges, W. T.

1984-01-01

Adhesive bonding in the aerospace industry typically utilizes autoclaves or presses which have considerable thermal mass. As a consequence, the rates of heatup and cooldown of the bonded parts are limited and the total time and cost of the bonding process is often relatively high. Many of the adhesives themselves do not inherently require long processing times. Bonding could be performed rapidly if the heat was concentrated in the bond lines or at least in the adherends. Rapid adhesive bonding concepts were developed to utilize induction heating techniques to provide heat directly to the bond line and/or adherends without heating the entire structure, supports, and fixtures of a bonding assembly. Bonding times for specimens are cut by a factor of 10 to 100 compared to standard press bonding. The development of rapid adhesive bonding for lap shear specimens (per ASTM D1003 and D3163), for aerospace panel bonding, and for field repair needs of metallic and advanced fiber reinforced polymeric matrix composite structures are reviewed.

Living olefin polymerization processes

DOEpatents

Schrock, Richard R.; Baumann, Robert

1999-01-01

Processes for the living polymerization of olefin monomers with terminal carbon-carbon double bonds are disclosed. The processes employ initiators that include a metal atom and a ligand having two group 15 atoms and a group 16 atom or three group 15 atoms. The ligand is bonded to the metal atom through two anionic or covalent bonds and a dative bond. The initiators are particularly stable under reaction conditions in the absence of olefin monomer. The processes provide polymers having low polydispersities, especially block copolymers having low polydispersities. It is an additional advantage of these processes that, during block copolymer synthesis, a relatively small amount of homopolymer is formed.

Living olefin polymerization processes

DOEpatents

Schrock, R.R.; Baumann, R.

1999-03-30

Processes for the living polymerization of olefin monomers with terminal carbon-carbon double bonds are disclosed. The processes employ initiators that include a metal atom and a ligand having two group 15 atoms and a group 16 atom or three group 15 atoms. The ligand is bonded to the metal atom through two anionic or covalent bonds and a dative bond. The initiators are particularly stable under reaction conditions in the absence of olefin monomer. The processes provide polymers having low polydispersities, especially block copolymers having low polydispersities. It is an additional advantage of these processes that, during block copolymer synthesis, a relatively small amount of homopolymer is formed.

Living olefin polymerization processes

DOEpatents

Schrock, Richard R.; Baumann, Robert

2003-08-26

Processes for the living polymerization of olefin monomers with terminal carbon-carbon double bonds are disclosed. The processes employ initiators that include a metal atom and a ligand having two group 15 atoms and a group 16 atom or three group 15 atoms. The ligand is bonded to the metal atom through two anionic or covalent bonds and a dative bond. The initiators are particularly stable under reaction conditions in the absence of olefin monomer. The processes provide polymers having low polydispersities, especially block copolymers having low polydispersities. It is an additional advantage of these processes that, during block copolymer synthesis, a relatively small amount of homopolymer is formed.

Living olefin polymerization processes

DOEpatents

Schrock, Richard R.; Bauman, Robert

2006-11-14

Processes for the living polymerization of olefin monomers with terminal carbon-carbon double bonds are disclosed. The processes employ initiators that include a metal atom and a ligand having two group 15 atoms and a group 16 atom or three group 15 atoms. The ligand is bonded to the metal atom through two anionic or covalent bonds and a dative bond. The initiators are particularly stable under reaction conditions in the absence of olefin monomer. The processes provide polymers having low polydispersities, especially block copolymers having low polydispersities. It is an additional advantage of these processes that, during block copolymer synthesis, a relatively small amount of homopolymer is formed.

Numerical and Experimental Characterization of a Composite Secondary Bonded Adhesive Lap Joint Using the Ultrasonics method

NASA Astrophysics Data System (ADS)

Kumar, M. R.; Ghosh, A.; Karuppannan, D.

2018-05-01

The construction of aircraft using advanced composites have become very popular during the past two decades, in which many innovative manufacturing processes, such as cocuring, cobonding, and secondary bonding processes, have been adopted. The secondary bonding process has become less popular than the other two ones because of nonavailability of process database and certification issues. In this article, an attempt is made to classify the quality of bonding using nondestructive ultrasonic inspection methods. Specimens were prepared and tested using the nondestructive ultrasonic Through Transmission (TT), Pulse Echo (PE), and air coupled guided wave techniques. It is concluded that the ultrasonic pulse echo technique is the best one for inspecting composite secondary bonded adhesive joints.

Chip bonding of low-melting eutectic alloys by transmitted laser radiation

NASA Astrophysics Data System (ADS)

Hoff, Christian; Venkatesh, Arjun; Schneider, Friedrich; Hermsdorf, Jörg; Bengsch, Sebastian; Wurz, Marc C.; Kaierle, Stefan; Overmeyer, Ludger

2017-06-01

Present-day thermode bond systems for the assembly of radio-frequency identification (RFID) chips are mechanically inflexible, difficult to control, and will not meet future manufacturing challenges sufficiently. Chip bonding, one of the key processes in the production of integrated circuits (ICs), has a high potential for optimization with respect to process duration and process flexibility. For this purpose, the technologies used, so far, are supposed to be replaced by a transmission laser-bonding process using low-melting eutectic alloys. In this study, successful bonding investigations of mock silicon chips and of RFID chips on flexible polymer substrates are presented using the low-melting eutectic alloy, 52In48Sn, and a laser with a wavelength of 2 μm.

Investigation on the diffusion bonding of tungsten and EUROFER97

NASA Astrophysics Data System (ADS)

Basuki, Widodo Widjaja; Aktaa, Jarir

2011-10-01

Due to its advantages, tungsten is selected as armor and structural material for use in future fusion power plants. To apply tungsten as structural material, a joint to EUROFER97 is foreseen in current divertor design for which the diffusion bonding is considered in this work. The joining must have acceptable strength and ductility without significant change in microstructures. So far, numerous diffusion bonding experiments without and with post bonding heat treatment (PBHT) are performed at 1050 °C for various bonding duration. For the bonding processes without PBHT, the bonding seams obtained are defect free and have a very high tensile strength. However they are brittle due to a thin layer of FeW intermetallic phase and metal carbides. For the bonding processes with PBHT, the bonding specimens fail at the bonding seam.

Perception of shapes targeting local and global processes in autism spectrum disorders.

PubMed

Grinter, Emma J; Maybery, Murray T; Pellicano, Elizabeth; Badcock, Johanna C; Badcock, David R

2010-06-01

Several researchers have found evidence for impaired global processing in the dorsal visual stream in individuals with autism spectrum disorders (ASDs). However, support for a similar pattern of visual processing in the ventral visual stream is less consistent. Critical to resolving the inconsistency is the assessment of local and global form processing ability. Within the visual domain, radial frequency (RF) patterns - shapes formed by sinusoidally varying the radius of a circle to add 'bumps' of a certain number to a circle - can be used to examine local and global form perception. Typically developing children and children with an ASD discriminated between circles and RF patterns that are processed either locally (RF24) or globally (RF3). Children with an ASD required greater shape deformation to identify RF3 shapes compared to typically developing children, consistent with difficulty in global processing in the ventral stream. No group difference was observed for RF24 shapes, suggesting intact local ventral-stream processing. These outcomes support the position that a deficit in global visual processing is present in ASDs, consistent with the notion of Weak Central Coherence.

Low-temperature wafer direct bonding of silicon and quartz glass by a two-step wet chemical surface cleaning

NASA Astrophysics Data System (ADS)

Wang, Chenxi; Xu, Jikai; Zeng, Xiaorun; Tian, Yanhong; Wang, Chunqing; Suga, Tadatomo

2018-02-01

We demonstrate a facile bonding process for combining silicon and quartz glass wafers by a two-step wet chemical surface cleaning. After a post-annealing at 200 °C, strong bonding interfaces with no defects or microcracks were obtained. On the basis of the detailed surface and bonding interface characterizations, the bonding mechanism was explored and discussed. The amino groups terminated on the cleaned surfaces might contribute to the bonding strength enhancement during the annealing. This cost-effective bonding process has great potentials for silicon- and glass-based heterogeneous integrations without requiring a vacuum system.

The bumpy light curve of Type IIn supernova iPTF13z over 3 years

NASA Astrophysics Data System (ADS)

Nyholm, A.; Sollerman, J.; Taddia, F.; Fremling, C.; Moriya, T. J.; Ofek, E. O.; Gal-Yam, A.; De Cia, A.; Roy, R.; Kasliwal, M. M.; Cao, Y.; Nugent, P. E.; Masci, F. J.

2017-08-01

A core-collapse (CC) supernova (SN) of Type IIn is dominated by the interaction of SN ejecta with the circumstellar medium (CSM). Some SNe IIn (e.g. SN 2006jd) have episodes of re-brightening ("bumps") in their light curves. We present iPTF13z, a Type IIn SN discovered on 2013 February 1 by the intermediate Palomar Transient Factory (iPTF). This SN showed at least five bumps in its declining light curve between 130 and 750 days after discovery. We analyse this peculiar behaviour and try to infer the properties of the CSM, of the SN explosion, and the nature of the progenitor star. We obtained multi-band optical photometry for over 1000 days after discovery with the P48 and P60 telescopes at Palomar Observatory. We obtained low-resolution optical spectra during the same period. We did an archival search for progenitor outbursts. We analyse the photometry and the spectra, and compare iPTF13z to other SNe IIn. In particular we derive absolute magnitudes, colours, a pseudo-bolometric light curve, and the velocities of the different components of the spectral lines. A simple analytical model is used to estimate the properties of the CSM. iPTF13z had a light curve peaking at Mr ≲ - 18.3 mag. The five bumps during its decline phase had amplitudes ranging from 0.4 to 0.9 mag and durations between 20 and 120 days. The most prominent bumps appeared in all the different optical bands, when covered. The spectra of this SN showed typical SN IIn characteristics, with emission lines of Hα (with broad component FWHM 103 - 104 km s-1 and narrow component FWHM 102 km s-1) and He I, but also with Fe II, Ca II, Na I D and Hβ P Cygni profiles (with velocities of 103km s-1). A pre-explosion outburst was identified lasting ≳ 50 days, with Mr ≈ - 15 mag around 210 days before discovery. Large, variable progenitor mass-loss rates (≳0.01M⊙ yr-1) and CSM densities (≳10-16 g cm-3) are derived. The SN was hosted by a metal-poor dwarf galaxy at redshift z = 0.0328. We suggest that the light curve bumps of iPTF13z arose from SN ejecta interacting with denser regions in the CSM, possibly produced by the eruptions of a luminous blue variable progenitor star. Full Tables A.2, A.3 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/605/A6

Franz Joseph Gall and music: the faculty and the bump.

PubMed

Eling, Paul; Finger, Stanley; Whitaker, Harry

2015-01-01

The traditional story maintains that Franz Joseph Gall's (1758-1828) scientific program began with his observations of schoolmates with bulging eyes and good verbal memories. But his search to understand human nature, in particular individual differences in capacities, passions, and tendencies, can also be traced to other important observations, one being of a young girl with an exceptional talent for music. Rejecting contemporary notions of cognition, Gall concluded that behavior results from the interaction of a limited set of basic faculties, each with its own processes for perception and memory, each with its own territory in both cerebral or cerebellar cortices. Gall identified 27 faculties, one being the sense of tone relations or music. The description of the latter is identical in both his Anatomie et Physiologie and Sur les Fonctions du Cerveau et sur Celles de Chacune de ses Parties, where he provided positive and negative evidences and discussed findings from humans and lower animals, for the faculty. The localization of the cortical faculty for talented musicians, he explained, is demonstrated by a "bump" on each side of the skull just above the angle of the eye; hence, the lower forehead of musicians is broader or squarer than in other individuals. Additionally, differences between singing and nonsinging birds also correlate with cranial features. Gall even brought age, racial, and national differences into the picture. What he wrote about music reveals much about his science and creative thinking. © 2015 Elsevier B.V. All rights reserved.

Disk irradiation and light curves of x ray novae

NASA Technical Reports Server (NTRS)

Kim, S.-W.; Wheeler, J. C.; Mineshige, S.

1994-01-01

We study the disk instability and the effect of irradiation on outbursts in the black hole X-ray nova system. In both the optical and soft X-rays, the light curves of several X-ray novae, A0620-00, GH 2000+25, Nova Muscae 1991 (GS 1124-68), and GRO J0422+32, show a main peak, a phase of exponential decline, a secondary maximum or reflare, and a final bump in the late decay followed by a rapid decline. Basic disk thermal limit cycle instabilities can account for the rapid rise and overall decline, but not the reflare and final bump. The rise time of the reflare, about 10 days, is too short to represent a viscous time, so this event is unlikely to be due to increased mass flow from the companion star. We explore the possibility that irradiation by X-rays produced in the inner disk can produce these secondary effects by enhancing the mass flow rate within the disk. Two plausible mechanisms of irradiation of the disk are considered: direct irradiation from the inner hot disk and reflected radiation from a corona or other structure above the disk. Both of these processes will be time dependent in the context of the disk instability model and result in more complex time-dependent behavior of the disk structure. We test both disk instability and mass transfer burst models for the secondary flares in the presence of irradiation.

