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61.
In this paper, we propose a shrinkage testimator for the shape parameter λ of an Inverse Gaussian distribution when the estimated value of λ is available in such a way that either λ = λ1 or λ = λ2(>;λ1) is expected. The (α + β)min test for testing the hypothesis H0: λ = λ1 against H1: λ = λ2 is derived. The shrinkage factors are chosen to be the function of the (α + β)min test. The shrinkage testimator is found to be more efficient (in the sense of the MSE) than the UMVUE in certain parametric space. 相似文献
62.
Radovan Ćirić Svetislav Čantrak Karlo T. Raić Rebeka Rudolf Ivan Anžel 《Metals and Materials International》2009,15(5):831-841
The paper presents the viscoplastic phenomena observed during the rotational friction-welding process of high-speed steel
M2 (AISI SAE) with carbon steel 1060 (AISI SAE). The structure, phase composition and distribution of the carbide phase in
the friction plane and adjoining zones are examined by using optical microscopy (OM) with a system for quantitative analysis,
and scanning electron microscopy (SEM) in addition to EDS analysis. The experimentally-checked mathematical relationship is
suggested for the calculation of the radial movements of the carbide phase, immediately next to the friction plane. On the
basis of qualitative and quantitative evaluation of the microstructural and rheological appearances, a model of carbide phase
distribution is also established in the viscoplastic and viscous layers in the area of the friction plane. 相似文献
63.
Cross-sectional transmission electron microscopy is used to determine the structure of Au-, Ge- and Ni-based ohmic contacts at the interface with AlGaAs/GaAs modulation-doped field-effect-transistor material. Significant lateral diffusion (?0.12?m) is found to occur at the edge of the contact during alloying. The observed contact structure places a limit on minimum geometries and must be taken into account if accurate device modelling is to be carried out. 相似文献
64.
Kumud Ranjan Jha Manish Rai 《AEUE-International Journal of Electronics and Communications》2010,64(2):177-185
This paper presents a new slow wave open-loop resonator filters with reduced size and improved stopband characteristics. A comprehensive treatment of different kind of coupling in this structure is demonstrated. Two and four resonator band pass filters at center frequency 2.15 and 2.30 GHz with different bandwidth are designed. The simulated results are verified with the help of two different software packages (IE3D and Sonnet Lite). 相似文献
65.
Three samples of vinyl ester resins (VERs) were synthesized using bisphenol‐A‐based epoxy resins of varying epoxide equivalent weights (EEW) and acrylic acid in presence of triphenylphosphine as a catalyst at 80 ± 2°C. The cresyl glycidyl ether was used as reactive diluent during the synthesis of VERs. A suitable reaction mechanism was proposed and discussed for the reactions involving epoxide group and acid groups. This was further confirmed by infrared spectroscopic analysis. The maximum peak temperature from DSC were at 106.05°C, 114.20°C, and 128.86°C for benzoyl peroxide initiated VERs viz. samples V1CV, V2CV, and V3CV, respectively, increased with the increase of EEW of the parent epoxy resin. It has also been found that the films of VER having highest EEW of bisphenol‐A epoxy resin showed best chemical resistance amongst all other VERs in this study. The mechanical properties such as hardness and flexibility also showed a similar trend. The thermal stability was found to decrease with the increase of EEW of bisphenol‐A epoxy resin in the VERs. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 相似文献
66.
67.
P. K. Rai Vaibhav Pandey K. Chattopadhyay L. K. Singhal V. Singh 《Journal of Materials Engineering and Performance》2014,23(11):4055-4064
The effect of ultrasonic shot peening (USSP) was studied on microstructural modification and mechanical properties such as microhardness, yield strength, tensile strength, and low cycle fatigue (LCF) life of a nitrogen stabilized austenitic stainless steel, at room temperature. There was grain refinement up to nano scale in surface region of the shot peened specimens and the microhardness was increased markedly up to the depth of approximately 100 µm. There was insignificant increase in yield and tensile strength, but drastic reduction in LCF life, particularly at low strain amplitude, from USSP. The nominal increase in yield and tensile strength was due to grain refinement in the surface region and drastic fall in LCF life was due to surface cracking resulting from USSP. 相似文献
68.
