Electromagnetic Scattering From Multilayer Rough Surfaces With Arbitrary Dielectric Profiles for Remote Sensing of Subsurface Soil Moisture

Radar remote sensing of soil moisture content at low frequencies requires an accurate scattering model of realistic soils, which often involves multilayer rough surfaces and dielectric profiles. In this paper, a hybrid analytical/numerical solution to two-dimensional scattering from multilayer rough surfaces separated by arbitrary dielectric profiles based on the extended boundary condition method (EBCM) and scattering matrix technique is presented. The reflection and transmission matrices of rough interfaces are constructed using EBCM. The dielectric profiles are modeled as stacks of piecewise homogeneous dielectric thin layers, whose scattering matrices are computed by recursively cascading reflection and transmission matrices of individual dielectric interfaces. The interactions between the rough interfaces and stratified dielectric profiles are taken into account by applying the generalized scattering matrix technique. The scattering coefficients are obtained by combining the powers computed from the resulting Floquet modes of the overall system. The bistatic scattering coefficients are validated against existing analytical and numerical solutions. Field-collected soil moisture data are then used for numerical simulations to investigate the penetration capability at different frequencies and to address the potential of low-frequency radar systems in estimating deep soil moisture. In particular, soil moisture profiles during dry ground, wet ground, and wet subsurface layer conditions are examined. The results show that both backscattering coefficients and copolarized phase difference at low frequencies are sensitive to the roughness of subsurface interfaces and deep soil moisture. Also, much larger depth sensitivity can be achieved using copolarized phase difference than scattering coefficients     

High Brightness GaN-Based Light-Emitting Diodes

This paper reviews our recent progress of GaN-based high brightness light-emitting diodes (LEDs). Firstly, by adopting chemical wet etching patterned sapphire substrates in GaN-based LEDs, not only could increase the extraction quantum efficiency, but also improve the internal quantum efficiency. Secondly, we present a high light-extraction 465-nm GaN-based vertical light-emitting diode structure with double diffuse surfaces. The external quantum efficiency was demonstrated to be about 40%. The high performance LED was achieved mainly due to the strong guided-light scattering efficiency while employing double diffuse surfaces     

Run-by-Run Process Control of Metal Sputter Deposition: Combining Time Series and Extended Kalman Filter

By the time series model, this paper constructed the disturbance model for the aluminum sputter deposition process and derived the extending Kalman filter (EKF) controller based on this new disturbance model. Experimental results reveal that ARI(3,1) model appropriately characterizes the dynamic behavior of the disturbance for the processes. The EKF controller which includes information of process noise and measurement noise is able to regulate the model coefficients automatically as the target is replaced or degrades. In this paper, the d-EWMA controller, time-varying d-EWMA controller, age-based d-EWMA controller, and EKF controller have been applied to aluminum sputter deposition processes for predicting deposition rates and comparing their performances. The application of the EKF controller here is proven to improve the estimating accuracy of the aluminum sputter deposition process significantly, regardless of whether the deposition rates are measured at each run or not.     

Single nucleotide polymorphism data analysis - State-of-the-art review on this emerging field from a signal processing viewpoint

The basic structural units of the genome are nucleotides. A single nucleotide polymorphism (SNP) is a mutation at a single nucleotide position. This paper discusses several major problems in SNP data analysis and review some existing solutions in this work. Generally speaking, a rich set of SNP analysis problems are cast in the signal processing framework. Our objective is to offer a state-of-the art review on this topic from a signal processing viewpoint so that researchers in the signal processing field can grasp the important domain knowledge to overcome the barrier between the two fields     

Characterization and Properties of Nickel Aluminide Nanocrystals in an Alumina Layer for Nonvolatile Memory Applications

Intermetallic nanocrystal memory devices with nickel aluminide nanocrystals in the electron-trapping layer and an alumina layer as the blocking layer were prepared on the surface of oxidized silicon substrates by sputter-coating of Ni and Al₂O₃ in sequence, followed by an annealing procedure. Several aluminide nanocrystal memory devices are reported. The effect of annealing at 900°C on the memory properties was investigated. Intermetallic nanocrystals were identified by high-resolution transmission electron microscopy and x-ray photoelectron spectroscopy as Ni₂Al₃ with sizes of 15–20 nm. The results showed that a sixfold increase (0.37 V to 2.34 V) in the memory window could be achieved after annealing for the optimal time of 3 min.     