Terahertz pulse generation from metal nanoparticle ink

NASA Astrophysics Data System (ADS)

Kato, Kosaku; Takano, Keisuke; Tadokoro, Yuzuru; Phan, Thanh Nhat Khoa; Nakajima, Makoto

2016-11-01

Terahertz pulse generation from metallic nanostructures irradiated by femtosecond laser pulses is of interest because the conversion efficiency from laser pulses to terahertz waves is increased by the local field enhancement resulting from the plasmon oscillation. In this talk we present our recent study on terahertz generation from metal nanoparticle ink. We baked a silver nanoparticle ink spin-coated onto a glass coverslip in various temperatures. On the surface of the baked ink, bumpy nanostructures are spontaneously formed, and the average size of bumps depends on the baking temperature. These structures are expected to lead to local field enhancement and then large nonlinear polarizations on the surface. The baked ink was irradiated by the output of regeneratively amplified Ti:sapphire femtosecond laser at an incidence angle of 45°. Waveforms of generated terahertz pulses are detected by electro-optical sampling. The generation efficiency was high when the average diameter of bumps was around 100 nm, which is realized when the ink is baked in 205 to 235°C in our setup. One of our next research targets is terahertz wave generation from micro-patterned metallic nanoparticle ink. It is an advantage of the metal nanoparticle ink that by using inkjet printers one can fabricate various patterns with micrometer scales, in which terahertz waves have a resonance. Combination of microstructures made by a printer and nanostructure spontaneously formed in the baking process will provide us terahertz emitters with unique frequency characteristics.

New method for rapid testing of bond strength for wood adhesives

Treesearch

James M. Wescott; Michael J. Birkeland; Amy E. Traska; Charles R. Frihart; Brice N. Dally

2007-01-01

In developing new adhesives for wood bonding, the testing of bond performance can often be a limiting factor in the development process. Evaluating the bond performance of an adhesive that can be prepared in less than a day often takes several days using standard performance tests. This testing slows the development process and may cause a company to abandon a...

27 CFR 40.135 - Strengthening bond.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 27 Alcohol, Tobacco Products and Firearms 2 2013-04-01 2013-04-01 false Strengthening bond. 40.135... PROCESSED TOBACCO Bonds and Extensions of Coverage of Bonds § 40.135 Strengthening bond. Where the amount of... immediately file a strengthening bond in an appropriate amount with the same surety as that on the bond...

27 CFR 40.135 - Strengthening bond.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 27 Alcohol, Tobacco Products and Firearms 2 2010-04-01 2010-04-01 false Strengthening bond. 40.135... PROCESSED TOBACCO Bonds and Extensions of Coverage of Bonds § 40.135 Strengthening bond. Where the amount of... immediately file a strengthening bond in an appropriate amount with the same surety as that on the bond...

27 CFR 40.135 - Strengthening bond.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 27 Alcohol, Tobacco Products and Firearms 2 2011-04-01 2011-04-01 false Strengthening bond. 40.135... PROCESSED TOBACCO Bonds and Extensions of Coverage of Bonds § 40.135 Strengthening bond. Where the amount of... immediately file a strengthening bond in an appropriate amount with the same surety as that on the bond...

27 CFR 40.135 - Strengthening bond.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 27 Alcohol, Tobacco Products and Firearms 2 2014-04-01 2014-04-01 false Strengthening bond. 40.135... PROCESSED TOBACCO Bonds and Extensions of Coverage of Bonds § 40.135 Strengthening bond. Where the amount of... immediately file a strengthening bond in an appropriate amount with the same surety as that on the bond...

27 CFR 40.135 - Strengthening bond.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 27 Alcohol, Tobacco Products and Firearms 2 2012-04-01 2011-04-01 true Strengthening bond. 40.135... PROCESSED TOBACCO Bonds and Extensions of Coverage of Bonds § 40.135 Strengthening bond. Where the amount of... immediately file a strengthening bond in an appropriate amount with the same surety as that on the bond...

Hives (Urticaria) (For Parents)

MedlinePlus

... look like tiny little spots, blotches, or large connected bumps. Individual hives can last anywhere from a ... cold or place a sandbag or other heavy object on the thighs to see if the pressure ...

Babies and heat rashes

MedlinePlus

... occurs in babies when the pores of the sweat glands become blocked. This happens most often when ... weather is hot or humid. As your infant sweats, little red bumps, and possibly tiny blisters, form ...

Effects of ice shelf basal melt variability on evolution of Thwaites Glacier

NASA Astrophysics Data System (ADS)

Hoffman, M. J.; Fyke, J. G.; Price, S. F.; Asay-Davis, X.; Perego, M.

2017-12-01

Theory, modeling, and observations indicate that marine ice sheets on a retrograde bed, including Thwaites Glacier, Antarctica, are only conditionally stable. Previous modeling studies have shown that rapid, unstable retreat can occur when steady ice-shelf basal melting causes the grounding line to retreat past restraining bedrock bumps. Here we explore the initiation and evolution of unstable retreat of Thwaites Glacier when the ice-shelf basal melt forcing includes temporal variability mimicking realistic climate variability. We use the three-dimensional, higher-order Model for Prediction Across Scales-Land Ice (MPASLI) model forced with an ice shelf basal melt parameterization derived from previous coupled ice sheet/ocean simulations. We add sinusoidal temporal variability to the melt parameterization that represents shoaling and deepening of Circumpolar Deep Water. We perform an ensemble of 250 year duration simulations with different values for the amplitude, period, and phase of the variability. Preliminary results suggest that, overall, variability leads to slower grounding line retreat and less mass loss than steady simulations. Short period (2 yr) variability leads to similar results as steady forcing, whereas decadal variability can result in up to one-third less mass loss. Differences in phase lead to a large range in mass loss/grounding line retreat, but it is always less than the steady forcing. The timing of ungrounding from each restraining bedrock bump, which is strongly affected by the melt variability, is the rate limiting factor, and variability-driven delays in ungrounding at each bump accumulate. Grounding line retreat in the regions between bedrock bumps is relatively unaffected by ice shelf melt variability. While the results are sensitive to the form of the melt parameterization and its variability, we conclude that decadal period ice shelf melt variability could potentially delay marine ice sheet instability by up to many decades. However, it does not alter the eventual mass loss and sea level rise at centennial scales. The potential differences are significant enough to highlight the need for further observations to constrain the amplitude and period of the modes of climate and ocean variability relevant to Antarctic ice shelf melting.

Blood pressure self-monitoring in pregnancy (BuMP) feasibility study; a qualitative analysis of women's experiences of self-monitoring.

PubMed

Hinton, Lisa; Tucker, Katherine L; Greenfield, Sheila M; Hodgkinson, James A; Mackillop, Lucy; McCourt, Christine; Carver, Trisha; Crawford, Carole; Glogowska, Margaret; Locock, Louise; Selwood, Mary; Taylor, Kathryn S; McManus, Richard J

2017-12-19

Hypertensive disorders in pregnancy are a leading cause of maternal and fetal morbidity worldwide. Raised blood pressure (BP) affects 10% of pregnancies worldwide, of which almost half develop pre-eclampsia. The proportion of pregnant women who have risk factors for pre-eclampsia (such as pre-existing hypertension, obesity and advanced maternal age) is increasing. Pre-eclampsia can manifest itself before women experience symptoms and can develop between antenatal visits. Incentives to improve early detection of gestational hypertensive disorders are therefore strong and self-monitoring of blood pressure (SMBP) in pregnancy might be one means to achieve this, whilst improving women's involvement in antenatal care. The Blood Pressure Self-Monitoring in Pregnancy (BuMP) study aimed to evaluate the feasibility and acceptability of SMBP in pregnancy. To understand women's experiences of SMBP during pregnancy, we undertook a qualitative study embedded within the BuMP observational feasibility study. Women who were at higher risk of developing hypertension and/or pre-eclampsia were invited to take part in a study using SMBP and also invited to take part in an interview. Semi-structured interviews were conducted at the women's homes in Oxfordshire and Birmingham with women who were self-monitoring their BP as part of the BuMP feasibility study in 2014. Interviews were conducted by a qualitative researcher and transcribed verbatim. A framework approach was used for analysis. Fifteen women agreed to be interviewed. Respondents reported general willingness to engage with monitoring their own BP, feeling that it could reduce anxiety around their health during pregnancy, particularly if they had previous experience of raised BP or pre-eclampsia. They felt able to incorporate self-monitoring into their weekly routines, although this was harder post-partum. Self-monitoring of BP made them more aware of the risks of hypertension and pre-eclampsia in pregnancy. Feelings of reassurance and empowerment were commonly reported by the women in our sample. SMBP in pregnancy was both acceptable and feasible to women in this small pilot study.

Evaluation of the Effect of Silicone Contamination on Various Bond Systems and the Feasibility of Removing the Contamination

NASA Technical Reports Server (NTRS)

Stanley, Stephanie D.

2008-01-01

Silicone is a contaminant that can cause catastrophic failure of a bond system depending on the materials and processes used to fabricate the bond system, Unfortunately, more and more materials are fabricated using silicone. The purpose of this testing was to evaluate which bond systems are sensitive to silicone contamination and whether or not a cleaning process could be utilized to remove the silicone to bring the bond system performance back to baseline. Due to the extensive nature of the testing attempts will be made to generalize the understanding within classes of substrates, bond systems, and surface preparation and cleaning methods. This study was done by contaminating various meta! (steel, inconel, and aluminum), phenolic (carbon cloth phenolic and glass cloth phenolic), and rubber (natural rubber, asbestos-silicone dioxide filled natural butyldiene rubber, silica-filled ethylene propylenediene monomer, and carbon-filled ethylene propylenediene monomer) substrates which were then bonded using various adhesives and coatings (epoxy-based adhesives, paints, ablative compounds, and Chemlok adhesives) to determine the effect silicone contamination has on a given bond system's performance. The test configurations depended on the bond system being evaluated. The study also evaluated the feasibility of removing the silicone contamination by cleaning the contaminated substrate prior to bonding. The cleaning processes also varied depending on bond system.

Albion: the UK 3rd generation high-performance thermal imaging programme

NASA Astrophysics Data System (ADS)

McEwen, R. K.; Lupton, M.; Lawrence, M.; Knowles, P.; Wilson, M.; Dennis, P. N. J.; Gordon, N. T.; Lees, D. J.; Parsons, J. F.

2007-04-01

The first generation of high performance thermal imaging sensors in the UK was based on two axis opto-mechanical scanning systems and small (4-16 element) arrays of the SPRITE detector, developed during the 1970s. Almost two decades later, a 2nd Generation system, STAIRS C was introduced, based on single axis scanning and a long linear array of approximately 3000 elements. The UK has now begun the industrialisation of 3 rd Generation High Performance Thermal Imaging under a programme known as "Albion". Three new high performance cadmium mercury telluride arrays are being manufactured. The CMT material is grown by MOVPE on low cost substrates and bump bonded to the silicon read out circuit (ROIC). To maintain low production costs, all three detectors are designed to fit with existing standard Integrated Detector Cooling Assemblies (IDCAs). The two largest focal planes are conventional devices operating in the MWIR and LWIR spectral bands. A smaller format LWIR device is also described which has a smart ROIC, enabling much longer stare times than are feasible with conventional pixel circuits, thus achieving very high sensitivity. A new reference surface technology for thermal imaging sensors is described, based on Negative Luminescence (NL), which offers several advantages over conventional peltier references, improving the quality of the Non-Uniformity Correction (NUC) algorithms.

IRAC test report. Gallium doped silicon band 2: Read noise and dark current

NASA Technical Reports Server (NTRS)

Lamb, Gerald; Shu, Peter; Mather, John; Ewin, Audrey; Bowser, Jeffrey

1987-01-01

A direct readout infrared detector array, a candidate for the Space Infrared Telescope Facility (SIRTF) Infrared Array Camera (IRAC), has been tested. The array has a detector surface of gallium doped silicon, bump bonded to a 58x62 pixel MOSFET multiplexer on a separate chip. Although this chip and system do not meet all the SIRTF requirements, the critically important read noise is within a factor of 3 of the requirement. Significant accomplishments of this study include: (1) development of a low noise correlated double sampling readout system with a readout noise of 127 to 164 electrons (based on the detector integrator capacitance of 0.1 pF); (2) measurement of the readout noise of the detector itself, ranging from 123 to 214 electrons with bias only (best to worst pixel), and 256 to 424 electrons with full clocking in normal operation at 5.4 K where dark current is small. Thirty percent smaller read noises are obtained at a temperature of 15K; (3) measurement of the detector response versus integration time, showing significant nonlinear behavior for large signals, well below the saturation level; and (4) development of a custom computer interface and suitable software for collection, analysis and display of data.

