bluuebunny/crossref_metadata_2025_split huggingface dataset:
Laser-Induced Failure in Biased Silicon Avalanche Photodiodes
Authors: Watkins SE , Zhang C-Z , Walser RM , Becker MF 
Published: March 2009

The characteristics of laser-induced electrical failure in biased silicon avalanche photodiodes have been observed. The samples were RCA reach-through avalanche photodiodes with antireflection coatings. They were biased at typical operating voltages during irradiation. The laser source was a Q-switched 1064 nm Nd:YAG pulsed laser operating at 10 Hz with a 10 ns pulse length and with a 300 μm spot radius.
The current-voltage characteristics were monitored for permanent change as a function of laser fluence and the degradation thresholds were found. Two types of change were observed. The first type was a large increase in bulk leakage current. It may be modeled by the introduction of defects into the depletion region by deep melting transients. The second type was catastrophic failure in which the devices were electrically shorted after irradiation. It may be modeled by excessive current density in the photodiode junction. The type of failure was determined by the parameters of the biasing circuit.
An Error Analysis of the Wyko TOPO Noncontact Surface Profiler
Authors: Hodgkin VA 
Published: March 2009

An increasingly important tool in the characterization and measurement of optical materials and components in the Wyko TOPO Noncontact Surface Profiler. Optically, it consists of a low- to medium-power microscope in which the objective, depending upon the power, is a visible light interferometer of either Michelson, Mireau, or Linnik design. By integrating a detector array into the viewing system and attaching the reference arm of the interferometer to a piezoelectric transducer, the technique of surface profiling by phase shifting is accomplished by computer.
The potential utility of this system to the investigator interested in the fundamental mechanisms of laser-induced damage is enormous, provided that the user is aware of its proper use and limitations. This paper is intended to act as a user's guide to the TOPO system in such cases and to document its precision and accuracy limitations given a variety of surface types and measurement configurations.
Scattering Characterization of Materials in Thin Film Form
Authors: Amra C 
Published: March 2009

The “scattering characterization” that was developed in Marseilles enables us today, with the help of complementary tools (causal model, isotropy degree, …), to point out the origin of micro-roughness in optical coatings without any ambiguity. Each material can be associated to a key parameter that characterizes its scattering. These parameters can be determined through measurements performed on one single layer, and then can be used to predict scattering in more complex systems.Experimental results (IAD, IP) are presented and show that in most cases, scattering measurement of substrate is sufficient to predict scattering from any coating with a high accuracy. However, at very low scattering levels (under 10-6), this prediction is limited by the presence of local defects in the coatings.
The Evolution of Molecular Beam Deposition (MBD) from Laboratory to Production Usage
Authors: Hale CCH , Muirhead IT , Fisher SP , Mathew GJH 
Published: March 2009

The use of molecular beam technology (MBD) under ultra high vacuum conditions (UHV) has proved to be a highly controllable process capable of producing dense films which are free of porosity, low in impurities and having bulk like optical properties. These distinctions are requisite for coatings which require a high laser damage threshold, low scatter and stable spectral characteristics. The application also lends itself to the formation of novel distributed Bragg reflectors (DBR) and rugate structures which require a highly controllable deposition process to form the many, often very thin, layers involved.
In order to further the research in this field and produce advanced optical coatings for applications requiring stringent specification beyond the capability of conventional technology, a VG Semicon V90H MBE system has been installed at OCLI, Scotland, purchased and operated under a joint venture between OCLI Ltd and Heriot Watt University. This facility can provide a thickness uniformity of better than +/- 0.5% over a 4" substrate.
This paper will review the current results from this unique deposition facility and describe the advances made in depositing complex multilayer coatings.
Investigation and Modelling of Laser Damage Properties of Fabry-Perot Filters
Authors: McInnes A , MacDonald CM , Gibson DR , Wilson AD 
Published: March 2009

