Ultrasonic wave velocities were determined at parallel and perpendicular to manufacturing direction and at the interval angles
of 15° in clockwise and counterclockwise directions of particleboard and fiberboard. The experimental results were compared
with the predicted values using some empirical formulae such as Hankinson and Jacoby equations. The results showed that the
ultrasonic wave velocity were the highest in parallel direction in particleboard and fiberboard and decreases with increase
of angle and the lowest values occurred in perpendicular direction. The predicted ultrasonic velocity using Hankinson and
Jacoby equations are in close agreement with the measured values. Relationship between ultrasonic wave velocities and particles
and fibers angle could be successfully presented by cubic and quadratic regression equations as well. 相似文献
In this paper, we describe Swoop, a hypermedia inspired Ontology Browser and Editor based on OWL, the recently standardized Web-oriented ontology language. After discussing the design rationale and architecture of Swoop, we focus mainly on its features, using illustrative examples to highlight its use. We demonstrate that with its Web-metaphor, adherence to OWL recommendations and key unique features, such as Collaborative Annotation using Annotea, Swoop acts as a useful and efficient Web Ontology development tool. We conclude with a list of future plans for Swoop, that should further increase its overall appeal and accessibility. 相似文献
This paper describes the development of a hermetic micropackage with high-density on-chip feedthroughs for sensor and actuator applications. The packaging technique uses low-temperature (320°C) electrostatic bonding of a custom-made glass capsule (Corning 7740, 2×2×8 mm3) to fine grain polysilicon in order to form a hermetically sealed cavity. High-density on-chip multiple polysilicon feedthroughs (200 per millimeter) are used for connecting external sensors and actuators to the electronic circuitry inside the package. A high degree of planarity over feedthrough areas is obtained by using grid-shaped polysilicon feedthrough lines that are covered with phosphosilicate glass (PSG), which is subsequently reflown at 1100°C in steam for 2 h. Saline and DI water soak tests at elevated temperatures (85 and 95°C) were performed to determine the reliability of the package. Preliminary results have shown a mean time to failure (MTTF) of 284 days and 118 days at 85 and 95°C, respectively, in DI water. An Arrhenius diffusion model for moisture penetration yields an expected lifetime of 116 years at body temperature (37°C) for these packages. In vivo tests in guinea pigs and rats for periods ranging from one to two months have shown no sign of infection, inflammation, or tissue abnormality around the implanted package 相似文献
3D printing offers great potential for developing complex flexure mechanisms. Recently, thickness-correction factors (TCFs) were introduced to correct the thickness and stiffness deviations of powder-based metal 3D printed flexure hinges during design and analysis. However, the reasons for the different TCFs obtained in each study are not clear, resulting in a limited value of these TCFs for future design and fabrication. Herein, the influence of the porous layer of 3D printed flexure hinges on the hinge thickness is investigated. Samples of parallelogram flexure mechanisms (PFMs) were 3D printed using selective laser melting (SLM) and 316L stainless steel powder. A 3D manufacturing error analysis was completed for each PFM sample via 3D scanning, surface roughness measurement and morphological observation. The thickness of the porous layer of the flexure hinge was independent of the designed hinge thickness and remained close to the average powder particle diameter. The effective hinge thickness could be estimated by subtracting twice the value of the porous layer thickness from the designed value. Guidelines based on finite element analysis and stiffness experiments are proposed. The limitations of the presented method for evaluating the effective hinge thickness of flexure hinges 3D printed via SLM are also discussed.
This article presents experimental and numerical study of an under-ground water reservoir (cistern) during six months operation in a semi-arid region. The cistern with one dome, four windcatchers and a water reservoir is located in Lar, a hot arid city at south of Iran. Outdoor and indoor air temperature and humidity, water temperature in three depths and dome surface temperature were measured using a data logging system. The results show that the average air humidity inside the cistern was almost constant during the experiments but its slight variation during a day follows inside air temperature changes. The inside air temperature was always lower than the ambient temperature and inside and outside average air temperature difference was about 6 °C. The difference was slightly higher in the hot seasons. The water reservoir was also modeled in 2D, axisymmetric and quasi steady numerical simulation for six months of operation. Highly stratified water temperature distribution was observed in the numerical results as well as the experimental measurements. 相似文献
In this survey article, we first introduce the concept of quasi-coincidence of a fuzzy interval value with an interval valued fuzzy set. This concept is a generalized concept of quasi-coincidence of a fuzzy point within a fuzzy set. By using this new idea, we consider the interval valued (∈,∈∨q)-fuzzy sub-hypernear-rings (hyperideals) of a hypernear-ring, and hence, a generalization of a fuzzy sub-near-ring (ideal) is given. Some related properties of fuzzy hypernear-rings are described. Finally, we consider the concept of implication-based interval valued fuzzy sub-hypernear-rings (hyperideals) in a hypernear-ring, in particular, the implication operators in Lukasiewicz system of continuous-valued logic are discussed. 相似文献