Electropolishing of 316L stainless steel for anticorrosion passivation

316L stainless steel is deemed an indispensable material in the semiconductor industry. In many instances, the surface of the production equipment needs to be treated for low-corrosion passivation, good finish, weldability, and cleanliness. The process characteristics of electropolishing meet these requirements well. The current study investigates the effects of the major processing parameters on the anticorrosion performance and the surface roughness. The electrolyte with 10% water content and a ratio between H₂SO₄ and H₃PO₄ of 4 and 6 has been proven to be successful, showing no corrosion pitting points on the specimen surface. The electrolyte temperature of 85±10 °C and the electrical current density of 0.5 to 1.0 A/cm² are found to be optimal. The processing time beyond 3 to 5 min produces no further improvement. The addition of 10% glycerin provides a very fine surface (maximum roughness of 0.05 μm), while the anticorrosion performance is deteriorated. The results obtained are useful for the manufacture of the semiconductor equipment.     

A cutting plane algorithm for robustness analysis of periodicallytime-varying systems

An algorithm for robustness analysis of periodic systems is derived. The system under consideration consists of a linear periodically time-varying plant in feedback interconnection with a structured uncertainty. Conditions for robust stability and robust performance can be formulated in terms of periodic integral quadratic constraints (IQCs). In this way, the robustness analysis becomes a problem of optimizing the parameters of the IQC. A cutting plane algorithm is suggested for solving this infinite-dimensional optimization problem     

Numerically exploring habitat fragmentation effects on populations using cell-based coupled map lattices

We examine habitat size, shape, and arrangement effects on populations using a discrete reaction-diffusion model. Diffusion is modeled passively and applied to a cellular grid of territories forming a coupled map lattice. Dispersal mortality is proportional to the amount of nonhabitat and fully occupied habitat surrounding a given cell, with distance decay. After verifying that our model produces the results expected for single patches of uniform habitat, we investigate heterogeneous and fragmented model landscapes. In heterogeneous single-patch systems near critical patch size, populations approach Gaussian spatial distributions with total population constrained by the capacity of the most limiting cell. In fragmented habitat landscapes, threshold effects are more complex and parametrically sensitive. The results from our experiments suggest the following: the ability to achieve persistence in hyperdispersed patchy habitats by adding similarly fragmented patches requires meeting threshold reproduction rates; persistent metapopulations in which no local population is individually persistent appear when dispersal distances and reproduction rates are both high, but only within narrow parameter ranges that are close to extinction thresholds; successful use of stepping-stone patches to support metapopulation systems appears unlikely for passively diffusing species; elongated patches offer early colonization advantages, but blocky patches offer greater population resilience near extinction thresholds. A common theme running through our findings is that population viability estimates may depend on our ability to determine when population and habitat systems are approaching extinction threshold conditions.     

A Fully Integrated 0.13 μm CMOS Low-IF DBS Satellite Tuner Using Automatic Signal-Path Gain and Bandwidth Calibration

This paper presents the first low-IF fully integrated receiver for DBS satellite TV applications realized in 0.13 mum CMOS. A wideband ring oscillator based frequency synthesizer having a large frequency step was used to downconvert a cluster of channels to a coarsely defined low-IF frequency, while the second downconversion to baseband was performed in the digital domain. Eliminating the oscillator inductors reduced the parasitic magnetic coupling from the digital core, allowing a single-chip integration of the sensitive tuner and the noisy digital demodulator. A significant die area reduction was achieved by using a single oscillator to cover the entire satellite TV spectrum, while a noise attenuator was cascaded with the PLL loop filter to reduce the equivalent tuning gain. The low-IF architecture allowed a discrete-step AGC that improves both tuner noise and linearity performance. Tuner gain and IF corner frequency were calibrated using replica ring oscillators that are tuned up to the onset of oscillations. The tuner specifications include: 90 dB gain range, 9 dB noise figure at max gain, +25 dBm IIP3 at min gain, 1.3degrms integrated phase noise, les50 dBc spurs, 0.7 W power consumption from dual 1.8/3.3-V supplies, and 1.8times1.2 mm ² die area     