The electric field distribution within a fabry-perot etalon is readily variable by changing the angle of incidence or the thickness of the etalon. The laser damage threshold (LDT) of Fabry-Perot etalons was measured as a function of electric field distribution, monitored through the transmittance. Two types of etalon were used — thin film Fabry-Perot devices with high finesse were investigated at 1.064μm, and a simple dielectric slab etalon (Germanium) was investigated at 10.6μm.
In the latter case the results show a correlation between the LDT and the inverse square of the calculated peak electric field (1/E2) in the sample. For the thin film Fabry-Perot, the correlation is between the LDT and 1/E2 at the spacer boundaries. Subsequent sample analysis also suggests that damage was initiated at spacer boundaries.
It is concluded that the laser damage properties of such etalons are in agreement with theoretical expectations, and that their damage behaviour can be described by a single parameter.
High Damage Threshold AlO.OH-SiO2 HR Coatings Prepared by the Sol-Gel Process
Authors: Thomas IM 
Published: March 2009

Our study of highly reflective (HR) dielectric coatings prepared by the sol-gel process has indicated that hydrated alumina and silica are the materials of choice for the high and low index components respectively.
We can now prepare 32–36 quarter-wave-layer samples from colloidal suspensions of the relevant oxides by spin coating at room temperature. These have reflectivities of about 99% and damage thresholds in the range 30–40 J/cm2 at 1064 nm with 16 ns pulses at 30 Hz. This threefold improvement in threshold over that reported earlier for this system was attributed to an improvement in the preparative technique particularly in regard to cleanliness. Coatings have been prepared recently on substrates up to 8” in diameter and scale-up development continues.
The Response of Multilayer Dielectric Coatings to Low Fluence Ultraviolet Light Exposure
Authors: Sanders VE , Early JW , Leamon W 
Published: March 2009

Multilayer dielectric high-reflectance coatings were investigated for potential application in a high-average-power, 1-μm wavelength, free-electron laser oscillator. Of concern are the ultraviolet harmonics of the primary wavelength generated within the oscillator that tend to degrade the dielectric coatings. These coatings are required to be high reflecting and low absorbing with respect to the 1-μm wavelength and resist degradation/damage from the ultraviolet harmonics.
A KrF excimer laser was used to generate the low fluence ultraviolet light at 248-nm wavelength, a wavelength that simulates the fourth harmonic of the 1-μm free-electron laser. A variety of candidate dielectric oxide thin film materials are compared in this report. In each multilayer dielectric high reflector measured, a candidate high-index dielectric material is used in combination with SiO2 as the low-index material. Damage test measurements are reported for the 248-nm wavelength with HfO2 being the high-index material with significantly the best results.
Performance Study of Single Ply Roof Membranes in the Northeast United States
Authors: Peterson RH 
Published: March 2009

Single Ply roof membranes have been in extensive use inthe Northeast Region of the United States for a period of over twelve years. Although numerous systems and application procedures have been employed there has been limited publication of field performance data on in-situ systems. This study involves the review of both EPDM roof membranes and PVC roof membrane systems that were placed in service between 1977 and 1984. The roof systems included in the study are all reroofing systems of known construction, contractors, materials manufacturers and design. The performance study included a review of the documented history of each roof from design through construction and post construction. Warranty claims, if applicable, were reviewed as well as all other available recorded data.
Building occupants/Owners were interviewed to provide additional undocumented data. All roof systems in the study were inspected to establish existing conditions and to evaluate the level of deterioration of the various roof system components.
Accumulated data from documented history, interviews and field observations will be analyzed in this paper and defects will be summarized. Causation of defects and deterioration were also considered and classified into one or more of the catagories of design defficiency, material performance, improper workmanship and/or lack of appropriate and regular maintenance.
Conclusions relative to the performance of the systems studied will be presented and considerations given to the effect on performance by known system changes.
Porosity of Glass Fiber Felts Used in Built-Up Roofing
Authors: Cash CG 
Published: March 2009