Development of 4-Sides Buttable CdTe-ASIC Hybrid Module for X-ray Flat Panel Detector

NASA Astrophysics Data System (ADS)

Tamaki, Mitsuru; Mito, Yoshio; Shuto, Yasuhiro; Kiyuna, Tatsuya; Yamamoto, Masaya; Sagae, Kenichi; Kina, Tooru; Koizumi, Tatsuhiro; Ohno, Ryoichi

2009-08-01

A 4-sides buttable CdTe-ASIC hybrid module suitable for use in an X-ray flat panel detector (FPD) has been developed by applying through silicon via (TSV) technology to the readout ASIC. The ASIC has 128 times 256 channels of charge integration type readout circuitry and an area of 12.9 mm times 25.7 mm. The CdTe sensor of 1 mm thickness, having the same area and pixel of 100 mum pitch, was fabricated from the Cl-doped CdTe single crystal grown by traveling heater method (THM). Then the CdTe pixel sensor was hybridized with the ASIC using the bump-bonding technology. The basic performance of this 4-sides buttable module was evaluated by taking X-ray images, and it was compared with that of a commercially available indirect type CsI(Tl) FPD. A prototype CdTe FPD was made by assembling 9 pieces of the 4-sides buttable modules into 3 times 3 arrays in which the neighboring modules were mounted on the interface board. The FPD covers an active area of 77 mm times 39 mm. The results showed the great potential of this 4-sides buttable module for the new real time X-ray FPD with high spatial resolution.

Ball-grid array architecture for microfabricated ion traps

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

Guise, Nicholas D., E-mail: nicholas.guise@gtri.gatech.edu; Fallek, Spencer D.; Stevens, Kelly E.

2015-05-07

State-of-the-art microfabricated ion traps for quantum information research are approaching nearly one hundred control electrodes. We report here on the development and testing of a new architecture for microfabricated ion traps, built around ball-grid array (BGA) connections, that is suitable for increasingly complex trap designs. In the BGA trap, through-substrate vias bring electrical signals from the back side of the trap die to the surface trap structure on the top side. Gold-ball bump bonds connect the back side of the trap die to an interposer for signal routing from the carrier. Trench capacitors fabricated into the trap die replace area-intensivemore » surface or edge capacitors. Wirebonds in the BGA architecture are moved to the interposer. These last two features allow the trap die to be reduced to only the area required to produce trapping fields. The smaller trap dimensions allow tight focusing of an addressing laser beam for fast single-qubit rotations. Performance of the BGA trap as characterized with {sup 40}Ca{sup +} ions is comparable to previous surface-electrode traps in terms of ion heating rate, mode frequency stability, and storage lifetime. We demonstrate two-qubit entanglement operations with {sup 171}Yb{sup +} ions in a second BGA trap.« less

Performance of a 512 x 512 Gated CMOS Imager with a 250 ps Exposure Time

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

Teruya, A T; Moody, J D; Hsing, W W

2012-10-01

We describe the performance of a 512x512 gated CMOS read out integrated circuit (ROIC) with a 250 ps exposure time. A low-skew, H-tree trigger distribution system is used to locally generate individual pixel gates in each 8x8 neighborhood of the ROIC. The temporal width of the gate is voltage controlled and user selectable via a precision potentiometer. The gating implementation was first validated in optical tests of a 64x64 pixel prototype ROIC developed as a proof-of-concept during the early phases of the development program. The layout of the H-Tree addresses each quadrant of the ROIC independently and admits operation ofmore » the ROIC in two modes. If “common mode” triggering is used, the camera provides a single 512x512 image. If independent triggers are used, the camera can provide up to four 256x256 images with a frame separation set by the trigger intervals. The ROIC design includes small (sub-pixel) optical photodiode structures to allow test and characterization of the ROIC using optical sources prior to bump bonding. Reported test results were obtained using short pulse, second harmonic Ti:Sapphire laser systems operating at λ~ 400 nm at sub-ps pulse widths.« less

Characterization of Kilopixel TES detector arrays for PIPER

NASA Astrophysics Data System (ADS)

Datta, Rahul; Ade, Peter; Benford, Dominic; Bennett, Charles; Chuss, David; Costen, Nicholas; Coughlin, Kevin; Dotson, Jessie; Eimer, Joseph; Fixsen, Dale; Gandilo, Natalie; Halpern, Mark; Essinger-Hileman, Thomas; Hilton, Gene; Hinshaw, Gary; Irwin, Kent; Jhabvala, Christine; Kimball, Mark; Kogut, Al; Lazear, Justin; Lowe, Luke; Manos, George; McMahon, Jeff; Miller, Timothy; Mirel, Paul; Moseley, Samuel Harvey; Pawlyk, Samuel; Rodriguez, Samelys; Sharp, Elmer; Shirron, Peter; Staguhn, Johannes G.; Sullivan, Dan; Switzer, Eric; Taraschi, Peter; Tucker, Carole; Walts, Alexander; Wollack, Edward

2018-01-01

The Primordial Inflation Polarization ExploreR (PIPER) is a balloon-borne instrument optimized to measure the polarization of the Cosmic Microwave Background (CMB) at large angular scales. It will map 85% of the sky in four frequency bands centered at 200, 270, 350, and 600 GHz to characterize dust foregrounds and constrain the tensor-to-scalar ratio, r. The sky is imaged on to 32x40 pixel arrays of time-domain multiplexed Transition-Edge Sensor (TES) bolometers operating at a bath temperature of 100 mK to achieve background-limited sensitivity. Each kilopixel array is indium-bump-bonded to a 2D superconducting quantum interference device (SQUID) time-domain multiplexer (MUX) chip and read out by warm electronics. Each pixel measures total incident power over a frequency band defined by bandpass filters in front of the array, while polarization sensitivity is provided by the upstream Variable-delay Polarization Modulators (VPMs) and analyzer grids. We present measurements of the detector parameters from the laboratory characterization of the first kilopixel science array for PIPER including transition temperature, saturation power, thermal conductivity, time constant, and noise performance. We also describe the testing of the 2D MUX chips, optimization of the integrated readout parameters, and the overall pixel yield of the array. The first PIPER science flight is planned for June 2018 from Palestine, Texas.

Radiation hardness and timing studies of a monolithic TowerJazz pixel design for the new ATLAS Inner Tracker

NASA Astrophysics Data System (ADS)

Riegel, C.; Backhaus, M.; Van Hoorne, J. W.; Kugathasan, T.; Musa, L.; Pernegger, H.; Riedler, P.; Schaefer, D.; Snoeys, W.; Wagner, W.

2017-01-01

A part of the upcoming HL-LHC upgrade of the ATLAS Detector is the construction of a new Inner Tracker. This upgrade opens new possibilities, but also presents challenges in terms of occupancy and radiation tolerance. For the pixel detector inside the inner tracker, hybrid modules containing passive silicon sensors and connected readout chips are presently used, but require expensive assembly techniques like fine-pitch bump bonding. Silicon devices fabricated in standard commercial CMOS technologies, which include part or all of the readout chain, are also investigated offering a reduced cost as they are cheaper per unit area than traditional silicon detectors. If they contain the full readout chain, as for a fully monolithic approach, there is no need for the expensive flip-chip assembly, resulting in a further cost reduction and material savings. In the outer pixel layers of the ATLAS Inner Tracker, the pixel sensors must withstand non-ionising energy losses of up to 1015 n/cm2 and offer a timing resolution of 25 ns or less. This paper presents test results obtained on a monolithic test chip, the TowerJazz 180nm Investigator, towards these specifications. The presented program of radiation hardness and timing studies has been launched to investigate this technology's potential for the new ATLAS Inner Tracker.

A panoramic coded aperture gamma camera for radioactive hotspots localization

NASA Astrophysics Data System (ADS)

Paradiso, V.; Amgarou, K.; Blanc De Lanaute, N.; Schoepff, V.; Amoyal, G.; Mahe, C.; Beltramello, O.; Liénard, E.

2017-11-01

A known disadvantage of the coded aperture imaging approach is its limited field-of-view (FOV), which often results insufficient when analysing complex dismantling scenes such as post-accidental scenarios, where multiple measurements are needed to fully characterize the scene. In order to overcome this limitation, a panoramic coded aperture γ-camera prototype has been developed. The system is based on a 1 mm thick CdTe detector directly bump-bonded to a Timepix readout chip, developed by the Medipix2 collaboration (256 × 256 pixels, 55 μm pitch, 14.08 × 14.08 mm2 sensitive area). A MURA pattern coded aperture is used, allowing for background subtraction without the use of heavy shielding. Such system is then combined with a USB color camera. The output of each measurement is a semi-spherical image covering a FOV of 360 degrees horizontally and 80 degrees vertically, rendered in spherical coordinates (θ,phi). The geometrical shapes of the radiation-emitting objects are preserved by first registering and stitching the optical images captured by the prototype, and applying, subsequently, the same transformations to their corresponding radiation images. Panoramic gamma images generated by using the technique proposed in this paper are described and discussed, along with the main experimental results obtained in laboratories campaigns.

Low-temperature direct bonding of glass nanofluidic chips using a two-step plasma surface activation process.

PubMed

Xu, Yan; Wang, Chenxi; Dong, Yiyang; Li, Lixiao; Jang, Kihoon; Mawatari, Kazuma; Suga, Tadatomo; Kitamori, Takehiko

2012-01-01

Owing to the well-established nanochannel fabrication technology in 2D nanoscales with high resolution, reproducibility, and flexibility, glass is the leading, ideal, and unsubstitutable material for the fabrication of nanofluidic chips. However, high temperature (~1,000 °C) and a vacuum condition are usually required in the conventional fusion bonding process, unfortunately impeding the nanofluidic applications and even the development of the whole field of nanofluidics. We present a direct bonding of fused silica glass nanofluidic chips at low temperature, around 200 °C in ambient air, through a two-step plasma surface activation process which consists of an O(2) reactive ion etching plasma treatment followed by a nitrogen microwave radical activation. The low-temperature bonded glass nanofluidic chips not only had high bonding strength but also could work continuously without leakage during liquid introduction driven by air pressure even at 450 kPa, a very high pressure which can meet the requirements of most nanofluidic operations. Owing to the mild conditions required in the bonding process, the method has the potential to allow the integration of a range of functional elements into nanofluidic chips during manufacture, which is nearly impossible in the conventional high-temperature fusion bonding process. Therefore, we believe that the developed low-temperature bonding would be very useful and contribute to the field of nanofluidics.

Aeroflex Technology as Class-Y Demonstrator

NASA Technical Reports Server (NTRS)

Suh, Jong-ook; Agarwal, Shri; Popelar, Scott

2014-01-01

Modern space field programmable gate array (FPGA) devices with increased functional density and operational frequency, such as Xilinx Virtex 4 (V4) and S (V5), are packaged in non-hermetic ceramic flip chip forms. These next generation space parts were not qualified to the MIL-PRF-38535 Qualified Manufacturer Listing (QML) class-V when they were released because class-V was only intended for hermetic parts. In order to bring Xilinx V5 type packages into the QML system, it was suggested that class-Y be set up as a new category. From 2010 through 2014, a JEDEC G12 task group developed screening and qualification requirements for Class-Y products. The Document Standardization Division of the Defense Logistics Agency (DLA) has completed an engineering practice study. In parallel with the class-Y efforts, the NASA Electronic Parts and Packaging (NEPP) program has funded JPL to study potential reliability issues of the class-Y products. The major hurdle of this task was the absence of adequate research samples. Figure 1-1 shows schematic diagrams of typical structures of class-Y type products. Typically, class-Y products are either in ceramic flip chip column grid array (CGA) or land grid array (LGA) form. In class-Y packages, underfill and heat spread adhesive materials are directly exposed to the spacecraft environment due to their non-hermeticity. One of the concerns originally raised was that the underfill material could degrade due to the spacecraft environment and negatively impact the reliability of the package. In order to study such issues, it was necessary to use ceramic daisy chain flip chip package samples so that continuity of flip chip solder bumps could be monitored during the reliability tests. However, none of the commercially available class-Y daisy chain parts had electrical connections through flip chip solder bumps; only solder columns were daisy chained, which made it impossible to test continuity of flip chip solder bumps without using extremely costly functional parts. Among space parts manufacturers who were interested in producing class-Y products, Aeroflex Microelectronic Solutions-HiRel had been developing assembly processes using their internal R&D classy type samples. In early 2012, JPL and Aeroflex initiated a collaboration to study reliability of the Aeroflex technology as a class-Y demonstrator.

What can we learn from "internal plateaus"? The peculiar afterglow of GRB 070110

NASA Astrophysics Data System (ADS)

Beniamini, P.; Mochkovitch, R.