Enhanced Bioremediation of Fuel-Oil Contaminated Soils: Laboratory Feasibility Study

In this study, microcosm experiments were conducted to evaluate the effectiveness of (1) nutrients, hydrogen peroxide (H2O2), and cane molasses addition; (2) soil washing by biodegradable surfactant [Simple Green (SG)]; and (3) soil pretreatment by Fenton-like oxidation on the bioremediation of fuel-oil contaminated soils. The dominant native microorganisms in the fuel-oil contaminated soils after each treatment process were determined via polymerase chain reaction, denaturing gradient gel electrophoresis, and nucleotide sequence analysis. Results show that approximately 32 and 56% of total petroleum hydrocarbon (TPH) removal (initial concentration of 5,000?mg?kg?1) were observed in microcosms with the addition of nutrient and cane molasses (1,000?mg?L?1), respectively, compared to only 9% of TPH removal in live control microcosms under intrinsic conditions (without amendment) after 120 days of incubation. Addition of cane molasses would cause the increase in microbial population and thus enhance the TPH degradation rate. Results also show that approximately 61% of TPH removal was observed in microcosms with the addition of H2O2(100?mg?L?1) and nutrient after 120 days of incubation. This indicates that the addition of low concentration of H2O2(100?mg?L?1) would cause the desorption of TPH from soil particles and increase the dissolved oxygen and subsequent bioremediation efficiency in microcosms. Approximately 95 and 69% of TPH removal were observed in microcosms with SG (100?mg?L?1) and higher dose of H2O2(900?mg?L?1) addition, respectively. Moreover, significant increases in microbial populations were observed and two TPH biodegraders (Pseudomonas sp. and Shewanella sp.) might exist in microcosms with SG or H2O2 addition. This indicates that the commonly used soil remedial techniques, biodegradable surfactant flushing, and Fenton-like oxidation would improve the TPH removal efficiency and would not cause adverse effects on the following bioremediation process.     

A Hardware Approach to Real-Time Program Trace Compression for Embedded Processors

Collecting the program execution traces at full speed is essential to the analysis and debugging of real-time software behavior of a complex system. However, the generation rate and the size of real-time program traces are so huge such that real-time program tracing is often infeasible without proper hardware support. This paper presents a hardware approach to compress program execution traces in real time in order to reduce the trace size. The approach consists of three modularized phases: 1) branch/target filtering; 2) branch/target address encoding; 3) Lempel-Ziv (LZ)-based data compression. A synthesizable RTL code for the proposed hardware is constructed to analyze the hardware cost and speed and typical multimedia benchmarks are used to measure the compression results. The results show that our hardware is capable of real-time compression and achieving compression ratio of 454:1, far better than 5:1 achieved by typical existing hardware approaches. Furthermore, our modularized approach makes it possible to trade off between the hardware cost (typically from 1 to 50K gates) and the achievable compression ratio (typically from 5:1 to 454:1)     

A new interactive model for improving the learning performance of back propagation neural network

The Back Propagation Neural Network (BPNN) has been used widely in construction management, but in fact, the BPNN is limited by a non-optimum weight adjustment manner and negatively influenced the convergence results. For this reason, this paper proposes the Individual Inference Adjusting Learning Rate technique (IIALR) to enhance the learning performance of the BPNN. The mechanism of the weight adjustment in the IIALR is an individual learning rate for each weight. Furthermore, this paper also establishes the Batch-Online Weight Updating Frequency mode (BOWUF) for the IIALR model, so as to adjust the connected weight of the BPNN properly and effectively. Finally, three cases are used to verify that the IIALR model can be more effective than other modifications of the BPNN. The IIALR model is conducive for assisting with the decision making process of construction management.