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Reliability is an essential scientific and technological domain intrinsically linked with system integration. Nowadays, semiconductor industries are confronted with ever-increasing design complexity, dramatically decreasing design margins, increasing chances for and consequences of failures, shortening of product development and qualification time, and increasing difficulties to meet quality, robustness, and reliability requirements. The scientific successes of many micro/nano-related technology developments cannot lead to business success without innovation and breakthroughs in the way that we address reliability through the whole value chain. The aim of reliability is to predict, optimize and design upfront the reliability of micro/nanoelectronics and systems, an area denoted as ‘Design for Reliability (DfR)’. While virtual schemes based on numerical simulation are widely used for functional design, they lack a systematic approach when used for reliability assessments. Besides this, lifetime predictions are still based on old standards assuming a constant failure rate behavior. In this paper, we will present the reliability and failures found in solid-state lighting systems. It includes both degradation and catastrophic failure modes from observation towards a full description of its mechanism obtained by extensive use of acceleration tests using knowledge-based qualification methods. A use case will be presented in more details.

To develop an ultra-high temperature resistant coating for niobium alloy, a new type of 10%ZrB2 + 5%YSZ-modified Si-Mo-18%W coating with a boride diffusion barrier was prepared by a novel three-step method. The coating with NbB2-Nb3B2 diffusion barrier can effectively protect Nb521 alloy at 1850 °C for more than 8 h, while the life of coating without diffusion barrier was only 3.5 h. The excellent performance of the coating was attributed to the present of diffusion barrier and formation of self-healing SiO2-B2O3-ZrSiO4-ZrO2 oxide scale. The diffusion barrier can effectively hinder mutual diffusion of coating and substrate, and reduce inward consumption of silicon element.

A new YSZ (yttria stabilized zirconia) modified silicide coating was prepared on Mo-based alloy through a two-step process, including spraying of Si-Mo-YSZ slurry followed by reaction sintering. Microstructure and oxidation behavior of the coatings with different YSZ content (0, 5, 10 and 15%) were studied. The coating consists of a MoSi2-ZrSi2-SiO2 outer layer and a MoSi2 inner layer. The 10% YSZ modified coating possessed the best oxidation protection at ultra-high temperatures and, for the coating, the mass gain was 0.96 mg/cm2 after being exposed at 1725 °C in air for 22 h, whereas the uncoated Mo-based alloy completely ablated for 0.35 h. The excellent oxidation resistance of the silicide coating was attributed to the compact and self-healing SiO2 protective scale, which contained the dispersed ZrO2 and ZrSiO4. Keywords: Molybdenum-based alloy, Silicide coating, Oxidation, YSZ, MoSi2, Ultra-high temperature

The cobalt coating with an average thickness of 15–20 nm was uniformly plated on the surface of ultra-fine WC powders by electroless plating in the present work. The effects of electroless plating condition parameters on the deposition rate were studied. It was found that the deposition rate increased with the increase of CoSO4·7H2O content, pH value, complexing agent concentration, and bath temperature, while decreased with the increase of reducing agent (NaH2PO2·H2O) concentration. Furthermore, the cobalt deposition rate empirical equation and activation energy were determined. The results show that the activation energy (Ea) for the electroless cobalt on WC substrates is approximately 54.65 kJ/mol.

Deformation twinning in a medium carbon steel containing ferrite and pearlite under shock compression is investigated below and above the α–e phase transition stress (σT), within a peak stress range of 10–20 GPa. Free surface velocity histories are measured to obtain the Hugoniot elastic limit (2.7 GPa), σT (13.3 GPa) and bulk plastic strain. Postmortem samples are characterized with electron backscatter diffraction and transmission electron microscopy. Below σT, all the {112}〈111〉 twinning activation in ferrite and pearlite follows the Schmid law, while above σT, approximately 1/6 of the activation deviates from the law. Propagation of the {112}〈111〉 twins in pearlite depends on the orientation of the activated twinning plane relative to cementite lamellae. With increasing peak stress, the {112}〈111〉 twin area fraction in ferrite/pearlite increases greatly/slightly; the {112}〈111〉 twin area fraction in ferrite is about 7 times that of pearlite. The {332}〈113〉 twins can only form above σT, favoring ferrite over pearlite, and are likely to be the secondary twins originated at the {112}〈111〉 twin boundaries.

