Foveation-Based Error Resilience and Unequal Error Protection over Mobile Networks

By exploiting new human-machine interface techniques, such as visual eyetrackers, it should be possible to develop more efficient visual multimedia services associated with low bandwidth, dynamic channel adaptation and robust visual data transmission. In this paper, we introduce foveation-based error resilience and unequal error protection techniques over highly error-prone mobile networks. Each frame is spatially divided into foveated and background layers according to perceptual importance. Perceptual importance is determined either through an eye tracker or by manually selecting a region of interest. We attempt to improve reconstructed visual quality by maintaining the high visual source throughput of the foveated layer using foveation-based error resilience and error correction using a combination of turbo codes and ARQ (automatic reQuest). In order to alleviate the degradation of visual quality, a foveation based bitstream partitioning is developed. In an effort to increase the source throughput of the foveated layer, we develop unequal delay-constrained ARQ (automatic reQuest) and rate compatible punctured turbo codes where the punctual pattern of RCPC (rate compatible punctured convolutional) codes in H.223 Annex C is used. In the simulation, the visual quality is significantly increased in the area of interest using foveation-based error resilience and unequal error protection; (as much as 3 dB FPSNR (foveal peak signal to noise ratio) improvement) at 40% packet error rate. Over real-fading statistics measured in the downtown area of Austin, Texas, the visual quality is increased up to 1.5 dB in PSNR and 1.8 dB in FPSNR at a channel SNR of 5 dB.     

Sensitivity analysis of simulations for magnetic particle inspection using the finite-element method

Magnetic particle inspection (MPI) is widely used for nondestructive evaluation in aerospace applications in which interpretation of inspection results is currently limited to empirical knowledge and experience-based approaches. Advances in computational magnetics, particularly the use of finite-element calculations, have enabled realistic numerical simulations of magnetic particle inspection to be undertaken with complicated geometries. In this paper, we report a sensitivity analysis using finite-element-method simulations of magnetic particle inspection for defects with various sizes and geometries. As a result, improved quantitative understanding of the MPI technique and factors that affects its sensitivity and reliability has been achieved. These results can be used to optimize conditions for conducting these inspections and should lead to improvement in analysis and interpretation of experimental results.     

Sensor technologies for monitoring metabolic activity in single cells-part I: optical methods

A review of optical, chemical, and biological sensors to detect metabolic activity at the single-cell level is presented in the context of the development of lab-on-a-chip research instrumentation. The sensors reviewed include optical sensors, at both research and commercial levels, that can optically detect intracellular metabolites including adenosine triphosphate, nicotinamide-adenine dinucleotide, reduced flavin adenine dinucleotide, and other metabolites, including oxygen, carbon dioxide, and glucose. Methods to optically detect pH changes which are a general indicator of activity in extracellular space are also briefly reviewed. Performance metrics such as sensitivity, sensor size, drift, time response, and sensing range are included when available. Highly suitable optical sensor technologies for monitoring cellular metabolic activity include luminescent (fluorescent, phosphorescent, and chemiluminescent) and colorimetric optical probes. Different approaches to extracting luminescent and colorimetric information are reviewed, including benchtop techniques, fiber-optic approaches, and the use of probes encapsulated by biologically localized embedding. A brief discussion of alternate optical sensor technologies, such as surface plasmon resonance and infrared absorption spectroscopy, is also presented.     

多粒度全光网中的多层联合路由

多粒度交换技术利用波带级路由以及光纤级路由,可有效降低光交叉连接器的复杂度.但多粒度交换增加了光网络的逻辑层次结构,使得网络中的路由与资源分配问题更为复杂,因此,在多粒度全光网中实现多层联合路由是提高网络性能的关键.本文对多粒度交叉连接结构进行了分析,并对多粒度全光网中的多层联合路由问题进行了研究.     

Bias-temperature instabilities of polysilicon gate HfO/sub 2/ MOSFETs

Bias-temperature instabilities (BTI) of HfO/sub 2/ metal oxide semiconductor field effect transistors (MOSFETs) have been systematically studied for the first time. NMOS positive BTI (PBTI) exhibited a more significant V/sub t/ instability than that of PMOS negative BTI (NBTI), and limited the lifetime of HfO/sub 2/ MOSFETs. Although high-temperature forming gas annealing (HT-FGA) improved the interface quality by passivating the interfacial states with hydrogen, BTI behaviors were not strongly affected by the technique. Charge pumping measurements were extensively used to investigate the nature of the BTI degradation, and it was found that V/sub t/ degradation of NMOS PBTI was primarily caused by charge trapping in bulk HfO/sub 2/ rather than interfacial degradation. Deuterium (D/sub 2/) annealing was found to be an excellent technique to improve BTI immunity as well as to enhance the mobility of HfO/sub 2/ MOSFETs.     

