Distance Amplitude Correction Factors for Immersion Ultrasonic Measurements through Curved Surfaces

Near net-shaped forgings offer significant advantages for component manufacture, including less material waste and reduced costs for machining to final shape. However, curved entry surfaces on near net shape forgings create complications for ultrasonic inspection methods. In immersion ultrasonic testing, entry surface curvature causes ultrasonic beam focusing or defocusing, which affects the detection sensitivity to interior material flaws, such as voids and inclusions, as compared to inspection through planar surfaces

Eddy Current Characterization of Flaws in NiCoCrAlY-Coated Nickel-Base Superalloys

Increases in performance of power generating combustion turbine engines have driven up operating temperatures and placed greater demands on turbine components. To meet these increased demands, some components such as fan blades, are fabricated from Inconel and Udimet superalloys and are coated with 0.10 to 0.15 mm of NiCoCrAlY. This coating affords the blades protection against oxidation and particle erosion, and provides a degree of thermal insulation to lower blade operating temperatures

Eddy Current Characterization of Flaws in NiCoCrAlY-Coated Nickel-Base Superalloys

Increases in performance of power generating combustion turbine engines have driven up operating temperatures and placed greater demands on turbine components. To meet these increased demands, some components such as fan blades, are fabricated from Inconel and Udimet superalloys and are coated with 0.10 to 0.15 mm of NiCoCrAlY. This coating affords the blades protection against oxidation and particle erosion, and provides a degree of thermal insulation to lower blade operating temperatures.</p

Development of Ultrasonic Inspection for a Bonded Superalloy Blade

Directionally solidified multigrain and single crystal airfoils have been used in aircraft gas turbines for over ten years and are currently found in aircraft engine-derivative gas turbines used for land-based power generation. However, the adoption of this technology for large land-based gas turbines is just underway and is not a simple scale-up. One approach to produce the large blades required for this application involves casting the blade in two separate halves and then bonding these halves together using the transient liquid phase bonding (TLPB) process [1]. This process results in a number of internal bond surfaces at the ribs. The condition of these bond surfaces must be determined prior to the blade entering service.</p

Distance Amplitude Correction Factors for Immersion Ultrasonic Measurements through Curved Surfaces

Near net-shaped forgings offer significant advantages for component manufacture, including less material waste and reduced costs for machining to final shape. However, curved entry surfaces on near net shape forgings create complications for ultrasonic inspection methods. In immersion ultrasonic testing, entry surface curvature causes ultrasonic beam focusing or defocusing, which affects the detection sensitivity to interior material flaws, such as voids and inclusions, as compared to inspection through planar surfaces.</p

Ultrasonic Evaluation of Transient Liquid Phase Bonding in Single Crystal Superalloy Castings

Transient liquid phase bonding (TLPB) is an effective means for joining high performance metal components. It differs from welding and conventional brazing in that it produces very little chemical segregation or microstructural demarcation at the bond-line. The method of transient liquid phase bonding was originally developed in the 1970’s [1] and has been used in the joining of titanium and nickel based superalloy components. In this method, a bonding alloy containing a melting point suppressing element is sandwiched between the parent metals to be joined. The temperature is raised to a point where the bonding alloy melts but the parent metals remain solid. The melting point suppressing element then diffuses away from the bondline, thus raising the melting point and solidifying the bond. Since the temperature never exceeds the melting point of the parent metal, single crystals may be joined without destroying their crystalline structure.</p

Visual and phonological pathways to the lexicon: Evidence from Chinese readers

In this study, we investigated the role of visual and phonological information in lexical access of Chinese characters. Homophonic English words have been the main source of stimuli for word recognition research. However, since these stimuli also often look alike, visual and phonological information may be confounded in reported experiment. In contrast, many homophonic Chinese characters are visually distinct. In addition, visually similar characters often have very different pronunciations. These characteristics allow a more controlled investigation of the roles of visual and phonological information in activation of meaning. In the present study, two types of Chinese characters were used in a semantic categorization paradigm: integrated characters, which contain strokes that are not separable; and compound characters, which contain at least two clearly identifiable components. The results show that the recognition of a Chinese integrated character depends primarily on visual information, whereas the recognition of a Chinese compound character relies on visual, phonological, and semantic information. It is concluded that visual information plays a greater role in Chinese character recognition than has previously been documented.link_to_subscribed_fulltex

Viraemia and Ebola virus secretion in survivors of Ebola virus disease in Sierra Leone: a cross-sectional cohort study.

BACKGROUND In survivors of Ebola virus disease, clinical sequelae including uveitis, arthralgia, and fatigue are common and necessitate systematic follow-up. However, the infection risk to health-care providers is poorly defined. Here we report Ebola virus RT-PCR data for body site and fluid samples from a large cohort of Ebola virus survivors at clinic follow-up. METHODS In this cross-sectional cohort study, consecutive survivors of Ebola virus disease attending Kerry Town survivor clinic (Freetown, Sierra Leone), who had been discharged from the Kerry Town Ebola treatment unit, were invited to participate. We collected and tested axillary, blood, conjunctival, forehead, mouth, rectal, semen, urine, and vaginal specimens for presence of Ebola virus using RT-PCR. We regarded samples to be positive for Ebola virus disease if the cycle threshold was 40 or lower. We collected demographic data from survivors of their age, sex, time since discharge from the treatment unit, and length of acute admission in the Ebola treatment unit using anonymised standard forms. FINDINGS Between April 2, and June 16, 2015, of 151 survivors of Ebola virus disease invited to participate, 112 (74%) provided consent. The median age of participants was 21·5 years (IQR 14-31·5) with 34 (30%) participants younger than 16 years. 50 (45%) of 112 participants were male. We tested a total of 555 specimens: 103 from the axilla, 93 from blood, 92 from conjunctiva, 54 from forehead, 105 from mouth, 17 from the rectum, one from semen, 69 from urine, and 21 from the vagina. The median time from Ebola treatment unit discharge to specimen collection was 142 days (IQR 127-159). 15 participants had a total of 74 swabs taken less than 100 days from discharge. The semen sample from one participant tested positive for Ebola virus at 114 days after discharge from the treatment unit; specimens taken from the axilla, blood, conjunctiva, forehead, mouth, rectum, and urine of the same participant tested negative. All specimens from the other 111 participants tested negative. INTERPRETATION Patients recovering from Ebola virus disease who do not meet the case definition for acute disease pose a low infection risk to health-care providers 6 weeks after clearance of viraemia. Personal protective equipment after this time might be limited to standard barrier precautions, unless contact with fluids from sanctuary sites is envisaged. FUNDING Save the Children International, Public Health England