2017-09-01

Context. The origin of the prompt emission of gamma-ray bursts is highly debated. Proposed scenarios involve various dissipation processes (shocks, magnetic reconnection, and inelastic collisions) above or below the photosphere of an ultra-relativistic outflow. Aims: We search for observational features that could help to favour one scenario over the others by constraining the dissipation radius, the magnetization of the outflow, or by indicating the presence of shocks. Bursts showing peculiar behaviours can emphasize the role of a specific physical ingredient, which becomes more apparent under certain circumstances. Methods: We study GRB 070110, which exhibited several remarkable features during its early afterglow; I.e. a very flat plateau terminated by an extremely steep drop and immediately followed by a bump. We modelled the plateau as the photospheric emission from a long-lasting outflow of moderate Lorentz factor (Γ 20), which lags behind an ultra-relativistic (Γ > 100) ejecta that is responsible for the prompt emission. We computed the dissipation of energy in the forward and reverse shocks resulting from the deceleration of this ejecta by the external medium (uniform or stellar wind). Results: We find that photospheric emission from the long-lasting outflow can account for the plateau properties (luminosity and spectrum) assuming that some dissipation takes place in the flow. The geometrical timescale at the photospheric radius is so short that the observed decline at the end of the plateau likely corresponds to the actual shutdown of the activity in the central engine. The bump that follows results from the power dissipated in the reverse shock, which develops when the material making the plateau catches up with the initially fast shell in front, after the fast shell has decelerated. Conclusions: The proposed interpretation suggests that the prompt phase results from dissipation above the photosphere while the plateau has a photospheric origin. If the bump is produced by the reverse shock, it implies an upper limit (σ ≲ 0.1) on the magnetization of the low Γ material making the plateau. A plateau that is terminated by a drop as steep as in GRB 070110 was not observed in any other long burst. It could mean that persistent outflows are very uncommon or that the plateau luminosity or the energy of the emitted photons are generally much lower because the outflow remains mostly adiabatic or has a Lorentz factor below 10.

BEAMLINE-CONTROLLED STEERING OF SOURCE-POINT ANGLE AT THE ADVANCED PHOTON SOURCE

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

Emery, L.; Fystro, G.; Shang, H.

An EPICS-based steering software system has been implemented for beamline personnel to directly steer the angle of the synchrotron radiation sources at the Advanced Photon Source. A script running on a workstation monitors "start steering" beamline EPICS records, and effects a steering given by the value of the "angle request" EPICS record. The new system makes the steering process much faster than before, although the older steering protocols can still be used. The robustness features of the original steering remain. Feedback messages are provided to the beamlines and the accelerator operators. Underpinning this new steering protocol is the recent refinementmore » of the global orbit feedback process whereby feedforward of dipole corrector set points and orbit set points are used to create a local steering bump in a rapid and seamless way.« less

Modeling of direct wafer bonding: Effect of wafer bow and etch patterns

NASA Astrophysics Data System (ADS)

Turner, K. T.; Spearing, S. M.

2002-12-01

Direct wafer bonding is an important technology for the manufacture of silicon-on-insulator substrates and microelectromechanical systems. As devices become more complex and require the bonding of multiple patterned wafers, there is a need to understand the mechanics of the bonding process. A general bonding criterion based on the competition between the strain energy accumulated in the wafers and the surface energy that is dissipated as the bond front advances is developed. The bonding criterion is used to examine the case of bonding bowed wafers. An analytical expression for the strain energy accumulation rate, which is the quantity that controls bonding, and the final curvature of a bonded stack is developed. It is demonstrated that the thickness of the wafers plays a large role and bonding success is independent of wafer diameter. The analytical results are verified through a finite element model and a general method for implementing the bonding criterion numerically is presented. The bonding criterion developed permits the effect of etched features to be assessed. Shallow etched patterns are shown to make bonding more difficult, while it is demonstrated that deep etched features can facilitate bonding. Model results and their process design implications are discussed in detail.

Traumatic Brain Injury (TBI) in Kids

MedlinePlus

... Information Share Facebook Twitter Pinterest Email Print Traumatic Brain Injury (TBI): Condition Information What is TBI? TBI ... external force that affects the functioning of the brain. It can be caused by a bump or ...

Poison Ivy/Oak/Sumac

MedlinePlus

... burning, or blistering. Severe, widespread rashes require medical treatment. Signs and Symptoms an itchy red rash that appears within 4 hours to 4 days after touching the plant oil blisters that ooze clear fluid bumps and ...

Traumatic Brain Injury

MedlinePlus

Traumatic brain injury (TBI) happens when a bump, blow, jolt, or other head injury causes damage to the brain. Every year, millions of people in the U.S. suffer brain injuries. More than half are bad enough that ...

AC orbit bump method of local impedance measurement

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

Smaluk, Victor; Yang, Xi; Blednykh, Alexei

A fast and precise technique of local impedance measurement has been developed and tested at NSLS-II. This technique is based on in-phase sine-wave (AC) excitation of four fast correctors adjacent to the vacuum chamber section, impedance of which is measured. The beam position is measured using synchronous detection. Use of the narrow-band sine-wave signal allows us to improve significantly the accuracy of the orbit bump method. Beam excitation by fast correctors results in elimination of the systematic error caused by hysteresis effect. The systematic error caused by orbit drift is also eliminated because the measured signal is not affected bymore » the orbit motion outside the excitation frequency range. In this article, the measurement technique is described and the result of proof-of-principle experiment carried out at NSLS-II is presented.« less

Equations of motion of the lunar roving vehicle.

NASA Technical Reports Server (NTRS)

Kaufman, S.

1973-01-01

Equations of motion have been formulated for a four-wheel vehicle as it traverses a terrain characterized by slopes, craters, bumps, washboards, or a power spectrum. Independent suspension and electric motor propulsion are considered. These equations were programmed on the UNIVAC 1108 digital computer. Results are given for the steerability of the Lunar Roving Vehicle (LRV) which was found to be satisfactory for normal operating speeds and turning radii. The vehicle was also found to be satisfactory against overturning in both the pitch and roll mode, and results are presented for various speeds as the LRV engages a bump on meter in diameter and of varying heights. Speed, power consumption, and load characteristics are presented for the LRV traversing a simulated lunar soil at full throttle. Comparisons are given against data compiled from the Apollo 15 mission.

AC orbit bump method of local impedance measurement

DOE PAGES

Smaluk, Victor; Yang, Xi; Blednykh, Alexei; ...

2017-08-04

A fast and precise technique of local impedance measurement has been developed and tested at NSLS-II. This technique is based on in-phase sine-wave (AC) excitation of four fast correctors adjacent to the vacuum chamber section, impedance of which is measured. The beam position is measured using synchronous detection. Use of the narrow-band sine-wave signal allows us to improve significantly the accuracy of the orbit bump method. Beam excitation by fast correctors results in elimination of the systematic error caused by hysteresis effect. The systematic error caused by orbit drift is also eliminated because the measured signal is not affected bymore » the orbit motion outside the excitation frequency range. In this article, the measurement technique is described and the result of proof-of-principle experiment carried out at NSLS-II is presented.« less

SHARDS: constraints on the dust attenuation law of star-forming galaxies at z ˜ 2

NASA Astrophysics Data System (ADS)

Tress, Mónica; Mármol-Queraltó, Esther; Ferreras, Ignacio; Pérez-González, Pablo G.; Barro, Guillermo; Pampliega, Belén Alcalde; Cava, Antonio; Domínguez-Sánchez, Helena; Eliche-Moral, Carmen; Espino-Briones, Néstor; Esquej, Pilar; Hernán-Caballero, Antonio; Rodighiero, Giulia; Rodriguez-Muñoz, Lucía

2018-04-01

We make use of the Survey of High-z Absorption Red and Dead Sources, an ultradeep (<26.5AB) galaxy survey that provides optical photospectra at resolution R ˜ 50, via medium-band filters (FWHM ˜ 150 Å). This data set is combined with ancillary optical and NIR fluxes to constrain the dust attenuation law in the rest-frame NUV region of star-forming galaxies within the redshift window 1.5 < z < 3. We focus on the NUV bump strength (B) and the total-to-selective extinction ratio (RV), targeting a sample of 1753 galaxies. By comparing the data with a set of population synthesis models coupled to a parametric dust attenuation law, we constrain RV and B, as well as the colour excess, E(B - V). We find a correlation between RV and B, which can be interpreted either as a result of the grain size distribution, or a variation of the dust geometry among galaxies. According to the former, small dust grains are associated with a stronger NUV bump. The latter would lead to a range of clumpiness in the distribution of dust within the interstellar medium of star-forming galaxies. The observed wide range of NUV bump strengths can lead to a systematic in the interpretation of the UV slope β typically used to characterize the dust content. In this study, we quantify these variations, concluding that the effects are Δβ ˜ 0.4.

Reconstruction of primordial tensor power spectra from B -mode polarization of the cosmic microwave background

NASA Astrophysics Data System (ADS)

Hiramatsu, Takashi; Komatsu, Eiichiro; Hazumi, Masashi; Sasaki, Misao

2018-06-01

Given observations of the B -mode polarization power spectrum of the cosmic microwave background (CMB), we can reconstruct power spectra of primordial tensor modes from the early Universe without assuming their functional form such as a power-law spectrum. The shape of the reconstructed spectra can then be used to probe the origin of tensor modes in a model-independent manner. We use the Fisher matrix to calculate the covariance matrix of tensor power spectra reconstructed in bins. We find that the power spectra are best reconstructed at wave numbers in the vicinity of k ≈6 ×10-4 and 5 ×10-3 Mpc-1 , which correspond to the "reionization bump" at ℓ≲6 and "recombination bump" at ℓ≈80 of the CMB B -mode power spectrum, respectively. The error bar between these two wave numbers is larger because of the lack of the signal between the reionization and recombination bumps. The error bars increase sharply toward smaller (larger) wave numbers because of the cosmic variance (CMB lensing and instrumental noise). To demonstrate the utility of the reconstructed power spectra, we investigate whether we can distinguish between various sources of tensor modes including those from the vacuum metric fluctuation and SU(2) gauge fields during single-field slow-roll inflation, open inflation, and massive gravity inflation. The results depend on the model parameters, but we find that future CMB experiments are sensitive to differences in these models. We make our calculation tool available online.

Fluxless eutectic bonding of GaAs-on-Si by using Ag/Sn solder

NASA Astrophysics Data System (ADS)

Eo, Sung-Hwa; Kim, Dae-Seon; Jeong, Ho-Jung; Jang, Jae-Hyung

2013-11-01

Fluxless GaAs-on-Si wafer bonding using Ag/Sn solder was investigated to realize uniform and void-free heterogeneous material integration. The effects of the diffusion barrier, Ag/Sn thickness, and Ar plasma treatment were studied to achieve the optimal fluxless bonding process. Pt on a GaAs wafer and Mo on a Si wafer act as diffusion barriers by preventing the flow of Ag/Sn solder into both the wafers. The bonding strength is closely related to the Ag/Sn thickness and Ar plasma treatment. A shear strength test was carried out to investigate the bonding strength. Under identical bonding conditions, the Ag/Sn thickness was optimized to achieve higher bonding strength and to avoid the formation of voids due to thermal stress. An Ar plasma pretreatment process improved the bonding strength because the Ar plasma removed carbon contaminants and metal-oxide bonds from the metal surface.

Integral glass encapsulation for solar arrays

NASA Technical Reports Server (NTRS)

Landis, G. A.

1981-01-01

Electrostatic bonding technology, an encapsulation technique for terrestrial solar array was developed. The process produces full integral, hermetic bonds with no adhesives or pottants. Panels of six solar cells on a simple glass superstrate were produced. Electrostatic bonding for making the cell front contact was also developed. A metal mesh is trapped into contact with the cell front during the bonding process. Six cell panels using the bonded mesh as the only cell front contact were produced. The possibility of using lower cost glass, with a higher thermal expansion mismatch to silicon, by making lower temperature bonds is developed. However, this requires a planar surface cell.

Solder extrusion pressure bonding process and bonded products produced thereby

DOEpatents

Beavis, Leonard C.; Karnowsky, Maurice M.; Yost, Frederick G.

1992-01-01

Production of soldered joints which are highly reliable and capable of surviving 10,000 thermal cycles between about -40.degree. C. and 110.degree. C. Process involves interposing a thin layer of a metal solder composition between the metal surfaces of members to be bonded and applying heat and up to about 1000 psi compression pressure to the superposed members, in the presence of a reducing atmosphere, to extrude the major amount of the solder composition, contaminants including fluxing gases and air, from between the members being bonded, to form a very thin, strong intermetallic bonding layer having a thermal expansion tolerant with that of the bonded members.

