Polarization Characteristics of Double-Clad Elliptical Fibers

A scalar variational analysis based on a Gaussian approximation of the fundamental mode of a double-clad elliptical fiber with a depressed inner cladding is studied. The polarization properties and graphic results are presented; they are given in terms of three parameters: the ratio of the major axis to the minor axis of the core, the ratio of the inner cladding major axis to the core major axis, and the difference between the core index and the inner cladding index. The variations of both the spot size and the field intensity with core ellipticity are examined. It is shown that high birefringence and dispersion-free orthogonal polarization modes can be obtained within the single-mode region and that the field intensity distribution may be more confined to the fiber center than in a single-clad elliptical fiber

Temperature and Strain Sensitivity Measurements of High-Birefringent Polarization-Maintaining Fibers

The strain and temperature sensitivities of three common commercial high-birefringent polarization maintaining fibers (bow-tie, polarization-maintaining and absorption-reducing, and elliptical core fibers) have been measured by using a dynamic polarimetric method. The experimental setup and measuring process are described in detail. Where possible, the measuring data are compared with published data, and good agreement is obtained

Temperature and Strain Sensitivities of High-Birefringence Elliptical Fibers

We have analyzed and calculated the temperature and strain sensitivities of a high-birefringence double-clad elliptical fiber. We propose a method to minimize these sensitivities without increasing the fiber size or weight; this is achieved by selecting suitable fiber parameters—core ellipticity, refractive index difference, and thickness of the inner cladding. In addition, we discuss the design of temperature- or strain-insensitive fibers which may be used in polarimetric strain or temperature sensors. This method may also be used to minimize or enhance other external effects

Minimization of Temperature Effects of High-Birefringent Elliptical Fibers for Polarmetric Optical-Fiber Sensors

The temperature dependence of polarization-maintaining fibers is a problem in polarimetric optical-fiber sensors. We report a novel method for making a temperature-insensitive, polarization-maintaining fiber, which may be used for the sensing part in a polarimetric strain sensor. The fiber has a double-clad elliptical core with built-in stresses in the core and cladding regions. To minimize the temperature sensitivity, the built-in stresses are balanced with the refractive-index differences and the core ellipticity properly chosen. The temperature and strain sensitivities of the fiber are calculated. A practical design and some potential applications of such a temperature-insensitive fiber with a high strain sensitivity are presented

A Hybrid Intelligent System for Stamping Process Planning in Progressive Die Design

This paper presents an intelligent, hybrid system for stamping process planning in progressive die design. The system combines the flexibility of blackboard architecture with case-based reasoning. The hybrid system has the advantage that it can use past knowledge and experience for case-based reasoning when it exists, and other reasoning approaches when it doesn’t exist. A prototype system has been implemented in CLIPS and interfaced with Solid Edge CAD system. An example is included to demonstrate the approach.Singapore-MIT Alliance (SMA

Functional Modeling in Conceptual Die Design

The use of function has been recognized as an important part of the design process over last two decades, especially at the conceptual design stage, due to its critical role in determining the final product’s functionality. Although there are now some general methodologies dealing with functions or reasoning about functions, virtually no commercial CAD system can support conceptual design process due to their focus on geometrical modeling but not functional modeling. This paper presents a functional modeling approach to guide conceptual die design through functional reasoning steps including functional decomposition, functional supportive synthesis and function-structure mapping. The formed functional model provides a good basis to generate various die structures at the conceptual design stage, because function is a higher level of abstraction than structure, and helps to capture the designer’s intent. The functional modeling process has been implemented in a computerized design environment to expedite the conceptual die design process.Singapore-MIT Alliance (SMA

Magnetization reversal and magnetic anisotropy in Co network nanostructures

The magnetization reversal and magnetic anisotropy in Co network structures have been studied using magneto-optic Kerr effect (MOKE). An enhancement of the coercivity is observed in the network structures and is attributed to the pinning of domain walls by the hole edges in the vicinity of which the demagnetizing field spatially varies. We find that the magnetization reversal process is dominated by the intrinsic unaxial anisotropy (2K(u)/M(s)approximate to 200 Oe) in spite of the shape anisotropy induced by the hole edges. The influence of the cross-junction on the competition between the intrinsic uniaxial anisotropy and the induced shape anisotropy is discussed using micromagnetic simulations

Functional design of mechanical products based on behavior-driven function-environment-structure modeling framework