This paper describes a test method for measuring the relative porosity of asphalt coated glass fiber felts. For this paper, porosity is defined as flow through felt.
I tested the effect of the relative porosity of the felt using a computer model to calculate the flow of coal-tar pitch through the felts in an ideal membrane, exposed to normal Boston, Mass, and Miami, Fla. temperatures.
These data show the relative porosity of the glass fiber felts is highly variable. The mass of the built-up roofing aggregate presses the glass fiber felts to the bottom of the membrane.
I recommend, based on my field observations, our laboratory tests and the calculations reported in this paper, that only steep asphalt, ASTM D 312, Types 3 or 4, be used between the plies of asphalt coated glass fiber felts in the construction of built-up roofing membranes. Coal-tar pitch and dead level asphalt should not be used with glass fiber felts until dependable test methods and standards for the relative porosity of the glass fiber felts are established.
Statistics from Built-Up Roofing Sample Analyses
Authors: Cash CG , Henshell J 
Published: March 2009

This paper presents data from over 1,000 built-up roofing membrane samples analyzed by the contributing laboratories. These data were assembled in Task Force D 8.20.15, chaired by Justin Henshell, to determine the typical values that can be expected from the quantitative analysis of built-up roofing membranes.
These data are evaluated by standard statistical methods to determine the type of distribution, mean, standard deviation, range (95% confidence) and the typical values. For this paper the typical range is defined as the range that includes more than 50% of the samples.
The range of the typical values calculated are broader than the recommendations by the roofing material manufacturers, but not as broad as the recommendations of the National Roofing Contractors Association.
Temperature and Moisture Effects on the Engineering Properties of Silicone Sealants
Authors: Tock RW 
Published: March 2009

Physical property changes for two structural silicone rubber sealants were studied to determine the effects of expected variations in environmental temperature and moisture. Test coupons were subjected to uniaxial tensile forces at different isotherms and moisture levels. The elastic modulus at zero strain, stress at a function of extension, and relaxation times were determined for the two sealants.
For extensions of zero to thirty percent, and for temperatures over a range of 0°C to 30°C, both sealants were found to behave as ideal elastomers. The use of the model for an ideal rubber allowed the cross link density, tensile modulus, and stress to be quantified for a given isotherm. Normal, environmental temperature variations did not compromise sealant performance.
Moisture (immersion in water) appeared to have little effect on the measured mechanical properties. The pH of the water over a range of 5 to 12 also appeared not to affect sealant performance. However, strong sulfuric acid solutions (pH &lt; 2.0) seriously compromised the integrity of both materials.
Adhesive Properties of Silicone Sealants
Authors: Gutowski WS 
Published: March 2009

It is shown in this paper, that the strength of adhesion between the sealant and substrate depends upon surface properties of these materials expressed in terms of specific components of their surface energies and the acid-base interactions.
The predictive model regarding the relationship between the bond strength and the energy of acid-base interaction presented in this paper may be applicable in both dry and humid/wet environments.
Silicon Modified Polyethers for Moisture Cured Sealants
Authors: Timberlake JF 
Published: March 2009

Silicon modified polyethers are an intermediate for the preparation of one-part and two-part sealants. Silicon modified polyethers consist of a polyoxypropyl-ene backbone with methyldimethoxysilane end groups. Curing with moisture in the presence of catalysts gives flexible polymers with siloxane bonds connecting the poly-ethers. The primary application for these silicon modified polyethers is in construction sealants.
Silicon modified polyethers give soft sealants which have excellent weatherability and durability (joint movement) with little changes in properties after four years under normal use conditions. Weathering data demonstrate that these sealants will last for many years in outdoor exposure. The sealants show good adhesion to most substrates including aluminum, mortar, and stone. Good curing rates are observed in both one-part and two-part sealants over a range of temperatures. The sealants are nonstaining on stone and can be easily painted.
Choice of Testing, Evaluation Methods, and Quality Criteria in Corrosion Engineering
Authors: Bartoň K , Knotková D , Holler P 
Published: March 2009

