Parameter identification of the fatigue-testing rig

In this paper the dynamic parameter identification of the novel fatigue-testing rig is presented. The applied identification method assumes a priori a simple dynamical model for which parameters are identified through free and forced vibration tests. The rig is comprised of two base excited oscillators providing the dynamic excitation for a fatigue sample and two pneumatic actuators preventing a loss of contact between the oscillators and the sample. The actuators introduce strong nonlinearities. All parameters of the system apart from the pneumatic actuators identified through the free vibration tests using the linear model were in a good agreement with those obtained by the frequency analysis. Two models, a linear and the nonlinear with Coulomb friction, were dynamically interrogated by a random excitation. It was shown that the stiffness coefficient a, increases linearly with the pressure in the pneumatic cylinders, and the viscous damping coefficient b increases quadratically with the air pressure in the pneumatic cylinders. The predicted responses for the linear and nonlinear models correlate well with the experimental data.     

重新定义良好的生活

为了亚洲的明天,现有的思维模式和发展途径必须有所改变,并且要迅速改变。政府的努力必须与商界和群众的教育相结合,对环境教育的共识应成为发展和经济繁荣的先决条件,同时,文章指出：发展是亚洲之梦,但不能使环境与发展分离,“快乐主义”将进一步加速环境的恶化,如果对现有的工业化进程不进行及时的反思,那么对亚洲自然资源的破坏所造成的伤害将会继续被工业化的恶性循环所驱使。     

Did the CIE get it right? A critical test of the CIE color domains for signal lights

Since 1951, the Commission Internationale de L'Eclairage (CIE) has provided influential guidance on the choice of the most suitable colors for colored signal lights. In 1994, the CIE reviewed its 1975 recommendations for signal colors and has recently revised them. These revised recommendations have now been published as a CIE standard. This article reports an experiment designed to test those recommendations and to provide data on the reliability of signal color recognition under a range of conditions. Thirty young subjects (aged 18–28 years) and thirty older subjects (aged 50–64 years) named the colors of lights, the colors of which were located on or close to the color boundaries defined by the CIE for red, yellow, white, green, and blue colors. The angular diameter of the light was one min of arc. In a second experiment, half the subjects named the colors of the lights when the angular diameter was 5 min of arc. Observations were made under both dark and light adaptation. Red signals, especially those located in the CIE Class A domain, were reliably recognized under all conditions. Yellow near the red boundary of the CIE yellow domain tended to be confused with red, especially under dark adapted conditions at low signal illuminances. White was not a reliable signal color and was often confused with yellow, except for a white located near the blue boundary of CIE white. Green colors located near the blue boundary of the CIE color domain for green were less reliably recognized than those of longer dominant wavelength. Blue signal colors located within the CIE Class A blue domain were more reliable than expected, except at very low signal illuminances. There were significant differences in the performance of older compared to younger subjects, some of which can be explained by color shifts occurring as the result of the yellowing of the lens of the eye with age. © 2001 John Wiley & Sons, Inc. Col Res Appl, 26, 109–122, 2001     

Accelerated start-up and enhanced granulation in upflow anaerobic sludge blanket reactors

In the present study, the effects of a cationic polymer on reactor start-up and granule development were evaluated. A control reactor R1 was operated without adding polymer, while the other five reactors designated R2, R3, R4, R5 and R6 were operated with different polymer concentrations of 20, 40, 80, 160 and 320 mg/L, respectively. Experimental results demonstrated that adding the polymer at a concentration of 80 mg/L markedly accelerated the start-up time. The time required to reach stable treatment at an organic loading rate (OLR) of 4 g COD/L.d was reduced by approximately 50% in R4 as compared with the control reactor. The same reactor with 80 mg/L polymer was able to achieve an OLR of 12 g COD/L.d after 59 days of operation, while R1, R2, R3, R5 and R6 achieved the same loading rate at much longer period of 104, 80, 69, 63 and 69 days, respectively. Comparing with the control reactor, the start-up time of R4 was shortened markedly by about 43% at this OLR, while other reactors also recorded varying degree of shortening. Monitoring on granule development showed that the granule formation was accelerated by 30% from the use of the appropriate dosage of polymer. Subsequent granules characterization indicated that the granules developed in R4 with 80 mg/L polymer exhibited the best settleability, strength and methanogenic activity at all OLRs. The organic loading capacities of reactors were also increased by the polymer addition. The maximum organic loading of the control reactor was 24 g COD/L.d, while the polymer-assisted reactor added with 80 mg/L polymer attained a markedly increased organic loading of 40 g COD/L.d. The laboratory results obtained demonstrated that adding the cationic polymer could result in shortening of start-up time and enhancement of granulation, which in turn lead to improvement in organics removal efficiency and loading capacity of the UASB system.     

