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1

Halogen and LED light curing of composite: temperature increase and Knoop hardness  

Microsoft Academic Search

This study assessed the Knoop hardness and temperature increase provided by three light curing units when using (1) the manufacturers’\\u000a recommended times of photo-activation and (2) standardizing total energy density. One halogen – XL2500 (3M\\/ESPE) – and two\\u000a light-emitting diode (LED) curing units – Freelight (3M\\/ESPE) and Ultrablue IS (DMC) – were used. A type-K thermocouple registered\\u000a the temperature change

L. F. Schneider; S. Consani; L. Correr-Sobrinho; A. B. Correr; M. A. Sinhoreti

2006-01-01

2

Dentinal composition and Knoop hardness measurements of cavity floor following carious dentin removal with Carisolv.  

PubMed

This study evaluated the dentinal composition and Knoop hardness measurements of the cavity floor following the removal of carious dentin by the Carisolv chemo-mechanical caries removal system, in vitro. The carious dentin of 25 extracted human teeth was removed by using Carisolv for one minute with instruments and excavation that was performed until the gel was clear. Caries removal with a sharp explorer was verified according to the color and hardness of the lesion, then, by means of DIAGNOdent. Atomic analysis of treated cavities was performed by energy dispersive x-ray spectroscopy (SEM-EDX) and the Knoop hardness number (KHN) of the cavity floor was determined. Surface characteristics were observed by the scanning electron microscope (SEM). Adjacent sound dentin was used as a control reference. No significant differences were found between the quantities of calcium content (Ca weight %), phosphorus content (P weight %) and the Ca/P weight ratio of Carisolv cavities with that of the adjacent, sound dentin (p<0.01). KHN of the Carisolv cavity floor was almost similar to that of the adjacent sound dentin. SEM analysis revealed an extremely rough or irregular surface, and there remained a minimal debris-like smear layer; most of the dentinal tubules were opened. The results indicated that Carisolv does not produce any adverse side effects on dentinal compositions of the treated cavities. The possibility of remaining residual softened dentin was also minimal in this study. PMID:12877418

Hossain, Mozammal; Nakamura, Yukio; Tamaki, Yukimichi; Yamada, Yoshishige; Jayawardena, Jayanetti Asiri; Matsumoto, Koukichi

3

Effects of potassium oxalate on knoop hardness of etch-and-rinse adhesives.  

PubMed

The objective of this study was to determine whether the hardness of etch-and-rinse adhesives may be affected by the pretreatment of acid-etched dentin with potassium oxalate desensitizer. Unerupted human third molars were cut into crown segments by removing the occlusal enamel and roots. The pulp chamber of these crown segments was connected to a syringe barrel filled with phosphate-buffered saline so that the moisture of dentin was maintained during the bonding procedures. Three etch-and-rinse adhesives-two two-step systems (Adper Single Bond 2 [SB], One-Step [OS]) and one three-step system (Adper Scotchbond Multi-Purpose [MP])-were applied to acid-etched dentin that had been treated (experimental groups) or not (control groups) with potassium oxalate (BisBlock). The Knoop hardness (KHN) of adhesives was taken at different sites of the outer surface of the adhesive-bonded dentin. The KHN of the three tested adhesives applied to acid-etched dentin treated with potassium oxalate was significantly lower than that exhibited by the respective controls (not treated with oxalate; p<0.05). Regardless of the adhesive, the treatment with potassium oxalate reduced the adhesives' KHN (p<0.05), with the OS system exhibiting the lowest KHN compared with the MP and SB systems. PMID:22335301

Silva, S M A; Malacarne-Zanon, J; Carvalho, R M; Alves, M C; De Goes, M F; Anido-Anido, A; Carrilho, M R

2012-02-15

4

Effect of different light-curing devices and aging procedures on composite knoop microhardness.  

PubMed

The aim of this study was to evaluate the effect of light-curing devices (Halogen/HAL, Light Emitting Diodes/LED, Argon Laser/LAS and Plasma Arc/PAC) and aging procedures (Mechanical Cycling/MC, Thermal Cycling/TC, Storage/S, MC+TC and MC+TC+S) on the micro-hardness of bottom/B and top/T surfaces of 2-mm-high composite resin cylinders. The Knoop microhardness test (25 g, 20 s) on both B and T was performed before and after each aging procedure. For B and T, before aging procedures, PAC showed reduced polymerization effectiveness when compared with HAL. In the T, after TC, PAC and LAS had also showed reduced polymerization effectiveness when compared to HAL and LED. For all light-curing devices, MC+TC+S and S affected the Knoop microhardness values. In the B, no difference could be observed among the aging procedures for PAC. From all light-curing units, PAC may have rendered composites of reduced quality and the storage aging procedures were the most harmful to the polymer hardness. PMID:20027457

Voltarelli, Fernanda Regina; dos Santos-Daroz, Claudia Batitucci; Alves, Marcelo Corrêa; Peris, Alessandra Rezende; Marchi, Giselle Maria

5

Fabrication of Hard Glass Plates.  

National Technical Information Service (NTIS)

This report describes the fabrication of hard glass for use in ballistic application. The work consisted of establishing optimum composition and process conditions for several different glasses. Properties such as Knoop hardness, density, flexural strengt...