This paper proposes a general scheme for the design of test programs to assess corrosion resistance in a meaningful way. Any metallic material or coated metal product that is to be used in a specific set of conditions may suffer corrosion. The chemical and physical factors of the service application, together with the metallic material, determine the type and extent of corrosion damage encountered. Corrosion science can be used to specify the critical environmental factors in the test method.
The test program can provide results that are important for the following: the development of new materials and coatings; the choice of protective systems for new equipment designs; the development of quality control programs and quality acceptance tests. Statistical methods are essential to determine the significance levels of results and the corresponding material specifications.
Stress-Corrosion Cracking of Mn-Bronze Castings and Test Specimens in New York City Water Distribution Shafts
Authors: Andersen GA , Donnellan PB 
Published: March 2009

Stress-corrosion cracking (SCC) has been found to be the cause of failure of 48-in. (1219.2-mm) and 30-in. (762-mm) diameter manganese bronze gate valve bodies, a 48-in.-diameter shaft cap, and 1½-in. (38-mm)-diameter nuts. All of these in-service failures occurred in New York City distribution shafts for Water Tunnels Nos. 1 and 2. The valves and shaft cap, which were made of Copper Development Association (CDA) Alloy C86500, failed in predominantly transgranular mode with some intergranular cracking. The nuts, made of CDA Alloy C86300, cracked in an intergranular mode only.
With numerous manganese bronze castings presently in service in all 37 water distribution shafts in New York City, a stress-corrosion cracking test program has recently been initiated. The specimens used were of the modified compact wedge-loaded type made of CDA Alloy C86500. The purpose of the test was not only to find which distribution shafts contained an aggressive SCC environment, but to identify any corrosive agents in the shafts. All 37 shaft environments produced cracking in one or more of the specimens tested in 15 to 63 days. Most of the cracking occurred with the pH in the range from 7.5 to 9.5.
The spillage of elemental mercury from flowmeters in the shafts plus the introduction of chemicals used for mercury cleanup accelerated the SCC investigation. Mn-bronze specimens were tested in jars containing ammonia, mercury, water, trisodium phosphate, and commercial mercury cleaning solutions. All chemical induced cracking in the specimens in a range from 1 to over 300 days, except mercury and trisodium phosphate.
Scanning electron microscopy was used to characterize the crack pattern of several in-service failures and SCC test specimens. Energy-dispersive analysis was used to identify the corrosion products on the crack surfaces.
Erosion-Corrosion Measuring Devices
Authors: Schorr M , Weintraub E , Andrasi D 
Published: March 2009

Two instruments for the study and measurement of erosion-corrosion (EC) were developed and built: the erosion-corrosion unit (ECU) and the erosion-corrosion tester (ECT). These instruments simulate the shear and impact forces acting on industrial equipment to evaluate the corrosive wear effects of the fluid on the equipment and their interaction. The specimen in the ECU consists of a cylinder rotated about a vertical axis while a jet of slurry impinges continuously onto its curved surface through an interchangeable nozzle. The ECT applies rotational sliding abrasion by the slurry on a static disk specimen. In both devices, a three-electrode system (working, reference, and counter electrodes) is used to evaluate the electrochemical corrosion component by the polarization resistance technique. The contribution of mechanical erosion to the synergetic EC process is measured by weight loss on long-term exposures.
The instruments were applied as follows: in industrial plants to monitor the influence of corrosion parameters during production, in pilot plants and in the laboratory to evaluate and select corrosion-resistant alloys, to assess the corrosivity of the ores and slurries handled, and for analysis of EC failures.
The instruments are described and their characteristics compared. The results obtained in several environments are presented and their significance discussed.
Stress Corrosion Cracking in Alloy 400 (UNS NO4400) at Room Temperature
Authors: Everhart LG , Price CE 
Published: March 2009

