Application of the blind source separation method to feature extraction of machine sound signals

As the result of vibration emission in air, a machine sound signal carries important information about the working condition of machinery. But in practice, the sound signal is typically received with a very low signal-to-noise ratio. To obtain features of the original sound signal, uncorrelated sound signals must be removed and the wavelet coefficients related to fault condition must be retrieved. In this paper, the blind source separation technique is used to recover the wavelet coefficients of a monitored source from complex observed signals. Since in the proposed blind source separation (BSS) algorithms it is generally assumed that the number of sources is known, the Gerschgorin disk estimator method is introduced to determine the number of sound sources before applying the BSS method. This method can estimate the number of sound sources under non-Gaussian and non-white noise conditions. Then, the partial singular value analysis method is used to select these significant observations for BSS analysis. This method ensures that signals are separated with the smallest distortion. Afterwards, the time-frequency separation algorithm, converted to a suitable BSS algorithm for the separation of a non-stationary signal, is introduced. The transfer channel between observations and sources and the wavelet coefficients of the source signals can be blindly identified via this algorithm. The reconstructed wavelet coefficients can be used for diagnosis. Finally, the separation results obtained from the observed signals recorded in a semi-anechoic chamber demonstrate the effectiveness of the presented methods .     

A Shortcut Method for Estimating the HETP of Structured Packed Distillation Columns at Elevated Pressure

A shortcut model is developed for predicting the HETP of a structured packed distillation column operating at elevated pressure. The proposed model incorporates the geometrical parameters of the packing, physical properties of the vapor and liquid phases, and the hydrodynamics of the two‐phase flow. The proposed model is tested and validated by comparing the predicted results with the present experimental data and some published HETP data. The results show that the proposed model can predict the experimental data with a deviation smaller than 20 %.     

Self-reinforced materials based on aluminum nitride

Powder Metallurgy and Metal Ceramics -     

Designing screens for people to use easily

The use of interactive computer systems is expanding rapidly. In many applications users can communicate directly with computer-based systems through an interactive dialogue at a display terminal. However, this direct form of communication has created problems. Whereas early users of on-line systems were skilled computer professionals, today's users may have little or no training in computer technology. How then does this group communicate effectively with a computer systems?

The answer is that many users communicate only with considerable difficulty. The result is that the effectiveness of many systems is very much less than expected. The reason for this is simple: these systems are not very good at communicating with their users.

The most common communications bridge between a person and a computer system is a display screen. A well-designed screen format can enhance user productivity, eliminate or reduce user input errors, and promote end user satisfaction. A poorly designed screen has the opposite effect: it will decrease human processing speed, provoke user mistakes, and complicate computer operations.

Screen design requires the same care as designing the overall application. It employs the same techniques as planning and preparing good user documents. Screens, like documents, must be easy to understand and easy to use. To achieve these objectives, screen designers must make good choices regarding three ease-of-use parameters: format; screen content and layout; and style. This paper describes how standards may be established for each of these parameters in a proposed application or system. Futher, an interactive tutorial computer program has been developed (using Bricklin's DEMO program) which may be used to illustrate the application of these standards.     

Nucleotide sequence and genome structure of mink enteritis virus

Diabetes mellitus is a common disease. It affects multiple organ systems. Adverse effects of hyperglycemia on infection, fracture healing, and bone remodeling have been recently reported. This study was conducted to evaluate the clinical and radiographic results of 93 total hip arthroplasties in 78 consecutive patients with diabetes. All femoral components were cemented using contemporary cementing techniques. Prophylactic antibiotics were given in each case. The mean follow-up period was 4.1 years (range, 2-6.5 years). Ninety-six percent of the hips were rated excellent or good. Radiolucencies were observed in only 3.7% of the stems, while 22.2% of the cups showed radiolucencies. There was a 4% revision incidence. There was no postoperative infection in this series--a distinct improvement from previously reported series. However, complications remained high at 24.3%. The most frequent complication was urinary tract infection (14.2%). The most serious complication was myocardial infarction. The authors believe total hip arthroplasty can be safely performed in patients with diabetes, provided that adequate medical and follow-up evaluations are performed. The medium-term clinical and radiographic follow-up evaluations are not inferior to reported series in patients without diabetes.     

Biofilm adaptation to sulfate reduction in anaerobic immobilized biomass reactors sujected to different COD/sulfate ratios.

Various aspects of biofilm adaptation to sulfate reduction in horizontal-flow anaerobic immobilized biomass (HAIB) reactors subjected to increasing sulfate concentrations and different COD/sulfate ratios are presented and discussed. Four bench-scale HAIB reactors filled with vegetal carbon (R1 and R2) and polyurethane foam matrices (R3 and R4) were utilized. Influent sulfate concentrations ranging from 500 to 3000 mg/L were applied at COD/sulfate ratios ranging from 5.0 to 1.7. Reactors R1 and R4 were operated with higher sulfate loads than those applied to R2 and R3. For the same COD/sulfate ratio, the highest sulfate reduction efficiency (approximately 80%) was displayed by the vegetal carbon reactor (R2) subjected to low sulfate loads. According to the results of our molecular biology analyses, the different support materials provided different biomass colonization conditions. The lowest diversity of sulfate-reducing bacteria was found in the HAIB filled with polyurethane foam matrices operating with high sulfate loads.     

Nonequilibrium nonstoichiometry in ionic compounds

Ionic substances under normal conditions are stoichiometric compounds with phase diagrams featuring no homogeneity regions. Crystals grown under nonequilibrium conditions, in particular, under significant centrifugal acceleration, are characterized by nonstoichiometric compositions (e.g., K_2−x Br_1.07). In this way, it is possible to obtain nonequilibrium nonstoichiometric ionic compounds possessing certain homogeneity regions. Nonstoichiometric crystals of KCl, KBr, and KI grown under various accelerations ranging within (1.3–100.0)×10³ g exhibit insignificant variations in the lattice constants and a significant increase in micro-hardness with acceleration.