Virtual organizational learning in open source software development projects

We studied virtual organizational learning in open source software (OSS) development projects. Specifically, our research focused on learning effects of OSS projects and the factors that affect the learning process. The number and percentage of resolved bugs and bug resolution time of 118 SourceForge.net OSS projects were used to measure the learning effects. Projects were characterized by project type, number and experience of developers, number of bugs, and bug resolution time. Our results provided evidence of virtual organizational learning in OSS development projects and support for several factors as determinants of performance. Team size was a significant predictor, with mid-sized project teams functioning best. Teams of three to seven developers exhibited the highest efficiency over time and teams of eight to 15 produced the lowest mean time for bug resolution. Increasing the percentage of bugs assigned to specific developers or boosting developer participation in other OSS projects also improved performance. Furthermore, project type introduced variability in project team performance.     

Investigation of microbial safety of a full-scale ozonation and biological activated carbon process under high humidity and temperature conditions

Microbial safety of a full-scale ozonation and biological activated carbon (BAC) process was investigated by examining pathogens, microbial community and particle counts, with emphasis on the BAC effluent. The process is located at South China, where the average humidity and air temperature were 70-80% and 22-24 °C, respectively. A high diversity of microbial community existed on the BAC media. Three types of dominant bacteria were identified, including Chryseobacterium indologenes, Bacillus brevis and Pseudomonas stutzeri, accounting for 90-95% of total bacteria number. As to pathogenic bacteria and viruses, an opportunistic pathogen, Bacillus cereus, was detected on the BAC. Six types of invertebrates were also observed on the medium, including rotifer, cyclops, nematode, clodecera, nauplius and blood worm. Diversity and number of invertebrates in the BAC effluent were higher than those in the BAC influent. Particle counts were generally less than 50 CNT/mL, with the maximum of 500 CNT/mL during the initial filtration stage after backwashing.     

Video Error Concealment Using Spatio-Temporal Boundary Matching and Partial Differential Equation

Error concealment techniques are very important for video communication since compressed video sequences may be corrupted or lost when transmitted over error-prone networks. In this paper, we propose a novel two-stage error concealment scheme for erroneously received video sequences. In the first stage, we propose a novel spatio-temporal boundary matching algorithm (STBMA) to reconstruct the lost motion vectors (MV). A well defined cost function is introduced which exploits both spatial and temporal smoothness properties of video signals. By minimizing the cost function, the MV of each lost macroblock (MB) is recovered and the corresponding reference MB in the reference frame is obtained using this MV. In the second stage, instead of directly copying the reference MB as the final recovered pixel values, we use a novel partial differential equation (PDE) based algorithm to refine the reconstruction. We minimize, in a weighted manner, the difference between the gradient field of the reconstructed MB in current frame and that of the reference MB in the reference frame under given boundary condition. A weighting factor is used to control the regulation level according to the local blockiness degree. With this algorithm, the annoying blocking artifacts are effectively reduced while the structures of the reference MB are well preserved. Compared with the error concealment feature implemented in the H.264 reference software, our algorithm is able to achieve significantly higher PSNR as well as better visual quality.     

A qualitative study on the comfort and fit of ladies' dress shoes

The perceived differences between comfortable and uncomfortable shoes and the fit preferences in the different regions of ladies' shoes were explored. Twenty Hong Kong Chinese females participated in the study. Each participant wore and rated the different aspects of their own comfortable and uncomfortable shoes. The Wilcoxon signed rank tests showed significant differences in ten perceived characteristics between the comfortable and uncomfortable shoes. Among the ten were tactile, auditory and olfactory sensations. The ten items reliably (Cronbach alpha>0.9) distinguished between comfortable and uncomfortable shoes. There were no significant differences between comfortable and uncomfortable shoes for aesthetic-related characteristics. Further analysis on the fit ratings showed a significant impact on the fit preferences in the Toe region (p<0.0001), Metatarsophalangeal (MPJ) region (p<0.0001), Arch region (p=0.002) and Ingress/egress opening (p<0.001). Knowing the preferred type of fit can help establish a specification for comfortable shoes and also brings out the criteria that a comfortable shoe does not necessarily have the same perceived fit in every region of a shoe.     

Photocatalytic Dry Reforming of Methane Enhanced by “Dual-Path” Strategy with Excellent Low-Temperature Catalytic Performance

Dry reforming of methane (DRM), which involves the activation of inert C H bonds and CO bonds, at mild conditions is a tremendous challenge. The sluggish mobility of oxygen during the reaction is known as a key issue causing low activity and poor stability of catalysts by the coke formation. Herein, a novel Cu-CNN/Pd-BDCNN photocatalyst that is made up of “Cu-nanoparticle-loaded g-C₃N₄ nanosheets” and “Pd-nanoparticle-loaded boron-doped nitrogen-deficient g-C₃N₄ nanosheets” is reported. The existing dual-reaction-sites benefit the reactive oxygen intermediates participate in the reaction directly without distant migration. The in situ characterizations and density functional theory calculations reveal a newly dual reaction pathway through simultaneous dehydrogenation of methoxy and methyl intermediates, and demonstrate the importance of metal loading, which promote the CO₂ and CH₄ activation from both aspects of thermodynamics and kinetics. The optimized Cu-CNN/Pd-BDCNN photocatalyst displays an excellent syngas formation rate of over 800 µmol g⁻¹ h⁻¹ with H₂/CO = 1 and splendid stability in continuous flow reaction under 300 mW cm⁻² xenon lamp irradiation at room temperature. The “dual-site” and “dual-path” strategy shed light on the design of effective photocatalysts for methane dry reforming.     