Selective pitting studies were used to determine environments likely to cause stress corrosion cracking (SCC) in Alloy 400. Slow strain rate tests were performed on waisted specimens, with solution composition and concentration, strain rate, grain size, and prior cold work as variables. It was found that environments which caused pitting also caused SCC; examples include ammonium hydroxide, ammonium persulfate, and hydrofluoric acid in the presence of an oxidizer.
As in the case of both hydrogen and liquid metal embrittlement of Alloy 400 and other nickel-base alloys, the SCC at low strain levels was intergranular with a transition to transgranular at higher strains. The fractography of the SCC resembled that of the other embrittling environments.
Electrochemical Methods of Determining the Corrosivity of Steel in Concrete
Authors: Berke NS , Hicks MC 
Published: March 2009

Steel-reinforced concrete is used throughout the world in the construction of bridges, marine structures, parking garages, and buildings. The alkaline environment of the concrete protects the steel from corrosion; however, this protective environment can be disrupted due to the migration of chloride ions to the steel and/or to carbonation of the concrete. In this paper several electrochemical techniques that can be used to determine and predict the corrosion of steel in concrete are described. Further, it is shown how these techniques can be used to show the effectiveness of corrosion inhibitors and other modifications to the concrete mixture on corrosion control.
Solution testing in calcium hydroxide and in sodium/potassium hydroxide pore water solutions can be used to determine corrosion mechanisms and the effectiveness of inhibitors when chloride is present. The use of cyclic polarization in these solutions to determine the effects of chloride and calcium nitrite is discussed.
Corrosion testing of steel in concrete provides more direct evidence of the effect of the concrete mix design on corrosion performance. Three techniques are quite common in this laboratory and in others. They are polarization resistance, electrochemical impedance, and the measurement of the macrocell corrosion between two layers of bars. The use of these techniques is discussed, and several examples of their use and comparison to visual attack of the steel are given. The techniques, as used, correlate very well with the observed corrosion damage on the embedded steel.
Because polarization resistance and electrochemical impedance are nondestructive, they can be used to monitor the corrosion rates of steel in concrete, whereas mass loss or visual observation require destruction of the concrete to observe the bar. The use of these techniques to monitor the long-term behavior of steel in concrete is demonstrated.
Sensitivity analysis of pesticides contaminating groundwater by applying probability and transport methods
Authors: Zhang Pengxin , Aagaard Per , Nadim Farrokh , Gottschalk Lars , Haarstad Ketil 
Published: March 2009

Abstract
The use of pesticides is a potential threat to local groundwater. Once groundwater is contaminated, it is very difficult to clean. Thus, it is of importance to assess the risk of contaminating local groundwater at an early stage when pesticides are found in soils. This knowledge will also help in remediation strategies. Traditional methods of deterministic analysis cannot explicitly account for the sometimes large uncertainties that exist at this stage in the work, whereas probabilistic analyses are better suited for dealing with these problems. In this paper, we have combined contaminant transport with a 1st-order reliability approach. Pesticide concentrations in soil have been studied to estimate the probability of failure—that is, of pesticides exceeding established critical levels in groundwater. Results indict that failure probability increases rapidly within a certain range of pesticide concentrations in soil for different critical levels. In given aquifer conditions and contaminants, probabilities of contaminants exceeding particular critical levels can easily be obtained according to various water usage scenarios. The distribution of importance factors among variables indicates the contribution their relative weights make to the failure probability. Hence, authorities can easily form sensitivity factors to take action and reduce the risk of contaminating the groundwater.
Functional Programming
Authors: Chitil Olaf 
Published: March 2009

AbstractFunctional programming is a programming paradigm like object‐oriented programming and logic programming. Functional programming comprises both a specific programming style and a class of programming languages that encourage and support this programming style. Functional programming enables the programmer to describe an algorithm on a high level, in terms of the problem domain, without having to deal with machine‐related details. A program is constructed from functions that only map inputs to outputs, without any other effect on the program state. Thus, a function will always return the same output, regardless of when and in which context the function is used. These functions provide clear interfaces, separate concerns, and are easy to reuse. A small and simple set of highly orthogonal language constructs assists in writing modular programs.