The stress-aging method is proposed to improve the dimensional stability of Al-Cu-Mg (2024 aluminum) alloy. Both the reduction of residual stress and the acceleration of precipitates are investigated during the stress-aging process. It is observed that some S′ particles precipitate in the alloy during stress-aging. With the external stress increase to 100 MPa, the residual stress and thermal strain (ɛ c ) decrease, while the micro-yield strength increases significantly. This is attributed to that the dislocations are effectively pinned by the uniformly distributed precipitates and the stored elastic energy diminishes remarkably, which leads to a considerable improvement of the dimensional stability of 2024 aluminum alloy. However, when further increases the external stress to 150 MPa, due to the coarsened precipitates, the residual stress and thermal strain increase, while the micro-yield strength decreases slightly.

Ultra-fine WC/Co composite powders were prepared by electroless plating in this study. The Co layers with an average thickness of 50–100 nm were uniformly and completely covered on raw WC particles with a diameter of 0.3–0.5 µm. The influences of electroless plating conditions on the composites were investigated. The Co layer covering on WC particles was controlled by the content of CoSO 4 ·7H 2 O, pH value and bath temperature. With increasing the content of CoSO 4 ·7H 2 O up to 25 g/L, both the weight gain and the plating rate markedly increased. However, when the content of CoSO 4 ·7H 2 O further increased to 30 g/L, while the weight gain displayed a slight decrease, the plating rate continued to increase moderately. Moreover, with the increase of pH value from 9.5 to 11, both the weight gain and the reaction time decreased. Furthermore, the plating rate exhibited an exponential relationship with the bath temperature. When the pH value, bath temperature and the concentration of CoSO 4 ·7H 2 O are 10, 80 °C and 25 g/L respectively, the weight gain of Co-coated WC composite powders is 185.1 mg/g.

Due to the excellent structural and functional properties, such as low density, high fracture toughness and fatigue strength, Al-Cu-Mg (2024 aluminum) alloy has become an attractive light weight material for inertial instruments and aerospace applications. However, it has relatively low dimensional stability. The aim of this investigation is to enhance the dimensional stability of 2024 aluminum alloy via two-stage aging method, and identify the precipitation behavior and the underlying stabilizing mechanisms of 2024 aluminum alloy. When the second aging time was 24 h, the uniformly distributed precipitates could effectively pin the dislocations and impede their movement. This leaded to a significant improvement of the micro-yield strength and the thermal strain in the 2024 aluminum alloy, and thus the dimensional stability of the alloy increased.

Ozone has become the main factor affecting the air quality in the Pearl River Delta (PRD) in recent years, and a clear understanding source of ozone pollution is a top priority of ozone pollution prevention. However, the vertical distribution of tropospheric ozone in the PRD is poorly understood. Based on daily ozone sounding data obtained in Yangjiang (111°58'00" E, 21°50'00" N), Guangdong Province, from 18 November tjo 3 December 2013, the detailed vertical distribution of tropospheric ozone and its influencing factors were determined and compared with weekly autumn ozone profile data obtained at the Hong Kong Observatory (HKO) and corresponding tropospheric column ozone (TCO) datasets from the Ozone Monitoring Instrument (OMI) and Microwave Limb Sounder (MLS) onboard satellite AURA. Overall, the ozone profiles observed in Yangjiang are in accordance with those of the HKO in terms of the vertical structure. The TCO values are 34.2 ± 4.0 and 34.3 ± 4.6 DU, respectively, that are, 4 DU higher than those of satellite data, indicating that the OMI/MLS product underestimates the TCO level in the PRD region. The Yangjiang ozone profiles indicate significant variations in the ozone vertical structure and concentration during the observation period. A significant ozone peak permanently occurs in the lower troposphere at 1.1 ± 0.4 km above the surface. The vertical structural difference is mainly reflected in the presence of low-ozone strata (below 30 ppbv) near the tropopause and ozone peaks and high-ozone stratification in the middle and upper troposphere. The average ozone peak concentrations in the lower, middle, and upper troposphere are 65.2 ± 9.9, 57.8 ± 7.7, 71.8 ± 13.6 ppbv, respectively, which are higher than the average ground-level ozone concentration (48.9 ± 9.4 ppbv). Based on the analysis of the profile characteristics, weather conditions, and backward trajectories, it can be concluded that the low-ozone strata near the tropopause are caused by the regional transport of the tropical air mass from the tropical cyclone storm area. Potential vorticity analysis shows that stratosphere-troposphere exchange (STE) is the main reason for the formation of the ozone peaks and its varying concentrations in the middle and upper troposphere. Photochemical reactions represent the main factor affecting the ozone concentration in the lower troposphere. The STE is also an important factor affecting the ozone in the lower troposphere, leading to an increase in the surface ozone concentration by ~10.9 ppbv.