Three‐dimensional vibration analysis of rectangular thick plates on Pasternak foundation

The free‐vibration characteristics of rectangular thick plates resting on elastic foundations have been studied, based on the three‐dimensional, linear and small strain elasticity theory. The foundation is described by the Pasternak (two‐parameter) model. The Ritz method is used to derive the eigenvalue equation of the rectangular plate by augmenting the strain energy of the plate with the potential energy of the elastic foundation. The Chebyshev polynomials multiplied by a boundary function are selected as the admissible functions of the displacement functions in each direction. The approach is suitable for rectangular plates with arbitrary boundary conditions. Convergence and comparison studies have been performed on square plates on elastic foundations with different boundary conditions. It is shown that the present method has a rapid convergent rate, stable numerical operation and very high accuracy. Parametric investigations on the dynamic behaviour of clamped square thick plates on elastic foundations have been carried out in detail, with respect to different thickness–span ratios and foundation parameters. Some results found for the first time have been given and some important conclusions have been drawn. Copyright © 2004 John Wiley & Sons, Ltd.     

Watermark-Induced High-Density Via Failures in Submicron CMOS Fabrication (May 2006)

High via resistance was detected in the high-density via structure in our 0.15-mum back-end-of-line (BEOL) yield monitoring test vehicle. A localized insulating layer was found on top of the plug in test vehicle causing high via resistance. The failure was attributed to watermark-induced contaminants on top of the W plug. It was shown that the failure could be avoided by eliminating watermark formation on the wafer in the post-chemical-mechanical polishing scrub process.     

Topological considerations of ATM networks

This article considers two hierarchical routing models based on the optimization of the size of topology databases and routing complexity, respectively. Some design guidelines are also suggested for an hierarchical PNNI structure of a network topology. Copyright © 1999 John Wiley & Sons, Ltd.     

The catalytic performance and characterization of a durable perovskite-type chloro-oxide SrFeO3–δClσ catalyst selective for the oxidative dehydrogenation of ethane

The catalytic performances and properties of SrFeO_3-0.190 and SrFeO_3-0.382Cl_0.443 catalysts have been investigated for the oxidative dehydrogenation of ethane (ODE). XRD results showed that both catalysts exhibited oxygen-deficient perovskite-type structures. The inclusion of chloride ions in the SrFeO_3-δlattice matrix can significantly enhance ethene selectivity and ethane conversion. The SrFeO_3-0.382Cl_0.443 catalyst showed an ethane conversion of ca. 90%, an ethene selectivity of ca. 70%, and an ethene yield of ca. 63% under the reaction conditions: C₂H₆:O₂:N₂ = 2:1:3.7, temperature 680°C, and space velocity 6000 ml h^-1 g^-1. With the increase of space velocity, ethane conversion decreased, whereas ethene selectivity increased over SrFeO_3-0.382Cl_0.443. Lifetime studies showed that the perovskite-type chloro-oxide catalyst was durable. The results of O₂-TPD and TPR experiments illustrated that the implanted chloride ions caused the oxygen nature of SrFeO_3-δ to change. By regulating the concentration of oxygen vacancies and the Fe⁴⁺/Fe ratio in this perovskite-type chloro-oxide catalyst, one can generate a durable chloro-oxide catalyst for the ODE reaction with excellent performance. This revised version was published online in August 2006 with corrections to the Cover Date.     

Defective structure, oxygen mobility, oxygen storage capacity, and redox properties of RE-based (RE = Ce, Pr) solid solutions

Defective structures, surface textures, oxygen mobility, oxygen storage capacity (OSC), and redox properties of RE_0.6Zr_0.4O₂ and of RE_0.6Zr_0.4−xY_xO₂ (RE=Ce, Pr; x=0, 0.05) solid solutions have been investigated using X-ray diffraction (XRD), temperature-programmed desorption (TPD), temperature-programmed reduction (TPR), O₂−H₂ and O₂−CO titration, ¹⁸O/¹⁶O isotope exchange, CO pulsing reaction, and X-ray photoelectron spectroscopy (XPS) techniques. The effects of doping noble metal onto RE_0.6Zr_0.4−xY_xO₂ on oxygen mobility and surface oxygen activities have also been studied. Based on the experimental outcomes, we conclude that: (i) a Pr-based solid solution has better redox behavior than a Ce-based one; (ii) incorporation of yttrium ions in the lattices of CZ and PZ solid solutions could result in an enhancement in oxygen vacancy concentration, Ce⁴⁺/Ce³⁺ and Pr⁴⁺/Pr³⁺ redox properties, lattice oxygen mobility, and oxygen storage capacity; and (iii) doping the noble metal (Rh, Pt, and Pd) onto RE-based solid solution has positive effect on the properties concerned in this work.