The relative significance of upstream design activity to downstream design activity is widely recognized, due to its critical role in determining the final product’s functionality. Although there are now some general methodologies dealing with functions or reasoning about functions, virtually no commercial CAD system can support functional design. In functional modeling, a design problem is represented in a hierarchy of functions and the behaviors that realize the functions. This paper presents a functional design methodology based on a behavior-driven function-environment-structure (B-FES) modeling framework to guide functional design through functional reasoning steps including causal behavioral reasoning (CBR) and functional decomposition. The proposed functional design starts from a set of design specifications including functional requirements and design constraints, and results in diverse behavioral schema corresponding to a set of design alternatives. A design example for functional design of a terminal cut-off unit in an automatic assembly system is used to provide a demonstration of the proposed functional design methodology.Singapore-MIT Alliance (SMA

The Pobei Cu-Ni and Fe ore deposits in NW China are comagmatic evolution products: evidence from ore microscopy, zircon U-Pb chronology and geochemistry

The Pobei mafic-ultramafic complex in northwestern China comprises magmatic Cu-Ni sulfide ore deposits coexisting with Fe-Ti oxide deposits. The Poshi, Poyi, and Podong ultramafic intrusions host the Cu-Ni ore. The ultramafic intrusions experienced four stages during its formation. The intrusion sequence was as follows: dunite, hornblende-peridotite, wehrlite and pyroxenite. The wall rock of the ultramafic intrusions is the gabbro intrusion in the southwestern of the Pobei complex. The Xiaochangshan magmatic deposit outcrops in the magnetitemineralized gabbro in the northeastern part of the Pobei complex. The main emplacement events related to the mineralization in the Pobei complex, are the magnetite-mineralized gabbro related to the Xiaochangshan Fe deposit, the gabbro intrusion associated to the Poyi, Poshi and Podong Cu-Ni deposits, and the ultramafic intrusions that host Cu-Ni deposits (Poyi and Poshi). The U-Pb age of the magnetite-mineralized gabbro is 276±1.7Ma, which is similar to that of the Pobei mafic intrusions. The εHf(t) value of zircon in the magnetite-mineralized gabbro is almost the same as that of the gabbro around the Poyi and Poshi Cu-Ni deposits, indicating that the rocks related to Cu-Ni and magnetite deposits probably originated from the same parental magma. There is a trend of crystallization differentiation evolution in the Harker diagram from the dunite in the Cu-Ni deposit to the magnetite-mineralized gabbro. The monosulfide solid solution fractional crystallization was weak in Pobei; thus, the Pd/Ir values were only influenced by the crystallization of silicate minerals. The more complete the magma evolution is, the greater is the Pd/Ir ratio. The Pd/Ir values of dunite, the lithofacies containing sulfide (including hornblende peridotite, wehrlite, and pyroxenite) in the Poyi Cu-Ni deposit, magnetite-mineralized gabbro, and massive magnetite, are 8.55, 12.18, 12.26, and 18.14, respectively. Thus, the massive magnetite was probably the latest product in the evolution of the Pobei mafic-ultramafic intrusions. We infer that the Cu-Ni sulfide and Fe-Ti oxide ores in the Pobei area were products of a cogenetic magma at different evolutionary stages; at the late stage, the magma became iron enriched through crystallization differentiation. The magma differentiation occurred in a deep staging magma chamber emplaced in the upper magma chamber. Earlier crystallized olivine with some interstitial sulfides gathered at the bottom of the staging magma chamber because of its greater density. That is to say, the ultramafic magma hosting the Cu-Ni sulfide formed at the bottom of the staging magma chamber, while the magnetite-mineralized gabbro was in the upper part. However, the magnetite-mineralized gabbro injected into the upper magma chamber first and the ultramafic lithofacies containing the olivine and the interstitial Cu-Ni sulfides were subsequently emplaced in the upper magma chamber as crystal mush

Production Optimization,Molecular Characterization and Biological Activities of Exopolysaccharides from Xylaria nigripes

The optimal culture conditions of exopolysaccharides (EPS) production in submerged culture medium by Xylaria nigripes were determined using orthogonal matrix method. The optimal medium (per liter) EPS was 60.0 g L–1 maltose, 1.0 g L–1 peptone, 5 mmol L–1 KH2PO4, and initial pH 7.0 at 28 oC. In the optimal culture medium, the maximum EPS production was 11.967 g L–1 in shake flask. Two groups of EPSs (designated as Fr-I and Fr-II) were obtained from the culture filtrates by size exclusion chromatography (SEC), and their molecular characteristics were examined by a multiangle laser-light scattering (MALLS) and refractive index (RI) detector system. The weight-average molar masses of Fr-I and Fr-II of EPS were determined to be 6.327104 and 1.478104 g mol–1, respectively. The SEC/MALLS analysis revealed that the molecular formation of Fr-I is of nearly globular shape. Furthermore, the experiments in vitro indicated that X. nigripes EPS exhibited high antioxidative effects though its antitumour activity was limited