X-ray-based measurement of composition during electron beam melting of AISI 316 stainless steel: Part II. Evaporative processes and simulation

An energy dispersive X-ray (EDX) detector mounted on a laboratory scale electron beam furnace (30 kW) was employed to assess the potential use of X-rays as a means of on-line composition monitoring during electron beam (E B) melting of alloys. The design and construction of the collimation and protection systems used for the EDX are described in Part I. In Part II, a mathematical simulation of the heat, mass, and momentum transfer was performed for comparison to the EDX and vapor deposition results. The predicted flow patterns and evaporation rates are used to explain the differences between the two experimental methods. For the EDX spectra measured, the X-rays generated were from the center of the hearth where fluid flow rising from the bulk of the pool is sufficient to maintain the bulk composition despite the high evaporative flux from the surface. The flow moves radially outward from the center of the pool, with the volatile species being depleted. The vapor deposition technique measures the entire region, giving an average surface composition, and it therefore differs from the EDX results, which gave a near bulk composition. This combined study using in-situ EDX measurements and numerical simulations both provided an insight into the phenomena controlling the evaporation in an EB-heated system and demonstrated the viability of using EDX to measure the bulk composition during EB melting processes.     

An efficient implementation of SELF, a dynamically-typed object-oriented language based on prototypes

We have developed and implemented techniques that double the performance of dynamically-typed object-oriented languages. Our SELF implementation runs twice as fast as the fastest Smalltalk implementation, despite SELF's lack of classes and explicit variables.To compensate for the absence of classes, our system uses implementation-levelmaps to transparently group objects cloned from the same prototype, providing data type information and eliminating the apparent space overhead for prototype-based systems. To compensate for dynamic typing, user-defined control structures, and the lack of explicit variables, our system dynamically compilesmultiple versions of a source method, eachcustomized according to its receiver's map. Within each version the type of the receiver is fixed, and thus the compiler can statically bind andinline all messages sent toself.Message splitting andtype prediction extract and preserve even more static type information, allowing the compiler to inline many other messages. Inlining dramatically improves performance and eliminates the need to hard-wire low-level methods such as+, ==, andifTrue:.Despite inlining and other optimizations, our system still supports interactive programming environments. The system traverses internal dependency lists to invalidate all compiled methods affected by a programming change. The debugger reconstructs inlined stack frames from compiler-generated debugging information, making inlining invisible to the SELF programmer.This work has been generously supported by National Science Foundation Presidential Young Investigator Grant #CCR-8657631, and by IBM, Texas Instruments, NCR, Tandem Computers, Apple Computer, and Sun Microsystems.This paper was originally published inOOPSLA '89 Conference Proceedings (SIGPLAN Notices, 25, 10 (1989) 49–70).     

Investigations of high-performance GaAs solar cells grown on Ge-Si/sub 1-x/Ge/sub x/-Si substrates

High-performance p/sup +//n GaAs solar cells were grown and processed on compositionally graded Ge-Si/sub 1-x/Ge/sub x/-Si (SiGe) substrates. Total area efficiencies of 18.1% under the AM1.5-G spectrum were measured for 0.0444 cm/sup 2/ solar cells. This high efficiency is attributed to the very high open-circuit voltages (980 mV (AM0) and 973 mV (AM1.5-G)) that were achieved by the reduction in threading dislocation density enabled by the SiGe buffers, and thus reduced carrier recombination losses. This is the highest independently confirmed efficiency and open-circuit voltage for a GaAs solar cell grown on a Si-based substrate to date. Larger area solar cells were also studied in order to examine the impact of device area on GaAs-on-SiGe solar cell performance; we found that an increase in device area from 0.36 to 4.0 cm/sup 2/ did not degrade the measured performance characteristics for cells processed on identical substrates. Moreover, the device performance uniformity for large area heteroepitaxial cells is consistent with that of homoepitaxial cells; thus, device growth and processing on SiGe substrates did not introduce added performance variations. These results demonstrate that using SiGe interlayers to produce "virtual" Ge substrates may provide a robust method for scaleable integration of high performance III-V photovoltaics devices with large area Si wafers.