28 nm低功耗工艺SRAM失效分析

在28 nm低功耗工艺平台开发过程中,对1.26 V测试条件下出现的SRAM双比特失效问题进行了电性能失效模式分析及物性平面和物性断面分析.指出失效比特右侧位线接触孔底部空洞为SRAM制程上的缺陷所导致.并通过元素成分分析确定接触孔底部钨(W)的缺失,接触孔底部外围粘结阻挡层的氮化钛(TiN)填充完整.结合SRAM写操作的原理从电阻分压的机理上解释了较高压下双比特失效,1.05 V常压下单比特不稳定失效,0.84 V低电压下失效比特却通过测试的原因.1.26 V电压下容易发生的双比特失效是一种很特殊的SRAM失效,其分析过程及结论在集成电路制造行业尤其是对先进工艺制程研发过程具有较好的参考价值.     

H.264/SVC mode decision based on optimal stopping theory

Fast mode decision algorithms have been widely used in the video encoder implementation to reduce encoding complexity yet without much sacrifice in the coding performance. Optimal stopping theory, which addresses early termination for a generic class of decision problems, is adopted in this paper to achieve fast mode decision for the H.264/Scalable Video Coding standard. A constrained model is developed with optimal stopping, and the solutions to this model are employed to initialize the candidate mode list and predict the early termination. Comprehensive simulation results are conducted to demonstrate that the proposed method strikes a good balance between low encoding complexity and high coding efficiency.     

Reader Coverage Analysis for Multi-Carrier Passive UHF RFID Systems

Applications of passive radio frequency identification (RFID) systems have gained considerable attentions in recent years. Because a passive tag must obtain its operating power from a continuous wave transmitted from a reader in a conventional RFID system, reader coverage is limited. Thus, expanding reader coverage is a current goal in RFID research. In this work, passive tags are provided with additional operating power via continuous waves in multiple frequency bands. In an interrogation region, continuous wave emitters, which provide additional operating power to passive tags, are deployed according to the base station configuration in a cellular phone system. Because transmission power of continuous wave emitters must consider the reader command demodulation constraint and minimum operating power required by a tag, transmission power of continuous wave emitters must be chosen carefully. A method for analyzing reader coverage in multi-carrier passive UHF RFID systems is derived in this work. Assuming all tags are uniformly distributed in an interrogation region, the optimal continuous wave emitter transmission power that achieves the largest reader coverage can be analytically determined. Simulation results verify that continuous wave emitters with suitable transmission power expand reader coverage in a multi-carrier passive UHF RFID system. Additionally, adjusting reader power in the forward (reader-to-tag) link duration can loosen the reader command demodulation constraint and thereby further expand reader coverage.     

Multicast Parametric Synchronous Sampling of 320-Gb/s Return-to-Zero Signal

Technology for simultaneous demultiplexing of subrate tributaries is described and applied to 320-Gb/s return-to-zero input. The parametric architecture is scalable with respect to processed input rate and relies on cascaded all-optical multicasting and subrate sampling. Processing of 320-Gb/s input was achieved by creating eight channel copies, followed by a 20-THz-wide parametric gate. Multicasting was based on a self-seeded two-pump broadband fiber-optic parametric amplifier. The architecture was used to demonstrate error-free parallel demultiplexing of eight 320-Gb/s tributary channels at 40 Gb/s.     

Enhanced microstrip filter design with a uniform dielectric overlay for suppressing the second harmonic response

Parallel-coupled microstrip filters are designed to suppress spurious response at twice the passband frequency (2f/sub o/) with a uniform dielectric overlay. The overlay dielectric is used to equalize the modal phase velocities of each coupled stage. Based on the method, we have a large degree of freedom in choosing thickness and permittivity of the overlay dielectric. The image impedances of all the coupled stages in such a filter need adjusting to complete the filter synthesis. Two filters are fabricated and measured results show a good agreement with the simulation. A suppression of at least 40 dB to the spurious responses at 2f/sub o/ is achieved.