Solder extrusion pressure bonding process and bonded products produced thereby

NASA Astrophysics Data System (ADS)

Beavis, L. C.; Karnowsky, M. M.; Yost, F. G.

1990-04-01

The production of soldered joints are highly reliable and capable of surviving 10,000 thermal cycles between about -40 and 110 C. The process involves interposing a thin layer of a metal solder composition between the metal surfaces of members to be bonded and applying heat up to about 1000 psi compression pressure to the superposed members, in the presence of a reducing atmosphere, to extrude the major amount of the solder composition, contaminants including fluxing gases and air, from between the members being bonded, to form a very thin, strong intermetallic bonding layer having a thermal expansion tolerant with that of the bonded members.

Fabrication of five-level ultraplanar micromirror arrays by flip-chip assembly

NASA Astrophysics Data System (ADS)

Michalicek, M. Adrian; Bright, Victor M.

2001-10-01

This paper reports a detailed study of the fabrication of various piston, torsion, and cantilever style micromirror arrays using a novel, simple, and inexpensive flip-chip assembly technique. Several rectangular and polar arrays were commercially prefabricated in the MUMPs process and then flip-chip bonded to form advanced micromirror arrays where adverse effects typically associated with surface micromachining were removed. These arrays were bonded by directly fusing the MUMPs gold layers with no complex preprocessing. The modules were assembled using a computer-controlled, custom-built flip-chip bonding machine. Topographically opposed bond pads were designed to correct for slight misalignment errors during bonding and typically result in less than 2 micrometers of lateral alignment error. Although flip-chip micromirror performance is briefly discussed, the means used to create these arrays is the focus of the paper. A detailed study of flip-chip process yield is presented which describes the primary failure mechanisms for flip-chip bonding. Studies of alignment tolerance, bonding force, stress concentration, module planarity, bonding machine calibration techniques, prefabrication errors, and release procedures are presented in relation to specific observations in process yield. Ultimately, the standard thermo-compression flip-chip assembly process remains a viable technique to develop highly complex prototypes of advanced micromirror arrays.

Gamma-insensitive optical sensor

DOEpatents

Kruger, Hans W.

1994-01-01

An ultra-violet/visible/infra-red gamma-insensitive gas avalanche focal plane array comprising a planar photocathode and a planar anode pad array separated by a gas-filled gap and across which is applied an electric potential. Electrons ejected from the photocathode are accelerated sufficiently between collisions with the gas molecules to ionize them, forming an electron avalanche. The gap acts like a proportional counter. The array of anode pad are mounted on the front of an anode plate and are connected to matching contact pads on the back of the anode via feed through wires. Connection of the anode to signal processing electronics is made from the contact pads using standard indium bump techniques, for example.

Terahertz carpet cloak based on ultrathin metasurface

NASA Astrophysics Data System (ADS)

Wei, Minggui; Yang, Quanlong; Zhang, Xueqian; Li, Yanfeng; Gu, Jianqiang; Han, Jiaguang; Zhang, Weili

2018-01-01

Ultrathin metasurfaces with local phase compensation deliver new schemes to cloaking devices. We demonstrate a remarkable large size carpet cloak realized by an ultrathin metasurface at terahertz frequencies. The metasurface cloak is constructed by periodically arranging 12 different elements. The reflected wave front is perfectly reconstructed by an ultrathin metasurface cloak, which perform well under both intensity-sensitive and phase-sensitive detectors. The invisibility is verified when the cloak is placed on a reflecting triangular surface (bump). The multi-step discrete phase design method would greatly simplify the design process and is probable to achieve large-dimension cloaks, for applications in radar and antenna systems as a thin and easy-to-fabricate solution for radio and terahertz frequencies.

Bond layer for a solid oxide fuel cell, and related processes and devices

DOEpatents

Wu, Jian; Striker, Todd-Michael; Renou, Stephane; Gaunt, Simon William

2017-03-21

An electrically-conductive layer of material having a composition comprising lanthanum and strontium is described. The material is characterized by a microstructure having bimodal porosity. Another concept in this disclosure relates to a solid oxide fuel cell attached to at least one cathode interconnect by a cathode bond layer. The bond layer includes a microstructure having bimodal porosity. A fuel cell stack which incorporates at least one of the cathode bond layers is also described herein, along with related processes for forming the cathode bond layer.

A crunch on thermocompression flip chip bonding

NASA Astrophysics Data System (ADS)

Suppiah, Sarveshvaran; Ong, Nestor Rubio; Sauli, Zaliman; Sarukunaselan, Karunavani; Alcain, Jesselyn Barro; Mahmed, Norsuria; Retnasamy, Vithyacharan

2017-09-01

This study discussed the evolution and important findings, critical technical challenges, solutions and bonding equipment of flip chip thermo compression bonding (TCB). The bonding force, temperature and time were the key bonding parameters that need to be tweaked based on the researches done by others. TCB technology worked well with both pre-applied underfill and flux (still under development). Lower throughput coupled with higher processing costs was example of challenges in the TCB technology. The paper is concluded with a brief description of the current equipment used in thermo compression process.

Evaluation of the Effect of Silicone Contamination on Various Bond Systems and the Feasibility of Removing the Contamination

NASA Technical Reports Server (NTRS)

Stanley, Stephanie D.

2008-01-01

Silicone is a contaminant that can cause catastrophic failure of a bond system depending on the materials and processes used to fabricate the bond system. Unfortunately, more and more materials are fabricated using silicone. The purpose of this testing was to evaluate which bond systems are sensitive to silicone contamination and whether or not a cleaning process could be utilized to remove the silicone to bring the bond system performance back to baseline. Due to the extensive nature of the testing, attempts will be made to generalize the understanding within classes of substrates, bond systems, and surface preparation and cleaning methods. This study was done by contaminating various metal (steel, Inconel, and aluminum), phenolic (carbon-cloth phenolic [CCP] and glass-cloth phenolic [GCP]), and rubber (natural rubber, asbestos-silicone dioxide filled natural butyldiene rubber [ASNBR]; silica-filled ethylene propylenediene monomer [SFEPDM], and carbon-filled ethylene propylenediene monomer [CFEPDM]) substrates which were then bonded using various adhesives and coatings (epoxy-based adhesives, paints, ablative compounds, and Chemlok adhesives) to determine the effect silicone contamination has on a given bond system's performance. The test configurations depended on the bond system being evaluated. The study also evaluated the feasibility of removing the silicone contamination by cleaning the contaminated substrate prior to bonding. The cleaning processes also varied depending on bond system.

Partial Transient Liquid-Phase Bonding, Part II: A Filtering Routine for Determining All Possible Interlayer Combinations

NASA Astrophysics Data System (ADS)

Cook, Grant O.; Sorensen, Carl D.

2013-12-01

Partial transient liquid-phase (PTLP) bonding is currently an esoteric joining process with limited applications. However, it has preferable advantages compared with typical joining techniques and is the best joining technique for certain applications. Specifically, it can bond hard-to-join materials as well as dissimilar material types, and bonding is performed at comparatively low temperatures. Part of the difficulty in applying PTLP bonding is finding suitable interlayer combinations (ICs). A novel interlayer selection procedure has been developed to facilitate the identification of ICs that will create successful PTLP bonds and is explained in a companion article. An integral part of the selection procedure is a filtering routine that identifies all possible ICs for a given application. This routine utilizes a set of customizable parameters that are based on key characteristics of PTLP bonding. These parameters include important design considerations such as bonding temperature, target remelting temperature, bond solid type, and interlayer thicknesses. The output from this routine provides a detailed view of each candidate IC along with a broad view of the entire candidate set, greatly facilitating the selection of ideal ICs. This routine provides a new perspective on the PTLP bonding process. In addition, the use of this routine, by way of the accompanying selection procedure, will expand PTLP bonding as a viable joining process.

Qualifying a Bonding Process for the Space Interferometry Mission

NASA Technical Reports Server (NTRS)

Joyce, Gretchen P.

2005-01-01

The Space Interferometry Mission consists of three parallel Michelson interferometers that will be capable of detecting extrasolar planets with a high degree of accuracy and precision. High levels of stability must be met in order to fulfill the scientific requirements of this mission. To attain successful measurements the coefficient of thermal expansion between optics and bonding material must be minimized without jeopardizing the integrity of the bonds. Optic-to-optic bonds have been analyzed to better understand variables such as the effects of the coefficient of thermal expansion differences between optics and bonding materials, and materials have been chosen for the project based on these analyses. A study was conducted to determine if a reliable, repeatable process for bonding by wicking adhesive could be obtained using a low-viscosity epoxy and ultra-low expansion glass. A process of creating a methodology of bonding fused silica optics with Z-6020 silane primer and Epo-Tek 301 epoxy will be discussed.

Large Area Active Brazing of Multi-tile Ceramic-Metal Structures

DTIC Science & Technology

2012-05-01

metallurgical bonds. The major disadvantage of using active brazing for metals and ceramics is the high processing temperature required that results in...steels) and form strong, metallurgical bonds. However, the high processing temperatures result in large strain (stress) build-up from the inherent...metals such as titanium alloys and stainless steels) and form strong, metallurgical bonds. However, the high processing temperatures result in large

Influence of the processing route of porcelain/Ti-6Al-4V interfaces on shear bond strength.

PubMed

Toptan, Fatih; Alves, Alexandra C; Henriques, Bruno; Souza, Júlio C M; Coelho, Rui; Silva, Filipe S; Rocha, Luís A; Ariza, Edith

2013-04-01

This study aims at evaluating the two-fold effect of initial surface conditions and dental porcelain-to-Ti-6Al-4V alloy joining processing route on the shear bond strength. Porcelain-to-Ti-6Al-4V samples were processed by conventional furnace firing (porcelain-fused-to-metal) and hot pressing. Prior to the processing, Ti-6Al-4V cylinders were prepared by three different surface treatments: polishing, alumina or silica blasting. Within the firing process, polished and alumina blasted samples were subjected to two different cooling rates: air cooling and a slower cooling rate (65°C/min). Metal/porcelain bond strength was evaluated by shear bond test. The data were analyzed using one-way ANOVA followed by Tuckey's test (p<0.05). Before and after shear bond tests, metallic surfaces and metal/ceramic interfaces were examined by Field Emission Gun Scanning Electron Microscope (FEG-SEM) equipped with Energy Dispersive X-Ray Spectroscopy (EDS). Shear bond strength values of the porcelain-to-Ti-6Al-4V alloy interfaces ranged from 27.1±8.9MPa for porcelain fused to polished samples up to 134.0±43.4MPa for porcelain fused to alumina blasted samples. According to the statistical analysis, no significant difference were found on the shear bond strength values for different cooling rates. Processing method was statistically significant only for the polished samples, and airborne particle abrasion was statistically significant only for the fired samples. The type of the blasting material did not cause a statistically significant difference on the shear bond strength values. Shear bond strength of dental porcelain to Ti-6Al-4V alloys can be significantly improved from controlled conditions of surface treatments and processing methods. Copyright © 2013 Elsevier Ltd. All rights reserved.

Cluster Headache

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... after a head injury, even if it's a minor fall or bump, especially if it worsens A sudden, severe headache unlike any you've had A headache that worsens over days and changes in pattern Causes The exact cause of cluster ...

Block the Buzzing, Bites, and Bumps: Preventing Mosquito-Borne Illnesses

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... Ten Mosquito Facts West Nile Virus Dengue Fever Malaria Zika Virus Infection Zika Virus Information and Resources References The live attenuated dengue vaccine TV003 elicits complete protection against dengue in a ...

Genetics Home Reference: autosomal recessive hypotrichosis

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... Autosomal recessive hypotrichosis is a condition that affects hair growth. People with this condition have sparse hair ( hypotrichosis ) ... erosions) on the scalp. In areas of poor hair growth, they may also develop bumps called hyperkeratotic follicular ...

Implementation impacts : volume 3, summer 2014.

DOT National Transportation Integrated Search

2014-01-01

Summary of research projects at the Louisiana Transportation Research Center. Projects in this issue include: Edge Lines Reduce the : Number of Crashes on : Rural Two-lane Highways; New Approach Slab Design Decreases Bridge Bumps : in the Road;...