Porous Quaternary Al0.1In0.1Ga0.8N Film Formation via Photoelectrochemical Etching in HF:C2H5OH Electrolyte

Pore formation in AlInGaN films using photoelectrochemical etching in different volume ratios of hydrofluoric acid:ethanol solution (1:1, 1:2, 1:3, and 1:4) has been investigated structurally, morphologically, and optically. A significant increase in root mean square roughness and photoluminescence intensity in AlInGaN film etched in 1:1 solution has yielded the highest pore density and the largest average pore size in the film. Moreover, the acquisition of the lowest total dislocation density as well as the largest in‐plane biaxial stress relaxation in the film suggested potential use of the porous film as a template to grow subsequent layers for development of light‐emitting diodes.     

The development of GRAMSKIL: A call grammar program for learners of English as a Second Language

To improve the grammatical skills of university-level students in an English as a Second Language (ESL) environment, the authors created a prototype software called GRAMSKIL. GRAM- SKIL differs from the current trend of software development in computer assisted language learning in two ways. Firstly, our program aims to develop grammatical competence instead of communicative competence in ESL learners. Secondly, it adopts the not-so-common approach of using a general purpose software tool—dBase III—to produce the program. GRAMSKIL uses the programming facility of dBase III to design menu-driven tasks which are user-friendly, and so computer novices can run the program without having to learn to run the database package. Moreover, GRAMSKIL allows teachers with little knowledge of database management systems to create their own database or modify the data to tailor them to the needs of their learners.     

Tooth segmentation of dental study models using range images

The accurate segmentation of the teeth from the digitized representation of a dental study model is an important component in computer-based algorithms for orthodontic feature detection and measurement and in the simulation of orthodontic procedures such as tooth rearrangement. This paper presents an automated method for tooth segmentation from the three-dimensional (3-D) digitized image captured by a laser scanner. We avoid the complexity of directly processing 3-D mesh data by proposing the innovative idea of detecting features on two range images computed from the 3-D image. The dental arch is first obtained from the plan-view range image. Using the arch as the reference, a panoramic range image of the dental model can be computed. The interstices between the teeth are detected separately in the two range images, and results from both views are combined for a determination of interstice locations and orientations. Finally, the teeth are separated from the gums by delineating the gum margin. The algorithm was tested on 34 dental models representing a variety of malocclusions and was found to be robust and accurate.     

Survival and recovery of Listeria monocytogenes on ready-to-eat meats inoculated with a desiccated and nutritionally depleted dustlike vector

Dust from construction was theorized to serve as a vector for L. monocytogenes transmission to ready-to-eat (RTE) meats after heat processing but before packaging. A five-strain Listeria monocytogenes culture including serotype 4b was continually stressed on a sand vector under four sets of nutritionally depleted and dry conditions to simulate postprocessing contamination by dustlike particulates. The stresses included that associated with sand stored at different temperatures (10 and 22 degrees C) and levels of humidity (40% relative humidity [RH], 88% RH, or complete desiccation). Irradiated RTE meats, including frankfurters, bologna, chopped ham, and deli-style roast beef, were inoculated with the L. monocytogenes-contaminated sand every 2 to 3 days over a period of 1 1/2 months. After inoculation, the RTE meats were vacuum packed and stored at 4 degrees C for 24 h. Populations of L. monocytogenes were enumerated by surface plating on nonselective and selective media to recover cells on the basis of the different stresses presented (osmotic or antibiotic). L. monocytogenes was demonstrated to be capable of surviving on the sand vector for > 151 days at 10 degrees C and 88% RH, 136 days at 10 degrees C and 0% RH, 73 days at 22 degrees C and 40% RH, and 82 days at 22 degrees C and 0% RH. These results show that under the most conservative scenario, the 73-day-old L. monocytogenes-contaminated sand was able to attach to and be recovered from the RTE meats. This study illustrated that dust contaminated with L. monocytogenes, once in contact with meat surfaces, can survive and grow, posing a health hazard to consumers.