Due to excellent chemical stability, high rigidity, superior corrosion and wear resistance, aluminum oxynitride (AlON) has been considered as one of most promising candidate ceramic materials in high-performance structural, advanced abrasives and refractory fields. However, it usually exhibited relatively low flexural strength and poor fracture toughness. The study is aimed to develop silicon carbide (SiC) and zirconium nitride (ZrN) nano-particulate reinforced AlON composites with improved mechanical properties and fracture resistance via a hot-press sintering process. It was found that the addition of ZrO 2 nanoparticles would be transformed into ZrN during sintering. Due to the pinning effect of SiC and ZrN nano-particles positioned at grain boundaries of micro-sized AlON particles, the presence of SiC and ZrN nano-particles resulted in the reduction of both porosity and grain size, and a change of fracture mode from intergranular cracking in AlON to intragranular cracking in composites. With presence of 8 wt% SiC and 5.2 wt% ZrN nano-particles, the relative density, microhardness, Young’s modulus, flexural strength and fracture toughness increased. Different toughening mechanisms including crack bridging, crack branching and crack deflection were observed, thus effectively increasing the crack propagation resistance and leading to a considerable improvement in flexural strength and fracture toughness.

MoSi2-NbSi2 coating and Ce-modified MoSi2-NbSi2 coating were prepared on Nb-alloy through a new two-step process, including molybdenum slurry spraying and halide-activated pack cementation. The bare alloy was pulverized after oxidation at 1600 °C for 15 min. The both two coated samples have the effective protection for 24.7 h and 28.5 h with the weight gain rate of 3.578 and 2.947 mg2 cm−4 h−1, respectively. Ce-modified samples show better performance due to Ce has the ability of grain refinement. The reasons for the excellent performance are the good matching between MoSi2 outer layer and NbSi2 inner layer and the continuous SiO2 oxide scale.

Aluminum oxynitride (AlON) exhibits excellent stability, chemical and mechanical properties. Corrosion resistance to molten steel is an important performance index of ceramic refractories. While silicon carbide (SiC) particles have been proven to improve the mechanical properties and thermal shock resistance of AlON ceramic, the corrosion of AlON and SiC–AlON composites by molten steel were unknown. The aim of this investigation was to evaluate the corrosion resistance to molten steel and identify the underlying mechanisms of AlON ceramic and 8 wt% SiC–AlON composites at the temperature of 1550 °C for 30 min. Due to the reaction between AlON and molten steel, a solid product of Al 2 O 3 is detected in the corrosion region. Besides, some round shaped pores form and increase toward the sample surface in the corrosion region. The thickness of corrosion region of AlON ceramic is about 150 μm, indicating that the AlON ceramic has an excellent corrosion resistance to molten steel. However, the corrosion resistance of 8 wt% SiC–AlON composites to molten steel can be characterized with a penetrated depth of approximately 250 μm. This is mainly attributed to the thermal dissociation of SiC and the reaction between SiC and molten steel.

Aluminum oxynitride (AlON) has been considered as a potential ceramic material for high-performance structural and advanced refractory applications owing to its excellent stability and mechanical properties such as high rigidity and good chemical stability. Thermal shock resistance is a major concern and an important performance index of refractories and high-temperature ceramics. While zirconium nitride (ZrN) particles have been proven to improve mechanical properties of AlON ceramic, the thermal shock behavior has not been evaluated yet. The aim of this investigation was to identify the thermal shock resistance and underlying mechanisms of hot-pressed 2.7% ZrN–AlON composites by a water-quenching technique over a temperature range between 225 °C and 275 °C. The residual strength and Young's modulus after thermal shock decreased with increasing temperature range and thermal shock times due to large temperature gradients and thermal stresses caused by abrupt water-quenching. The presence of nano-sized ZrN particles exhibited a positive effect on the improvement of both residual strength and critical temperature difference of AlON ceramic due to the toughening effects, the higher thermal conductivity of ZrN, the refined grain size and the reduction of porosity. Different toughening mechanisms including crack deflection, crack bridging and crack branching were observed during thermal shock experiments, thus effectively enhancing the crack initiation and propagation resistance and leading to a considerable improvement in thermal shock resistance in the ZrN–AlON composites.