Solid-Liquid Interdiffusion Bonding of Silicon Carbide to Steel for High Temperature MEMS Sensor Packaging and Bonding

NASA Astrophysics Data System (ADS)

Chan, Matthew Wei-Jen

Complex engineering systems ranging from automobile engines to geothermal wells require specialized sensors to monitor conditions such as pressure, acceleration and temperature in order to improve efficiency and monitor component lifetime in what may be high temperature, corrosive, harsh environments. Microelectromechanical systems (MEMS) have demonstrated their ability to precisely and accurately take measurements under such conditions. The systems being monitored are typically made from metals, such as steel, while the MEMS sensors used for monitoring are commonly fabricated from silicon, silicon carbide and aluminum nitride, and so there is a sizable thermal expansion mismatch between the two. For these engineering applications the direct bonding of MEMS sensors to the components being monitored is often required. This introduces several challenges, namely the development of a bond that is capable of surviving high temperature harsh environments while mitigating the thermally induced strains produced during bonding. This project investigates the development of a robust packaging and bonding process, using the gold-tin metal system and the solid-liquid interdiffusion (SLID) bonding process, to join silicon carbide substrates directly to type-316 stainless steel. The SLID process enables bonding at lower temperatures while producing a bond capable of surviving higher temperatures. Finite element analysis was performed to model the thermally induced strains generated in the bond and to understand the optimal way to design the bond. The cross-sectional composition of the bonds has been analyzed and the bond strength has been investigated using die shear testing. The effects of high temperature aging on the bond's strength and the metallurgy of the bond were studied. Additionally, loading of the bond was performed at temperatures over 415 °C, more than 100 °C, above the temperature used for bonding, with full survival of the bond, thus demonstrating the benefit of SLID bonding for high temperature applications. Lastly, this dissertation provides recommendations for improving the strength and durability of the bond at temperatures of 400 °C and provides the framework for future work in the area of high temperature harsh environment MEMS packaging that would take directly bonded MEMS to temperatures of 600 °C and beyond.

From magic to technology: materials integration by wafer bonding

NASA Astrophysics Data System (ADS)

Dragoi, Viorel

2006-02-01

Wafer bonding became in the last decade a very powerful technology for MEMS/MOEMS manufacturing. Being able to offer a solution to overcome some problems of the standard processes used for materials integration (e.g. epitaxy, thin films deposition), wafer bonding is nowadays considered an important item in the MEMS engineer toolbox. Different principles governing the wafer bonding processes will be reviewed in this paper. Various types of applications will be presented as examples.

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

Dickerson, Patricia O'Donnell; Summa, Deborah Ann; Liu, Cheng

The goals of this project were to demonstrate reliable, reproducible solid state bonding of aluminum 6061 alloy plates together to encapsulate DU-10 wt% Mo surrogate fuel foils. This was done as part of the CONVERT Fuel Fabrication Capability effort in Process Baseline Development . Bonding was done using Hot Isotatic Pressing (HIP) of evacuated stainless steel cans (a.k.a HIP cans) containing fuel plate components and strongbacks. Gross macroscopic measurements of HIP cans prior to HIP and after HIP were used as part of this demonstration, and were used to determine the accuracy of a finitie element model of the HIPmore » bonding process. The quality of the bonding was measured by controlled miniature bulge testing for Al-Al, Al-Zr, and Zr-DU bonds. A special objective was to determine if the HIP process consistently produces good quality bonding and to determine the best characterization techniques for technology transfer.« less

A static induction device manufactured by silicon direct bonding

NASA Astrophysics Data System (ADS)

Chen, Xin'an; Liu, Su; Huang, Qing'an

2004-07-01

It is always a key problem how to improve the gate-source breakdown voltage (VGK) of static induction devices during manufacturing. By using a silicon direct bonding process to replace the high resistivity epitaxy process, a bonding buried gate structure is formed, which is different from an epitaxy buried gate structure. The new structure can improve the gate-source breakdown voltage from the process and the structure. It is shown that the bonding buried gate structure is a promising structure, that can improve the VGK and other performances of devices, by manufacture of a static induction thyristor.

Fabrication of stainless steel clad tubing. [gas pressure bonding

NASA Technical Reports Server (NTRS)

Kovach, C. W.

1978-01-01

The feasibility of producing stainless steel clad carbon steel tubing by a gas pressure bonding process was evaluated. Such a tube product could provide substantial chromium savings over monolithic stainless tubing in the event of a serious chromium shortage. The process consists of the initial assembly of three component tubesets from conventionally produced tubing, the formation of a strong metallurgical bond between the three components by gas pressure bonding, and conventional cold draw and anneal processing to final size. The quality of the tubes produced was excellent from the standpoint of bond strength, mechanical, and forming properties. The only significant quality problem encountered was carburization of the stainless clad by the carbon steel core which can be overcome by further refinement through at least three different approaches. The estimated cost of clad tubing produced by this process is greater than that for monolithic stainless tubing, but not so high as to make the process impractical as a chromium conservation method.

Electron attachment-induced DNA single-strand breaks at the pyrimidine sites

PubMed Central

Gu, Jiande; Wang, Jing; Leszczynski, Jerzy

2010-01-01

To elucidate the contribution of pyrimidine in DNA strand breaks caused by low-energy electrons (LEEs), theoretical investigations of the LEE attachment-induced C3′–O3′, and C5′–O5′ σ bond as well as N-glycosidic bond breaking of 2′-deoxycytidine-3′,5′-diphosphate and 2′-deoxythymidine-3′,5′-diphosphate were performed using the B3LYP/DZP++ approach. The base-centered radical anions are electronically stable enough to assure that either the C–O or glycosidic bond breaking processes might compete with the electron detachment and yield corresponding radical fragments and anions. In the gas phase, the computed glycosidic bond breaking activation energy (24.1 kcal/mol) excludes the base release pathway. The low-energy barrier for the C3′–O3′ σ bond cleavage process (∼6.0 kcal/mol for both cytidine and thymidine) suggests that this reaction pathway is the most favorable one as compared to other possible pathways. On the other hand, the relatively low activation energy barrier (∼14 kcal/mol) for the C5′–O5′ σ bond cleavage process indicates that this bond breaking pathway could be possible, especially when the incident electrons have relatively high energy (a few electronvolts). The presence of the polarizable medium greatly increases the activation energies of either C–O σ bond cleavage processes or the N-glycosidic bond breaking process. The only possible pathway that dominates the LEE-induced DNA single strands in the presence of the polarizable surroundings (such as in an aqueous solution) is the C3′–O3′ σ bond cleavage (the relatively low activation energy barrier, ∼13.4 kcal/mol, has been predicted through a polarizable continuum model investigation). The qualitative agreement between the ratio for the bond breaks of C5′–O5′, C3′–O3′ and N-glycosidic bonds observed in the experiment of oligonucleotide tetramer CGAT and the theoretical sequence of the bond breaking reaction pathways have been found. This consistency between the theoretical predictions and the experimental observations provides strong supportive evidences for the base-centered radical anion mechanism of the LEE-induced single-strand bond breaking around the pyrimidine sites of the DNA single strands. PMID:20430827

Wafer-to-wafer bonding of nonplanarized MEMS surfaces using solder

NASA Astrophysics Data System (ADS)

Sparks, D.; Queen, G.; Weston, R.; Woodward, G.; Putty, M.; Jordan, L.; Zarabadi, S.; Jayakar, K.

2001-11-01

The fabrication and reliability of a solder wafer-to-wafer bonding process is discussed. Using a solder reflow process allows vacuum packaging to be accomplished with unplanarized complementary metal-oxide semiconductor (CMOS) surface topography. This capability enables standard CMOS processes, and integrated microelectromechanical systems devices to be packaged at the chip-level. Alloy variations give this process the ability to bond at lower temperatures than most alternatives. Factors affecting hermeticity, shorts, Q values, shifting cavity pressure, wafer saw cleanliness and corrosion resistance will be covered.

Comprehensive analysis of individual pulp fiber bonds quantifies the mechanisms of fiber bonding in paper

PubMed Central

Hirn, Ulrich; Schennach, Robert

2015-01-01

The process of papermaking requires substantial amounts of energy and wood consumption, which contributes to larger environmental costs. In order to optimize the production of papermaking to suit its many applications in material science and engineering, a quantitative understanding of bonding forces between the individual pulp fibers is of importance. Here we show the first approach to quantify the bonding energies contributed by the individual bonding mechanisms. We calculated the impact of the following mechanisms necessary for paper formation: mechanical interlocking, interdiffusion, capillary bridges, hydrogen bonding, Van der Waals forces, and Coulomb forces on the bonding energy. Experimental results quantify the area in molecular contact necessary for bonding. Atomic force microscopy experiments derive the impact of mechanical interlocking. Capillary bridges also contribute to the bond. A model based on the crystal structure of cellulose leads to values for the chemical bonds. In contrast to general believe which favors hydrogen bonding Van der Waals bonds play the most important role according to our model. Comparison with experimentally derived bond energies support the presented model. This study characterizes bond formation between pulp fibers leading to insight that could be potentially used to optimize the papermaking process, while reducing energy and wood consumption. PMID:26000898

An Analysis of the New Jersey Public School District School Bond Referendum Process: A Historical Case Study of the Egg Harbor Township School District Bond Referendum of 2004-05

ERIC Educational Resources Information Center

Werner, Michael J.

2012-01-01

This dissertation presents a historical case study of the Egg Harbor Township School District bond referendum that passed with an exceptionally high 92 percent of votes in January 2005. The methodology used in this study resulted in both an examination of the components of the New Jersey Public School District bond referendum process as well as an…

Manufacture of thin-walled clad tubes by pressure welding of roll bonded sheets

NASA Astrophysics Data System (ADS)

Schmidt, Hans Christian; Grydin, Olexandr; Stolbchenko, Mykhailo; Homberg, Werner; Schaper, Mirko

2017-10-01

Clad tubes are commonly manufactured by fusion welding of roll bonded metal sheets or, mechanically, by hydroforming. In this work, a new approach towards the manufacture of thin-walled tubes with an outer diameter to wall thickness ratio of about 12 is investigated, involving the pressure welding of hot roll bonded aluminium-steel strips. By preparing non-welded edges during the roll bonding process, the strips can be zip-folded and (cold) pressure welded together. This process routine could be used to manufacture clad tubes in a continuous process. In order to investigate the process, sample tube sections with a wall thickness of 2.1 mm were manufactured by U-and O-bending from hot roll bonded aluminium-stainless steel strips. The forming and welding were carried out in a temperature range between RT and 400°C. It was found that, with the given geometry, a pressure weld is established at temperatures starting above 100°C. The tensile tests yield a maximum bond strength at 340°C. Micrograph images show a consistent weld of the aluminium layer over the whole tube section.

Tick Talk: Block Tick Bites and Lyme Disease

MedlinePlus

... Subscribe May 2014 Print this issue Tick Talk Block Tick Bites and Lyme Disease En español Send ... Health Researchers Examine the Structure of Zika Virus Block the Buzzing, Bites, and Bumps Wise Choices To ...

Latex Allergy

MedlinePlus

... the material touches the skin. This is called contact dermatitis. Red, itchy bumps or blisters usually appear within ... powdered gloves are used and avoid all direct contact with latex. ... to get a skin rash reaction to latex, latex gloves made without additional ...

Eyelid bump

MedlinePlus

... 423. Review Date 8/20/2016 Updated by: Franklin W. Lusby, MD, ophthalmologist, Lusby Vision Institute, La Jolla, CA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team. Eyelid Disorders Read more ...

Low-temperature wafer-level gold thermocompression bonding: modeling of flatness deviations and associated process optimization for high yield and tough bonds

NASA Astrophysics Data System (ADS)

Stamoulis, Konstantinos; Tsau, Christine H.; Spearing, S. Mark

2005-01-01

Wafer-level, thermocompression bonding is a promising technique for MEMS packaging. The quality of the bond is critically dependent on the interaction between flatness deviations, the gold film properties and the process parameters and tooling used to achieve the bonds. The effect of flatness deviations on the resulting bond is investigated in the current work. The strain energy release rate associated with the elastic deformation required to overcome wafer bow is calculated. A contact yield criterion is used to examine the pressure and temperature conditions required to flatten surface roughness asperities in order to achieve bonding over the full apparent area. The results are compared to experimental data of bond yield and toughness obtained from four-point bend delamination testing and microscopic observations of the fractured surfaces. Conclusions from the modeling and experiments indicate that wafer bow has negligible effect on determining the variability of bond quality and that the well-bonded area is increased with increasing bonding pressure. The enhanced understanding of the underlying deformation mechanisms allows for a better controlled trade-off between the bonding pressure and temperature.

Low-temperature wafer-level gold thermocompression bonding: modeling of flatness deviations and associated process optimization for high yield and tough bonds

NASA Astrophysics Data System (ADS)

Stamoulis, Konstantinos; Tsau, Christine H.; Spearing, S. Mark

2004-12-01

Wafer-level, thermocompression bonding is a promising technique for MEMS packaging. The quality of the bond is critically dependent on the interaction between flatness deviations, the gold film properties and the process parameters and tooling used to achieve the bonds. The effect of flatness deviations on the resulting bond is investigated in the current work. The strain energy release rate associated with the elastic deformation required to overcome wafer bow is calculated. A contact yield criterion is used to examine the pressure and temperature conditions required to flatten surface roughness asperities in order to achieve bonding over the full apparent area. The results are compared to experimental data of bond yield and toughness obtained from four-point bend delamination testing and microscopic observations of the fractured surfaces. Conclusions from the modeling and experiments indicate that wafer bow has negligible effect on determining the variability of bond quality and that the well-bonded area is increased with increasing bonding pressure. The enhanced understanding of the underlying deformation mechanisms allows for a better controlled trade-off between the bonding pressure and temperature.

