提高PLC性能的精密信号处理和数据转换IC

可编程逻辑控制器(PLC)是一种基于计算机的紧凑电子系统,该系统使用数字或模拟输入和输出模块控制机械、处理器和其它的控制模块.     

High-Temperature Stable IrxSi Gates With High Work Function on HfSiON p-MOSFETs

A novel 1000 degC-stable Ir_xSi gate on HfSiON is shown for the first time with full process compatibility to current very-large-scale-integration fabrication lines and proper effective work function of 4.95 eV at 1.6-nm equivalent-oxide thickness. In addition, small threshold voltages and good hole mobilities are measured in Ir_xSi/HfSiON transistors. The 1000 degC thermal stability above pure metal (900 degC only) is due to the inserted 5-nm amorphous Si, which also gives less Fermi-level pinning by the accumulated metallic full silicidation at the interface     

Optimized spatial correlations for broadband light trapping nanopatterns in high efficiency ultrathin film a-Si:H solar cells

Nanophotonic structures have attracted attention for light trapping in solar cells with the potential to manage and direct light absorption on the nanoscale. While both randomly textured and nanophotonic structures have been investigated, the relationship between photocurrent and the spatial correlations of random or designed surfaces has been unclear. Here we systematically design pseudorandom arrays of nanostructures based on their power spectral density, and correlate the spatial frequencies with measured and simulated photocurrent. The integrated cell design consists of a patterned plasmonic back reflector and a nanostructured semiconductor top interface, which gives broadband and isotropic photocurrent enhancement.     

Development of a partnering performance index (PPI) for construction projects in Hong Kong: a Delphi study

Over the past decade, research studies on benefits, critical success factors, difficulties, process, conceptual and theoretical models of construction partnering have been ubiquitous in the construction management discipline. In fact, there is adequate evidence that an increasing number of client organizations are adopting a partnering approach to undertake their building and construction projects both locally and worldwide during the last decade. With the perceived benefits that partnering brings about, research into Key Performance Indicators (KPIs) to evaluate the success of partnering projects in construction becomes vital as it can help set a benchmark for measuring the performance level of partnering projects. However, although there are some related studies and papers on this research area, few, if any, comprehensive and systematic studies focus on developing a comprehensive, objective, reliable and practical performance evaluation model for partnering projects. A model has been developed using the Delphi survey technique to objectively measure the performance of partnering projects in Hong Kong based on a consolidated KPIs' conceptual framework previously developed for partnering projects. Four rounds of Delphi questionnaire survey were conducted with 31 construction experts in Hong Kong. The results reveal that the top seven weighted KPIs to evaluate the success of partnering projects in Hong Kong were: (1) time performance; (2) cost performance; (3) top management commitment; (4) trust and respect; (5) quality performance; (6) effective communications; and (7) innovation and improvement. A statistically significant consensus on the top seven weighted KPIs was also obtained. Finally, a composite Partnering Performance Index (PPI) for partnering projects in Hong Kong was derived to provide an all‐round assessment of partnering performance. Different partnering projects can now be assessed on the same basis for benchmarking purposes. Construction senior executives and project managers can thus use the Index to measure, evaluate and improve the performance of their partnering projects to strive for construction excellence. Although the PPI was developed locally in Hong Kong, the research method could be replicated in other parts of the world to produce similar indices for international comparison. Such an extension would aid the understanding of managing partnering projects across different geographic locations.     

Influence of fruit ripeness and salt concentration on the microbial processing of Arbequina table olives

Arbequina table olives are processed as “naturally green olives”, they are directly placed in brine and fermentation starts spontaneously. Olives are harvested just before they change to ‘turning colour’. Different salt concentrations are used depending on the producer. The aim of the study was to evaluate how (i) the ripeness of the olive when it is harvested and (ii) the salt concentration of the brine influence the different microorganism populations in brine during the fermentation of Arbequina table olives.The results showed that the Enterobacteriaceae population lasted longer in black and turning colour olives than in green olives, whereas the growth of lactic acid bacteria was delayed in green olives. A higher salt concentration favoured the elimination of Enterobacteriaceae and hindered yeast growth. The main yeast species identified were Pichia anomala, Candida sorbosa and Candida boidinii, while Lactobacillus plantarum was the only lactic acid bacteria species involved in the process. In a sensory test, panellists preferred green olives and were not able to tell the laboratory-scale processed olives from a commercial sample, nor could they distinguish green olives from different brines.     