Renaldas Raišutis Rymantas Kažys Egidijus Žukauskas Liudas Mažeika 《NDT & E International》2011,44(7):645-654
In aerospace industry, one of the most important parts of gliders and motor-gliders is a lightweight longeron reinforcement made of carbon fibre reinforced plastics (CFRP) rods, known as Graphlite SM315 composite. During manufacturing, the rods as constructional elements are glued together in epoxy-filled matrix in order to build the arbitrary spar profile. The defects present in single rods such as breakage of fibres, multiple delaminations due to the lack of bonding between fibres and reduction in density affect essentially the strength and the fail-safety of the overall construction.The aim of the present work is to investigate the effects (transmission, reflection, scattering and mode conversion) of guided waves propagation along a square-shape CFRP rod in the case of contactless excitation/reception and interaction with region of multiple delaminations applying the numerical model and performing experiments.The square-shape CFRP composite rods possessing internal artificial delamination type defects have been investigated by numerical modelling and experiments employing the developed air-coupled technique (pitch-catch set-up) for cases of conventional transmission and advanced back-scattering configurations. Numerical predictions of guided wave interaction with a multiple delamination type defect in a CFRP composite rod have been made and the interaction mechanism explained. It is possible to conclude, that the actual sizes of the internal defects have been clearly detected using reception of the back-scattered waves over the edges of the defective regions only. 相似文献
69.
Prashant Kumar Rai Ashok Kumar Pathak Somenath Ghatak Geeta Watal Awadhesh Kumar Rai Rama Jayasundar 《Sensing and Instrumentation for Food Quality and Safety》2013,7(3):114-121
Although plants have long been a major source of medicine, there is renewed interest in studying the phytochemistry and use of herbal formulations. This paper reports spectroscopic analysis using Laser Induced Breakdown Spectroscopy (LIBS) of a polyherbal formulation, whose antidiabetic activity has also been demonstrated on rat models. LIBS analysis revealed the presence of elements such as Na, K, Mg, Ca, H, O and N. The antidiabetic study showed that amongst the four doses studied (50, 100, 150 and 200 mg/kg bw), the dose of 150 mg/kg bw registered the maximum fall in Blood Glucose Level (BGL) in both normal and diabetic (sub and mild) rats in the Glucose Tolerance Test (GTT) study—normal rats (22 %), sub-diabetic (36.6 %) and mild-diabetic (39 %). The dose of 150 mg/kg also showed the maximum fall of 23.7 % and 22 % in BGL during fasting BGL and GTT studies of normal rats, respectively. The formulation also showed significant antioxidant activity assessed using in vitro assays. The study validates for the first time the therapeutic use of an antidiabetic polyherbal formulation. 相似文献
70.
Alok Kumar Rai N. K. Singh Sang-Kwon Lee K. D. Mandal D. Kumar Om Parkash 《Journal of Materials Science: Materials in Electronics》2011,22(9):1286-1289
Dielectric properties of iron doped CaCu3Ti4O12 (CCTO), viz. CaCu3Ti3.9Fe0.1O12 (CCTFO) prepared by a novel semi-wet route have been investigated. X-ray diffraction of powder sintered at 900 °C show formation
of single phase solid solution. Energy dispersive X-ray spectroscopy (EDX) confirmed the presence of CuO rich phase at grain
boundaries of CCTFO. Nature of dielectric relaxation observed above room temperature is studied using complex plane impedance
analysis and modulus spectroscopy. It has been found that out of the two relaxations reported earlier above room temperature,
one occurring at lower temperature is due to grainboundaries interfacial polarization. 相似文献