The influence of dynamical friction and mean motion resonances on terrestrial planet growth

NASA Astrophysics Data System (ADS)

Wallace, Spencer Clark; Quinn, Thomas R.

2018-04-01

We present a set of high-resolution direct N-body simulations of planetesimal coagulation at 1 AU. We follow the evolution of of 1 million planetesimals in a ring though the runaway and oligarchic growth phases. During oligarchic growth, the size frequency distribution (SFD) of planetesimals develops a bump at intermediate masses, which we argue is due to dynamical friction acting through mean motion resonances, heating the low mass planetesimals and inhibiting their growth. This feature is similar to the bump seen in the SFD of asteroid belt and Kuiper belt objects and we argue that a careful treatment of the dynamics of planetesimal interactions is required in order to adequately explain the observed SFD. Although our model does not account for fragmentation, our results show that a similar feature can be produced without it, which is in contention with previous studies.

Comparative pulsation calculations with OP and OPAL opacities

NASA Technical Reports Server (NTRS)

Kanbur, Shashi M.; Simon, Norman R.

1994-01-01

Comparative linear nonadiabatic pulsation calculations are presented using the OPAL and Opacity Project opacities. The two sets of opacities include effects due to intermediate coupling and fine structure as well as new abundances. We used two mass luminosity (M-L) relations, one standard (BIT), and one employing substantial convective core overshoot (COV). The two sets of opacities cannot be differentiated on the basis of the stellar pulsation calculations presented here. The BIT relation can model the beat and bump Cepheids with masses between 4 and 7 solar mass, while if the overshoot relation is used, masses between 2 and 6 solar mass are required. In the RR Lyrae regime, we find the inferred masses of globular cluster RRd stars to be little influenced by the choice of OPAL or OP. Finally, the limited modeling we have done is not able to constrain the Cepheid M-L relation based upon period ratios observed in the beat and bump stars.

Feeling socially powerless makes you more prone to bumping into things on the right and induces leftward line bisection error.

PubMed

Wilkinson, David; Guinote, Ana; Weick, Mario; Molinari, Rosanna; Graham, Kylee

2010-12-01

Social power affects the manner in which people view themselves and act toward others, a finding that has attracted broad interest from the social and political sciences. However, there has been little interest from those within cognitive neuroscience. Here, we demonstrate that the effects of power extend beyond social interaction and invoke elementary spatial biases in behavior consistent with preferential hemispheric activation. In particular, participants who felt relatively powerless, compared with those who felt more powerful, were more likely to bisect horizontal lines to the left of center, and bump into the right-hand (as opposed to the left-hand) side when walking through a narrow passage. These results suggest that power induces hemispheric differences in visuomotor behavior, indicating that this ubiquitous phenomenon affects not only how we interact with one another, but also how we interact with the physical world.

Method to simulate and analyse induced stresses for laser crystal packaging technologies.

PubMed

Ribes-Pleguezuelo, Pol; Zhang, Site; Beckert, Erik; Eberhardt, Ramona; Wyrowski, Frank; Tünnermann, Andreas

2017-03-20

A method to simulate induced stresses for a laser crystal packaging technique and the consequent study of birefringent effects inside the laser cavities has been developed. The method has been implemented by thermo-mechanical simulations implemented with ANSYS 17.0. ANSYS results were later imported in VirtualLab Fusion software where input/output beams in terms of wavelengths and polarization were analysed. The study has been built in the context of a low-stress soldering technique implemented for glass or crystal optics packaging's called the solderjet bumping technique. The outcome of the analysis showed almost no difference between the input and output laser beams for the laser cavity constructed with an yttrium aluminum garnet active laser crystal, a second harmonic generator beta-barium borate, and the output laser mirror made of fused silica assembled by the low-stress solderjet bumping technique.

Sonography of pediatric superficial lumps and bumps: illustrative examples from head to toe.

PubMed

Bansal, Anmol Gupta; Rosenberg, Henrietta Kotlus

2017-08-01

Superficial lumps and bumps are extremely common in children, and the vast majority ultimately prove to be benign. Duplex/color Doppler ultrasound (US) has emerged as the first-line imaging modality for the evaluation of these superficial pediatric masses because it provides a means for rapid acquisition of information including size, shape, location, internal content and vascularity. More important, it does so without utilizing radiation, iodinated contrast material or sedation/anesthesia. In this review, we present the sonographic findings of a variety of cases ranging from head to toe that are either uncommonly seen or were diagnosed in an atypical fashion (i.e. ultrasound). In situations where the lesion is too deep, hyperechoic or large to be fully assessed within the field of view or if malignancy is suspected, then additional cross-sectional imaging is warranted for further evaluation.

A comparison of the aerodynamic characteristics at transonic speeds of four wing-fuselage configurations as determined from different test techniques, 4 October 1960

NASA Technical Reports Server (NTRS)

Donlan, C. J.; Myers, B. C., II; Mattson, A. T.

1976-01-01

The high speed aerodynamic characteristics of a family of four wing-fuselage configurations of 0, 35, 45, and 60 deg sweepback were determined from transonic bump model tests that were conducted in the Langley high speed 7 by 10 foot tunnel; sting supported model tests were conducted in the Langley 8 foot high speed tunnel and in the Langley high speed 7 by 10 foot tunnel, and rocket model tests were conducted by the Langley Pilotless Aircraft Research Division. A complementary study of the effect of Mach number gradients and streamline curvature on bump results is also included. The qualitative data obtained from the various test facilities for the wing-fuselage configurations were in essential agreement as regards the relative effects of sweepback and Mach number except for drag at zero lift. Quantitatively, important differences were present.

Saturation of the junction voltage in GaN-based laser diodes

NASA Astrophysics Data System (ADS)

Feng, M. X.; Liu, J. P.; Zhang, S. M.; Liu, Z. S.; Jiang, D. S.; Li, Z. C.; Wang, F.; Li, D. Y.; Zhang, L. Q.; Wang, H.; Yang, H.

2013-05-01

Saturation of the junction voltage in GaN-based laser diodes (LDs) is studied. It is found that there is a bump above the lasing transition in the I(dV/dI)-I curve, instead of a dip as that for GaAs-based LDs. The bump in I(dV/dI)-I curve moves to higher currents along with the lasing threshold. A model considering ambipolar conduction and electron overflow into p-AlGaN cladding layer due to poor carrier confinement in active region is used to explain the anomaly. The characteristic temperature of GaN-based LD is obtained by fitting threshold currents determined from I(dV/dI)-I curves. Moreover, it is found that GaN-based LDs show characteristics with a nonlinear series resistance, which may be due to the electron overflow into p-AlGaN cladding layer and the enhanced activation of Mg acceptors.

The effects on cruise drag of installing long-duct refan-engine nacelles on the McDonnell Douglas DC-8-50 and -61

NASA Technical Reports Server (NTRS)

Callaghan, J. T.; Donelson, J. E.; Morelli, J. P.

1973-01-01

A high-speed wind tunnel test was conducted to determine the effect on cruise performance of installing long-duct refan-engine nacelles on the DC-8-50 and -61 models. Drag data and wing/pylon/nacelle channel pressure data are presented. At a typical cruise condition there exists a very small interference drag penalty of less than one-percent of total cruise data for the Refan installation. Pressure data indicate that some supersonic flow is present in the inboard channel of the inboard refan nacelle installation, but it is not sufficient to cause any wave drag on boundary layer separation. One pylon modification, which takes the form of pylon bumps, was tested. It resulted in a drag penalty, because its design goal of eliminating shock-related interference drag was not required and the bump thus became a source of additional parasite drag.

Linear Look-Ahead in Conjunctive Cells: An Entorhinal Mechanism for Vector-Based Navigation

PubMed Central

Kubie, John L.; Fenton, André A.

2012-01-01

The crisp organization of the “firing bumps” of entorhinal grid cells and conjunctive cells leads to the notion that the entorhinal cortex may compute linear navigation routes. Specifically, we propose a process, termed “linear look-ahead,” by which a stationary animal could compute a series of locations in the direction it is facing. We speculate that this computation could be achieved through learned patterns of connection strengths among entorhinal neurons. This paper has three sections. First, we describe the minimal grid cell properties that will be built into our network. Specifically, the network relies on “rigid modules” of neurons, where all members have identical grid scale and orientation, but differ in spatial phase. Additionally, these neurons must be densely interconnected with synapses that are modifiable early in the animal’s life. Second, we investigate whether plasticity during short bouts of locomotion could induce patterns of connections amongst grid cells or conjunctive cells. Finally, we run a simulation to test whether the learned connection patterns can exhibit linear look-ahead. Our results are straightforward. A simulated 30-min walk produces weak strengthening of synapses between grid cells that do not support linear look-ahead. Similar training in a conjunctive cell module produces a small subset of very strong connections between cells. These strong pairs have three properties: the pre- and post-synaptic cells have similar heading direction. The cell pairs have neighboring grid bumps. Finally, the spatial offset of firing bumps of the cell pair is in the direction of the common heading preference. Such a module can produce strong and accurate linear look-ahead starting in any location and extending in any direction. We speculate that this process may: (1) compute linear paths to goals; (2) update grid cell firing during navigation; and (3) stabilize the rigid modules of grid cells and conjunctive cells. PMID:22557948

Integrated Electrode Arrays for Neuro-Prosthetic Implants

NASA Technical Reports Server (NTRS)

Brandon, Erik; Mojarradi, Mohammede

2003-01-01

Arrays of electrodes integrated with chip-scale packages and silicon-based integrated circuits have been proposed for use as medical electronic implants, including neuro-prosthetic devices that might be implanted in brains of patients who suffer from strokes, spinal-cord injuries, or amyotrophic lateral sclerosis. The electrodes of such a device would pick up signals from neurons in the cerebral cortex, and the integrated circuit would perform acquisition and preprocessing of signal data. The output of the integrated circuit could be used to generate, for example, commands for a robotic arm. Electrode arrays capable of acquiring electrical signals from neurons already exist, but heretofore, there has been no convenient means to integrate these arrays with integrated-circuit chips. Such integration is needed in order to eliminate the need for the extensive cabling now used to pass neural signals to data-acquisition and -processing equipment outside the body. The proposed integration would enable progress toward neuro-prostheses that would be less restrictive of patients mobility. An array of electrodes would comprise a set of thin wires of suitable length and composition protruding from and supported by a fine-pitch micro-ball grid array or chip-scale package (see figure). The associated integrated circuit would be mounted on the package face opposite the probe face, using the solder bumps (the balls of the ball grid array) to make the electrical connections between the probes and the input terminals of the integrated circuit. The key innovation is the insertion of probe wires of the appropriate length and material into the solder bumps through a reflow process, thereby fixing the probes in place and electrically connecting them with the integrated circuit. The probes could be tailored to any distribution of lengths and made of any suitable metal that could be drawn into fine wires. Furthermore, the wires could be coated with an insulating layer using anodization or other processes, to achieve the correct electrical impedance. The probe wires and the packaging materials must be biocompatible using such materials as lead-free solders. For protection, the chip and package can be coated with parylene.

Verification of the modified model of the drying process of a polymer liquid film on a flat substrate by experiment (2): through more accurate experiment

NASA Astrophysics Data System (ADS)

Kagami, Hiroyuki

2006-05-01

We have proposed and modified a model of drying process of polymer solution coated on a flat substrate for flat polymer film fabrication and have presented the fruits through Photomask Japan 2002, 2003, 2004 and so on. And for example numerical simulation of the model qualitatively reappears a typical thickness profile of the polymer film formed after drying, that is, the profile that the edge of the film is thicker and just the region next to the edge's bump is thinner. Then we have clarified dependence of distribution of polymer molecules on a flat substrate on a various parameters based on analysis of many numerical simulations. Then we done a few kinds of experiments so as to verify the modified model and reported the initial result of them through Photomask Japan 2005. Through the initial result we could observe some results supporting the modified model. But we could not observe a characteristic region of a valley next to the edge's bump of a polymer film after drying because a shape of a solution's film coated on a substrate in the experiment was different from one in resists' coating and drying process or imagined in the modified model. In this study, we improved above difference between experiment and the model and did experiments for verification again with a shape of a solution's film coated on a substrate coincident with one imagined in the modified model and using molar concentration. As a result, some were verified more strongly and some need to be examined again. That is, we could confirm like results of last experiment that the smaller average molecular weight of Metoloses was, the larger the gradient of thickness profile of a polymer thin film was. But we could not observe a depression just inside the edge of the thin film also in this improved experiment. We may be able to enumerate the fact that not an organic solution but an aqueous solution was used in the experiment as the cause of non-formation of the depression.