An exact procedure for planning holidays and working time under annualized hours considering cross-trained workers with different efficiencies

Annualizing working hours (AH) is a means of achieving flexibility in the use of human resources to cope with the seasonal nature of demand. Some existing planning procedures are able to minimize costs through the use of overtime and temporary workers. However, due to the great difficulty in solving the problem, it is normally assumed both that holiday weeks are fixed beforehand and that workers from different categories who are able to perform a specific type of task have the same efficiency. Often the reality is different, and thus there is a gap between academic and real problems. In the present paper, those constraints are relaxed and a much more general and true-to-life problem is solved in an exact and very efficient way.     

Intermolecular and intramolecular hydrogen bonding of poly(dimethylsiloxane)urethane‐graft–poly(methyl methacrylate) copolymers based on 2,4‐TDI and m‐XDI

In this study, poly(dimethylsiloxane)urethane–graft–poly(methyl methacrylate) (PDMS urethane–g–PMMA) copolymers with low crosslinking density were synthesized. Glass transition temperatures of the copolymers were investigated by dynamic mechanical analysis (DMA) and differential scanning calorimetry (DSC). Results confirm that PDMS urethane–g–PMMA is miscible in the 2,4‐TDI (2,4‐ toluene diisocyanate) system, whereas it is partially miscible in the m‐XDI (m‐xylene diisocyanate) system. Free, intra‐ (urethane–urethane), and inter‐ (urethane–ester) association hydrogen bonding exist in the urethane group of copolymers. The inter‐association hydrogen bonding can improve the compatibility of the copolymer components. The relationship between the frequency shift and enthalpy confirm the distribution of hydrogen bonding in the macromonomer and copolymer. Ninety percent of the hydrogen bonding is by interassociation in the 2,4‐TDI system. The intra‐association hydrogen bonding in the m‐XDI system is higher than that in the 2,4‐TDI system. Consequently, aggregation may occur easily in the siloxane‐grafted chain in the m‐XDI system. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 962–972, 2002     

Effect of cold-work on self-welding susceptibility of austenitic stainless steel (alloy D9) in high temperature flowing sodium

Self-welding susceptibility of alloy D9 (15Cr-15Ni-2Mo titanium-modified austenitic stainless steel), used as wrapper in the fuel subassemblies of sodium cooled fast reactor, was studied in flowing sodium. Specimens were tested at 823 K in annealed and in 20% cold-worked condition up to a maximum contact stress of 24.5 MPa and maximum duration of 9 months. The results showed that the annealed alloy D9 showed good resistance to self-welding in all the tests. But 20% cold-worked alloy D9 got self-welded in all the tests except in the test carried out for 3 months duration indicating that tests conducted at high contact stresses and long duration reduce the resistance of the steel to self-weld. Microstructural changes observed in the cold-worked alloy D9 at the location of contact between the mating surfaces indicate dynamic recovery resulting from high contact stress and temperature facilitating self-weld.     

On Beck's problem

Based on the concept of internal constraint the discrete Beck's problem is solved by means of static methods.     

Field Pullout Testing and Performance Evaluation of GFRP Soil Nails

Glass fiber–reinforced polymer (GFRP) materials provide practical solutions to corrosion and site-maneuvering problems for civil infrastructures using conventional steel bars as reinforcements. In this study, the feasibility of using GFRP soil nails for slope stabilization is evaluated. The GFRP soil nail system consists of a GFRP pipe installed by the double-grouting technique. Two field-scale pullout tests were performed at a slope site. Fiber Bragg grating (FBG) sensors, strain gauges, linear variable displacement transformers (LVDTs), and a load cell were used to measure axial strain distributions and pullout force-displacement relationships during testing. The pullout test results of steel soil nails at another slope site are also presented for comparison. It is proven that the load transfer mechanisms of GFRP and steel soil nails have certain difference. Based on these test results, a simplified model using a hyperbolic shear stress-strain relationship was developed to describe the pullout performance of the GFRP soil nail. A parametric study was conducted using this model to study some factors affecting the pullout behavior of GFRP soil nails, including nail diameter, shear resistance of soil-grout interface, and ratio of interface shear coefficient to the Young’s modulus of the nail. The results indicate that the GFRP soil nail may exhibit excessive pullout displacement and thus a lower allowable pullout resistance than with the steel soil nail.