Continuous Fabrication of Silicon Carbide Fiber Tows by Chemical Vapor Deposition

The feasibility of preparing small-diameter, high-strength, thermally stable silicon carbide fiber tows by the continuous chemical vapor deposition (CVD) of SiC onto carbon fiber tows was experimentally evaluated. Calculations of bending stresses and stresses caused by thermal expansion mismatch between the substrate and coating were used to evaluate the influence of coating thickness and substrate fiber diameter and type. Statistically designed and analyzed processing studies quantitatively showed the influence of key CVD process variables (temperature, pressure, and flow rates of CH₃SiCl₃ and H₂) on fiber attributes such as coating thickness and uniformity, surface roughness, percent agglomeration, and strength. Emphasis was given to conceiving and evaluating various fiber spreading devices in order to enhance coating uniformity and to minimize filament agglomeration within a tow. Uniform coatings and fiber tensile strengths as high as 4 GPa were achieved.     

Introducing electric power into a multidisciplinary curriculum for network industries

A qualitatively different graduate level curriculum for teaching electric power systems is needed. The motivation for such a new curriculum is outlined, and a specific program, now being implemented at Carnegie Mellon University, is described. The new curriculum: 1) provides students with a multidisciplinary introduction to the changing problems of the industry; 2) stresses the need for teaching systematic approaches to formulating power system problems; and 3) integrates teaching of the fundamentals for power systems with the fundamentals for other network industries. The program, referred to as the MS in Electric Power Systems (MSEPS) Program, is being developed as a special power-focused track within Carnegie Mellon's existing multidisciplinary Information Networking Institute (INI).     

Water quality management of a stretch of river Yamuna: An interactive fuzzy multi-objective approach

This paper presents an Interactive Fuzzy Multi-Objective Linear Programming (IFMOLP) model for water quality management in a river basin. The IFMOLP model formulated will first evaluate dissolved oxygen (DO) concentrations or DO deficits at a point in different reaches depending on the overall Biochemical Oxygen Demand (BOD) concentration present in the respective drain. Subsequently, the model incorporates the aspirations and conflicting objectives of the decision maker (DM) by taking into consideration the aspects relevant for pollution control boards as well as dischargers responsible for generating wastewater. The uncertainty associated with specifying the water quality criteria (based on DO concentration or DO deficit) and treatment cost to remove pollution level is incorporated by interacting the decision maker. In this process DM is asked to specify the reference aspiration levels of achievement for the values of all membership functions generated with respect to each objective. This provides flexibility for the pollution control authorities and dischargers to specify their aspirations. IFMOLP model developed herein is then used in a case study for the evaluation of optimal BOD removal in different drains located across the river Yamuna at New Delhi, India. The presented model will simulate the allocation of waste load efficiencies with satisfactory results which will indicate usefulness of the model in managing more complex river basins along with better flexible policies of water management.     

Electronic textiles: A platform for pervasive computing

The invention of the Jacquard weaving machine led to the concept of a stored "program" and "mechanized" binary information processing. This development served as the inspiration for C. Babbage's analytical engine-the precursor to the modern-day computer. Today, more than 200 years later, the link between textiles and computing is more realistic than ever. In this paper, we look at the synergistic relationship between textiles and computing and identify the need for their "integration" using tools provided by an emerging new field of research that combines the strengths and capabilities of electronics and textiles into one: electronic textiles, or e-textiles. E-textiles, also called smart fabrics, have not only "wearable" capabilities like any other garment, but also have local monitoring and computation, as well as wireless communication capabilities. Sensors and simple computational elements are embedded in e-textiles, as well as built into yarns, with the goal of gathering sensitive information, monitoring vital statistics, and sending them remotely (possibly over a wireless channel) for further processing. The paper provides an overview of existing efforts and associated challenges in this area, while describing possible venues and opportunities for future research.     

Investigation of reliability issues in high power laser diode bar packages

As applications continue to demand increasingly higher optical output power and longer lifetime, thermo-mechanical stresses on dissimilar materials interfaced for packaging pose an ever-growing challenge for the realization of a durable system. Particularly important for an epitaxy-down configuration is the die-attachment interface, which is desired to be defect free and stress managed for reliable optical alignment. A knowledge of the changes in the physical defect density and magnitude of the thermo-mechanical stress present in the active region as a function of the fabrication process and aging is crucial to an understanding of the influence of the process parameters and operating conditions on device performance and reliability. In this study, we investigated high power laser diode array packages aged under various conditions. Microscopic defect analyses of the die attachment interface and device stress were carried out using primarily metallography, scanning electron microscopy, scanning acoustic microscopy, microhardness, and micro-Raman spectroscopy. It was noted that the intermetallic compounds and microscopic physical defects at the die attach interface are detrimental to transient heat transfer, and thus, overall package reliability. Using micro-Raman spectroscopy, we found that tensile stress near the bar-package interface increases with aging for the first few hundred hours and then decreases with further aging.     

A note on error bounds for approximation in inner product spaces

In a recent paper a method is described for constructing certain approximations to a general element in the closure of the convex hull of a subset of an inner product space. This is of interest in connection with neural networks. Here we give an algorithm that generates simpler approximants with somewhat less computational cost.     

A functional chimeric modular polyketide synthase generated via domain replacement

We report here a case in which for hemoptysis during menstruation (catamenial hemoptysis) right middle lobectomy was performed thoracoscopically under a preoperative diagnosis of pulmonary endometriosis with a successful outcome. The patient was a 27-year-old housewife who from the age of 24 years experienced hemoptysis during menstruation, and was diagnosed as having pulmonary endometriosis on the basis of detailed examinations including bronchoscopy and chest CT. From the age of 26 years hormone therapy was administered, but the hemoptysis recurred with the menstruation following its cessation. After admission to this department bronchoscopy performed at the time of menstruation revealed bleeding from right B4 while chest CT showed an abnormal shadow in right S4 b. Right middle lobectomy was then performed thoracoscopically under a diagnosis of right middle lobe endometriosis. In the resected specimen findings of pulmonary hemosiderosis, granulomatous phlebitis and micrometastases from a thyroid cancer were noted. The postoperative course was favorable with no further episodes of hemoptysis occurring. In this case histological proof of endometriosis could not be obtained, but the diagnosis of pulmonary endometriosis was strongly suggested by the clinical course and objective findings such as pulmonary hemosiderosis.     

IQ, race, and adoption.

Argues that the genetic and social variables were so confounded in S. Scarr and R. A. Weinberg's (see record 1977-07996-001) article on Black children adopted by White families that the results are consistent with virtually any theory of race differences in IQ. It is difficult to see any scientific or applied value in transracial adoption studies. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Fixed-width confidence interval estimation of the inverse coefficient of variation in a normal population

A sequential procedure is developed in order to construct a confidence interval of “fixed-width and preassigned coverage probability” for the inverse of the coefficient of variation of a normal population. The proposed sequential procedure is proved to be “asymptotically efficient and consistent” in the sense of Chow and Robbins ([1]: Ann. Math. Statist. 36, 457–462 (1965)). Asymptotic distribution of the stopping time is derived.     

Robotic visual servoing and robotic assembly tasks

Visual feedback has traditionally been used in the assembly process to a very limited extent. By incorporating high bandwidth visual feedback into the manipulator feedback loop, more flexible and adaptable robotic assembly systems can be developed. The authors present experimentally tested algorithms and propose solutions for the problem of dynamic sensor placement in assembly tasks