A suspension with good rheology and high stability is crucial for slip casting and gelcasting technology. However, a mixed suspension from two or more different powders usually has bad rheology because of the easy agglomeration of mixed powders caused by the attractive force between the powders with heterocharges. We studied the surface modification of the each single-component powders (SiC, Al2O3, ZrO2(3Y) powders) and the SiC-Al2O3-ZrO2(3Y) mixed powders to increase the repulsive force by adjusting the pH value and adding polyacrylic acid (PAA) as dispersant. The PAA addition effects on the SiC-Al2O3-ZrO2(3Y) mixture were investigated in terms of zeta potential, pH range for heterocharge region, dispersion of the mixed powders and rheology of the mixed slurry based on the study of each unary suspensions. The results show that before surface modification the SiC-Al2O3-ZrO2(3Y) mixed powders were agglomerated severely because they were in the heterocharge region with a broad pH range from 3.5 to 8.25, while after surface modification (pH = 10.5, PAA = 0.8wt%) the heterocharge region was narrowed with a relatively narrower pH range from 2.6 to 3.7. The mixed powders with homocharges were dispersed well because of the great electrostatic repulsive force and steric hindrance offered by PAA and the mixed suspensions had favorable rheology.

The stress–strain properties of eutectic Sn-Pb and lead-free solders at strain rates between 0.1 s−1 and 300 s−1 are required to support finite-element modeling of the solder joints during board-level mechanical shock and product-level drop-impact testing. However, there is very limited data in this range because this is beyond the limit of conventional mechanical testing and below the limit of the split Hopkinson pressure bar test method. In this paper, a specialized drop-weight test was developed and, together with a conventional mechanical tester, the true stress–strain properties of four solder alloys (63Sn-37Pb, Sn-1.0Ag-0.1Cu, Sn-3.5Ag, and Sn-3.0Ag-0.5Cu) were generated for strain rates in the range from 0.005 s−1 to 300 s−1. The sensitivity of the solders was found to be independent of strain level but to increase with increased strain rate. The Sn-3.5Ag and the Sn-3.0Ag-0.5Cu solders exhibited not only higher flow stress at relatively low strain rate but, compared to Sn-37Pb, both also exhibited higher rate sensitivity that contributes to the weakness of these two lead-free solder joints when subjected to drop impact loading.

Several links of water resources allocation is introduced in city, on the basis of supply analysis, water demand prediction and supply-demand balance analysis, the frame of water resources allocation and the structure of urban return water are put forward, in view of the present research situation , the urban return water mechanism is promoted. The study not only provide theoretical reference to return water problems base on water resources allocation, but also give important guiding significance to the rational development and utilization of water resources in city.

Using data collected with the BESII detector at Beijing Electron-Positron Collider, the measurements of relative branchin- fractions for seven Cabibbo-suppressed hadronic weak decays D-0 -> K-K+, pi-pi(+), pi(-)pi(+)pi(-) and pi-pi(+)pi(-), D-divided by -> (K) over bar K-0(divided by), K-K+pi(+) and pi(-),pi(+pi+) are presented. (c) 2005 Elsevier B.V. All rights reserved.

The decay psi' + pi(+)pi(-)pi(0) is analyzed using a sample of 14 million psi' events taken with the BESII detector at the BEPC, and the branching fraction is measured to be B(psi' -> pi(+)pi(-)pi(0)) = (18.1 +/- 1.8 +/- 1.9) x 10(-5). A partial wave analysis is carried out using the helicity amplitude method. psi' -> rho(770)pi is observed, and the branching fraction is measured to be B(psi' -> rho(770)pi) = (5.1 +/- 0.7 +/- 1.1) x 10(-5), where the first error is statistical and the second one is systematic. A high mass enhancement with mass around 2.15 GeV/c(2) is also observed. Attributing this enhancement to the p(2150) resonance, the branching fraction is measured to be B(psi' -> rho(2150)pi -> pi(+)pi(-)pi(0)) = (19.4 +/- 2.5(-3.4)(+11.5)) x 10(-5). The results will help in the understanding of the longstanding "rho pi puzzle" between J/psi and psi' hadronic decays. (c) 2005 Elsevier B.V. All rights reserved.

A partial wave analysis is presented of J/psi --> phipi(+)pi(-) and phiK(+)K(-) from a sample of 58M J/psi events in the BES II detector. The f(0)(980) is observed clearly in both sets of data, and parameters of the Flatte formula are determined accurately: M = 965 +/- 8(stat) +/- 6(syst) MeV/c(2), g(1) = 165 +/- 10 +/- 15 MeV/c(2), g(2)/g(1) = 4.21 +/- 0.25 +/- 0.21. The phipipi data also exhibit a strong pipi peak centred at M = 1335 MeV/c(2). It may be fitted with f(2)(1270) and a dominant 0(+) signal made from f(0)(1370) interfering with a smaller f(0)(1500) component. There is evidence that the f(0)(1370) signal is resonant, from interference with f(2)(1270). There is also a state in pipi with M = 1790(-30)(+40) MeV/c(2) and Gamma = 270(-30)(+60) MeV/c(2); spin 0 is preferred over spin 2. This state, f(0)(1790), is distinct from f(0)(1710). The phiK (K) over bar data contain a strong peak due to f(2)'(1525). A shoulder on its upper side may be fitted by interference between f(0)(1500) and f(0)(1710). (C) 2004 Elsevier B.V. All rights reserved.