The decision process used for hospital bond rating--and its implications.

PubMed Central

Cleverley, W O; Nutt, P C

1984-01-01

Investigation of the process of hospital bond rating related the ratings assigned by Moody's and Standard and Poors to indicators of hospital financial condition (such as debt per bed and peak debt coverage), institutional factors (including size, occupancy, and local market competition), indenture provisions (such as reserves), and contextual factors. The criteria used by Moody's and Standard and Poors to rate hospital bonds were revealed to be similar, but not identical. Criteria used in the bond rating process have several important implications: the rating approach provides strong financial incentives for increases in hospital size and complexity, for example, and hospitals that rely on extensive amounts of public financing appear to be penalized in the rating process. PMID:6500959

Advanced thermal barrier coatings for operation in high hydrogen content fueled gas turbines.

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

Sampath, Sanjay

2015-04-02

The Center for Thermal Spray Research (CTSR) at Stony Brook University in partnership with its industrial Consortium for Thermal Spray Technology is investigating science and technology related to advanced metallic alloy bond coats and ceramic thermal barrier coatings for applications in the hot section of gasified coal-based high hydrogen turbine power systems. In conjunction with our OEM partners (GE and Siemens) and through strategic partnership with Oak Ridge National Laboratory (ORNL) (materials degradation group and high temperature materials laboratory), a systems approach, considering all components of the TBC (multilayer ceramic top coat, metallic bond coat & superalloy substrate) is beingmore » taken during multi-layered coating design, process development and subsequent environmental testing. Recent advances in process science and advanced in situ thermal spray coating property measurement enabled within CTSR has been incorporated for full-field enhancement of coating and process reliability. The development of bond coat processing during this program explored various aspects of processing and microstructure and linked them to performance. The determination of the bond coat material was carried out during the initial stages of the program. Based on tests conducted both at Stony Brook University as well as those carried out at ORNL it was determined that the NiCoCrAlYHfSi (Amdry) bond coats had considerable benefits over NiCoCrAlY bond coats. Since the studies were also conducted at different cycling frequencies, thereby addressing an associated need for performance under different loading conditions, the Amdry bond coat was selected as the material of choice going forward in the program. With initial investigations focused on the fabrication of HVOF bond coats and the performance of TBC under furnace cycle tests , several processing strategies were developed. Two-layered HVOF bond coats were developed to render optimal balance of density and surface roughness and resulted in improved TBC lifetimes. Processing based approaches of identifying optimal processing regimes deploying advanced in-situ coating property measurements and in-flight diagnostic tools were used to develop process maps for bond coats. Having established a framework for the bond coat processing using the HVOF process, effort were channeled towards fabrication of APS and VPS bond coats with the same material composition. Comparative evaluation of the three deposition processes with regard to their microstrcuture , surface profiles and TBC performance were carried out and provided valuable insights into factors that require concurrent consideration for the development of bond coats for advanced TBC systems. Over the course of this program several advancements were made on the development of durable thermal barrier coatings. Process optimization techniques were utilized to identify processing regimes for both conventional YSZ as well as other TBC compositions such as Gadolinium Zirconate and other Co-doped materials. Measurement of critical properties for these formed the initial stages of the program to identify potential challenges in their implementation as part of a TBC system. High temperature thermal conductivity measurements as well as sintering behavior of both YSZ and GDZ coatings were evaluated as part of initial efforts to undersand the influence of processing on coating properties. By effectively linking fundamental coating properties of fracture toughness and elastic modulus to the cyclic performance of coatings, a durability strategy for APS YSZ coatings was developed. In order to meet the goals of fabricating a multimaterial TBC system further research was carried out on the development of a gradient thermal conductivity model and the evaluation of sintering behavior of multimaterial coatings. Layer optimization for desired properties in the multimaterial TBC was achieved by an iterative feedback approach utilizing process maps and in-situ and ex-situ coating property sensors. Addressing the challenges pertaining to the integration of the two materials YSZ and GDZ led to one of most the critical outcomes of this program, the development of durable multimaterial, multifunctional TBC systems.« less

Liquid phase diffusion bonding of A1070 by using metal formate coated Zn sheet

NASA Astrophysics Data System (ADS)

Ozawa, K.; Koyama, S.; shohji, I.

2017-05-01

Aluminium alloy have high strength and easily recycle due to its low melting point. Therefore, aluminium is widely used in the manufacturing of cars and electronic devices. In recent years, the most common way for bonding aluminium alloy is brazing and friction stir welding. However, brazing requires positional accuracy and results in the formation of voids by the flax residue. Moreover, aluminium is an excellent heat radiating and electricity conducting material; therefore, it is difficult to bond together using other bonding methods. Because of these limitations, liquid phase diffusion bonding is considered to the suitable method for bonding aluminium at low temperature and low bonding pressure. In this study, the effect of metal formate coating processing of zinc surface on the bond strength of the liquid phase diffusion bonded interface of A1070 has been investigated by SEM observation of the interfacial microstructures and fractured surfaces after tensile test. Liquid phase diffusion bonding was carried out under a nitrogen gas atmosphere at a bonding temperature of 673 K and 713 K and a bonding load of 6 MPa (bonding time: 15 min). As a result of the metal formate coating processing, a joint having the ultimate tensile strength of the base aluminium was provided. It is hypothesized that this is because metallic zinc is generated as a result of thermal decomposition of formate in the bonded interface at lower bonding temperatures.

Feasibility study of solid surface subreflector production techniques

NASA Technical Reports Server (NTRS)

1982-01-01

The principal effort was to study technical feasibility and cost aspects of the production technique of spin forming a subreflector reflective surface to a desired surface of revolution, back the surface with fiberglass to stabilize it sufficiently so that it may be machined to the target surface tolerance of .008 inches Root Mean Square (RMS) with a goal of .003 inches RMS. To verify this production technique, analyses was performed to define the production procedure. A price estimate for a 150 inch diameter subreflector for a 34 meter cassegrain antenna. During this feasibility study, numerous production processes were evaluated theoretically as production approaches for single surface, non-welded subreflectors. The first successful was the principal process of spin forming the reflective surface, backing with fiberglass and machining to a final contour. The second successful process was spin forming or bump forming a thicker reflective surface, with an integral (welded in) structure as a backing and machining the mounting pads and reflector to a final configuration.

46 CFR 154.514 - Piping: Electrical bonding.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 5 2011-10-01 2011-10-01 false Piping: Electrical bonding. 154.514 Section 154.514... and Process Piping Systems § 154.514 Piping: Electrical bonding. (a) Cargo tanks or piping that are... side. (c) An electrical bond must be made by at least one of the following methods: (1) A metal bonding...

46 CFR 154.514 - Piping: Electrical bonding.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 5 2012-10-01 2012-10-01 false Piping: Electrical bonding. 154.514 Section 154.514... and Process Piping Systems § 154.514 Piping: Electrical bonding. (a) Cargo tanks or piping that are... side. (c) An electrical bond must be made by at least one of the following methods: (1) A metal bonding...

46 CFR 154.514 - Piping: Electrical bonding.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 5 2013-10-01 2013-10-01 false Piping: Electrical bonding. 154.514 Section 154.514... and Process Piping Systems § 154.514 Piping: Electrical bonding. (a) Cargo tanks or piping that are... side. (c) An electrical bond must be made by at least one of the following methods: (1) A metal bonding...

27 CFR 40.133 - Amount of individual bond.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 27 Alcohol, Tobacco Products and Firearms 2 2012-04-01 2011-04-01 true Amount of individual bond. 40.133 Section 40.133 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU..., AND PROCESSED TOBACCO Bonds and Extensions of Coverage of Bonds § 40.133 Amount of individual bond...

The effect of silica-coating by sol-gel process on resin-zirconia bonding.

PubMed

Lung, Christie Ying Kei; Kukk, Edwin; Matinlinna, Jukka Pekka

2013-01-01

The effect of silica-coating by sol-gel process on the bond strength of resin composite to zirconia was evaluated and compared against the sandblasting method. Four groups of zirconia samples were silica-coated by sol-gel process under varied reagent ratios of ethanol, water, ammonia and tetraethyl orthosilicate and for different deposition times. One control group of zirconia samples were treated with sandblasting. Within each of these five groups, one subgroup of samples was kept in dry storage while another subgroup was aged by thermocycling for 6,000 times. Besides shear bond testing, the surface topography and surface elemental composition of silica-coated zirconia samples were also examined using scanning electron microscopy and X-ray photoelectron spectroscopy. Comparison of silica coating methods revealed significant differences in bond strength among the Dry groups (p<0.001) and Thermocycled groups (p<0.001). Comparison of sol-gel deposition times also revealed significant differences in bond strength among the Dry groups (p<0.01) and Thermocycled groups (p<0.001). Highest bond strengths were obtained after 141-h deposition: Dry (7.97±3.72 MPa); Thermocycled (2.33±0.79 MPa). It was concluded that silica-coating of zirconia by sol-gel process resulted in weaker resin bonding than by sandblasting.

Transition metal-catalyzed process for addition of amines to carbon-carbon double bonds

DOEpatents

Hartwig, John F.; Kawatsura, Motoi; Loeber, Oliver

2002-01-01

The present invention is directed to a process for addition of amines to carbon-carbon double bonds in a substrate, comprising: reacting an amine with a compound containing at least one carbon-carbon double bond in the presence a transition metal catalyst under reaction conditions effective to form a product having a covalent bond between the amine and a carbon atom of the former carbon-carbon double bond. The transition metal catalyst comprises a Group 8 metal and a ligand containing one or more 2-electron donor atoms. The present invention is also directed to enantioselective reactions of amine compounds with compounds containing carbon-carbon double bonds, and a calorimetric assay to evaluate potential catalysts in these reactions.

Random Photon Absorption Model Elucidates How Early Gain Control in Fly Photoreceptors Arises from Quantal Sampling

PubMed Central

Song, Zhuoyi; Zhou, Yu; Juusola, Mikko

2016-01-01

Many diurnal photoreceptors encode vast real-world light changes effectively, but how this performance originates from photon sampling is unclear. A 4-module biophysically-realistic fly photoreceptor model, in which information capture is limited by the number of its sampling units (microvilli) and their photon-hit recovery time (refractoriness), can accurately simulate real recordings and their information content. However, sublinear summation in quantum bump production (quantum-gain-nonlinearity) may also cause adaptation by reducing the bump/photon gain when multiple photons hit the same microvillus simultaneously. Here, we use a Random Photon Absorption Model (RandPAM), which is the 1st module of the 4-module fly photoreceptor model, to quantify the contribution of quantum-gain-nonlinearity in light adaptation. We show how quantum-gain-nonlinearity already results from photon sampling alone. In the extreme case, when two or more simultaneous photon-hits reduce to a single sublinear value, quantum-gain-nonlinearity is preset before the phototransduction reactions adapt the quantum bump waveform. However, the contribution of quantum-gain-nonlinearity in light adaptation depends upon the likelihood of multi-photon-hits, which is strictly determined by the number of microvilli and light intensity. Specifically, its contribution to light-adaptation is marginal (≤ 1%) in fly photoreceptors with many thousands of microvilli, because the probability of simultaneous multi-photon-hits on any one microvillus is low even during daylight conditions. However, in cells with fewer sampling units, the impact of quantum-gain-nonlinearity increases with brightening light. PMID:27445779

Cross-validation and Peeling Strategies for Survival Bump Hunting using Recursive Peeling Methods

PubMed Central

Dazard, Jean-Eudes; Choe, Michael; LeBlanc, Michael; Rao, J. Sunil

2015-01-01

We introduce a framework to build a survival/risk bump hunting model with a censored time-to-event response. Our Survival Bump Hunting (SBH) method is based on a recursive peeling procedure that uses a specific survival peeling criterion derived from non/semi-parametric statistics such as the hazards-ratio, the log-rank test or the Nelson--Aalen estimator. To optimize the tuning parameter of the model and validate it, we introduce an objective function based on survival or prediction-error statistics, such as the log-rank test and the concordance error rate. We also describe two alternative cross-validation techniques adapted to the joint task of decision-rule making by recursive peeling and survival estimation. Numerical analyses show the importance of replicated cross-validation and the differences between criteria and techniques in both low and high-dimensional settings. Although several non-parametric survival models exist, none addresses the problem of directly identifying local extrema. We show how SBH efficiently estimates extreme survival/risk subgroups unlike other models. This provides an insight into the behavior of commonly used models and suggests alternatives to be adopted in practice. Finally, our SBH framework was applied to a clinical dataset. In it, we identified subsets of patients characterized by clinical and demographic covariates with a distinct extreme survival outcome, for which tailored medical interventions could be made. An R package PRIMsrc (Patient Rule Induction Method in Survival, Regression and Classification settings) is available on CRAN (Comprehensive R Archive Network) and GitHub. PMID:27034730