New data are presented on J/psi --> omegaK(+)K(-) from a sample of 58M J/psi events in the upgraded BES II detector at the BEPC. There is a conspicuous signal for f(0)(1710) --> K+K- and a peak at higher mass which may be fitted with f(2)(2150) --> K (K) over bar. From a combined analysis with omegapi(+)pi(-) data, the branching ratio BR(f(0)(1710) --> pipi)/BR(f(0)(1710) --> K (K) over bar) is < 0.11 at the 95% confidence level. (C) 2004 Elsevier B.V. All rights reserved.

The cross sections for D 0 D ¯ 0 and D + D − production at 3.773 GeV have been measured with BES-II detector at BEPC. These measurements are made by analyzing a data sample of about 17.3 pb −1 collected at the center-of-mass energy of 3.773 GeV. Observed cross sections for the charm pair production are radiatively corrected to obtain the tree level cross section for D D ¯ production. A measurement of the total tree level hadronic cross section is obtained from the tree level D D ¯ cross section and an extrapolation of the R u d s below the open charm threshold.

Using a sample of 58 million J/psi events recorded in the BESII detector, the decay J/psi --> omegapi(+)pi(-) is studied. There are conspicuous omegaf(2)(1270) and b(1)(1235)pi signals. At low pipi mass, a large, broad peak due to the sigma is observed, and its pole position is determined to be (541 +/- 39) - i (252 +/- 42) MeV from the mean of six analyses. The errors, which are dominated by the systematic errors, cover the statistical and systematic errors in the six analyses, as well as the observed variation of the six analyses. (C) 2004 Elsevier B.V. All rights reserved.

Using a sample of 58×10 6 J / ψ events collected with the BESII detector, radiative decays J / ψ → γγV , where V = ρ or φ , are studied. A resonance around 1420 MeV/ c 2 ( X (1424)) is observed in the γρ mass spectrum. Its mass and width are measured to be 1424±10(stat)±11(sys) MeV/ c 2 and 101.0±8.8±8.8 MeV/ c 2 , respectively, and its branching ratio B ( J / ψ → γX (1424)→ γγρ ) is determined to be (1.07±0.17±0.11)×10 −4 . A search for X (1424)→ γφ yields a 95% C.L. upper limit B ( J / ψ → γX (1424)→ γγφ ) −4 .

The mechanisms of statins relieving the no-reflow phenomenon and the effects of single-dose statins on it are not well known. This study sought to investigate the effects of inflammation on the no-reflow phenomenon in a rabbit model of acute myocardial infarction and reperfusion (AMI/R) and to evaluate the effects of single-dose atorvastatin on inflammation and myocardial no-reflow. Twenty-four New Zealand white male rabbits (5-6 months old) were randomized to three groups of eight: a sham-operated group, an AMI/R group, and an atorvastatin-treated group (10 mg/kg). Animals in the latter two groups were subjected to 4 h of coronary occlusion followed by 2 h of reperfusion. Serum levels of interleukin (IL)-6 were measured by enzyme-linked immunosorbent assay. The expression of interferon gamma (IFN-γ) in normal and infarcted (reflow and no-reflow) myocardial tissue was determined by immunohistochemical methods. The area of no-reflow and necrosis was evaluated pathologically. Levels of serum IL-6 were significantly lower in the atorvastatin group than in the AMI/R group (P90% of LA). There was no significant difference in the area of no-reflow between the small (61.40% of LA) and large groups (69.87% of LA; P>0.05). Single-dose atorvastatin protected against inflammation and myocardial no-reflow and reduced infarct size during AMI/R in rabbits. No-reflow was not dependent on the reduction of infarct size.

The process J/\psi --> p \bar{p} is studied using 57.7 X 10^6 J/\psi events collected with the BESII detector at the Beijing Electron Positron Collider. The branching ratio is determined to be Br(J/\psi --> p \bar{p})=(2.26 +- 0.01 +- 0.14) X 10^{-3}, and the angular distribution is well described by \frac{dN}{d cos\theta_p}=1+\alpha\cos^2\theta_p with \alpha = 0.676 +- 0.036 +- 0.042, where \theta_p is the angle between the proton and beam directions. The value of \alpha obtained is in good agreement with the predictions of first-order QCD.