A. Z. Hed M. A. Ali

1974-01-01

6

Theoretical model of hardness anisotropy in brittle materials  

NASA Astrophysics Data System (ADS)

Anisotropy is prominent in the hardness test of single crystals. However, the anisotropic nature is not demonstrated quantitatively in previous hardness model. In this work, it is found that the electron transition energy per unit volume in the glide region and the orientation of glide region play critical roles in determining hardness value and hardness anisotropy for a single crystal material. We express the mathematical definition of hardness anisotropy through simple algebraic relations. The calculated Knoop hardnesses of the single crystals are in good agreement with observations. This theory, extended to polycrystalline materials by including hall-petch effect and quantum size effect, predicts that the polycrystalline diamond with low angle grain boundaries can be harder than single-crystal bulk diamond. Combining first-principles technique and the formula of hardness anisotropy the hardness of monoclinic M-carbon, orthorhombic W-carbon, Z-carbon, and T-carbon are predicted.

Gao, Faming

2012-07-01

7

Elastic modulus measurements via laser-ultrasonic and knoop indentation techniques in thermally sprayed coatings  

NASA Astrophysics Data System (ADS)

Nondestructive techniques for evaluating and characterizing coatings were extensively demanded by the thermal spray community; nonetheless, few results have been produced in practice due to difficulties in analyzing the complex structure of thermal spray coatings. Of particular interest is knowledge of the elastic modulus values and Poisson’s ratios, which are very important when seeking to understand and/or model the mechanical behavior or to develop life prediction models of thermal spray coatings used in various applications (e.g., wear, fatigue, and high temperatures). In the current study, two techniques, laser-ultrasonics and Knoop indentation, were used to determine the elastic modulus of thermal spray coatings. Laser-ultrasonics is a noncontact and nondestructive evaluation method that uses lasers to generate and detect ultrasound. Ultrasonic velocities in a material are directly related to its elastic modulus value. The Knoop indentation technique, which has been widely used as a method for determining elastic modulus values, was used to compare and validate the measurements of the laser-ultrasonic technique. The determination of elastic modulus values via the Knoop indentation technique is based on the measurement of elastic recovery of the dimensions of the Knoop indentation impression. The approach used in the current study was to focus on evaluating the elastic modulus of very uniform, dense, and near-isotropic titania and WC-Co thermal spray coatings using these two techniques. Four different coatings were evaluated: two titania coatings produced by air plasma spray (APS) and high-velocity oxyfuel (HVOF) and two types of WC-Co coatings, conventional and multimodal (nanostructured and microsized particles), deposited by HVOF.

Lima, R. S.; Kruger, S. E.; Lamouche, G.; Marple, B. R.

2005-03-01

8

Hardness anisotropy of SrF 2 , BaF 2 , NaCl and AgCl crystals  

Microsoft Academic Search

The value of Knoop microhardness was obtained for crystals of SrF2, BaF2, NaCl and AgCl by indentation in various directions on several crystallographic planes. In all cases, the hardness is essentially dependent on the crystallographic direction along the long axis of the indentor and independent of the plane of indentation, as first reported by Garfinkle and Garlick for other cubic

G. Y. Chin; M. L. Green; L. G. Uitert; W. A. Hargreaves

1973-01-01

9

Traceability in hardness measurements: from the definition to industry  

NASA Astrophysics Data System (ADS)

The measurement of hardness has been and continues to be of significant importance to many of the world's manufacturing industries. Conventional hardness testing is the most commonly used method for acceptance testing and production quality control of metals and metallic products. Instrumented indentation is one of the few techniques available for obtaining various property values for coatings and electronic products in the micrometre and nanometre dimensional scales. For these industries to be successful, it is critical that measurements made by suppliers and customers agree within some practical limits. To help assure this measurement agreement, a traceability chain for hardness measurement traceability from the hardness definition to industry has developed and evolved over the past 100 years, but its development has been complicated. A hardness measurement value not only requires traceability of force, length and time measurements but also requires traceability of the hardness values measured by the hardness machine. These multiple traceability paths are needed because a hardness measurement is affected by other influence parameters that are often difficult to identify, quantify and correct. This paper describes the current situation of hardness measurement traceability that exists for the conventional hardness methods (i.e. Rockwell, Brinell, Vickers and Knoop hardness) and for special-application hardness and indentation methods (i.e. elastomer, dynamic, portables and instrumented indentation).

Germak, Alessandro; Herrmann, Konrad; Low, Samuel

2010-04-01

10

Relation of Microindentation Hardness to Glass Composition.  

National Technical Information Service (NTIS)

Microindentation hardness measurements on Na2O-CaO-SiO2 and Na2O-Al2O3SiO2 glasses showed that Knoop hardness numbers are linearly related to oxide compositions expressed in mole fraction. Evaluations of the data indicate that these linear relations are u...

A. N. Georoff C. L. Babcock

1972-01-01

11

Impact of refrigeration on the surface hardness of hybrid and microfilled composite resins.  

PubMed

This in vitro study evaluated the Knoop hardness of the composite resins Charisma (C) and Durafill VS (D) polymerized in 3 different conditions: at room temperature (A) (23 +/- 1 degrees C); refrigerated at 4 +/- 1 degrees C and immediately photo-activated after removal from the refrigerator (0); and, refrigerated at 4 +/- 1 degrees C and photo-activated after a bench time of 15 min at room temperature (15). One hundred and twenty specimens (4 mm diameter and 2 mm depth) were made using a stainless steel mold and following manufacturer's instructions. All specimens were tested immediately after polymerization (I) and after 7 days of water storage in the dark at room temperature (7d). The data were subjected to ANOVA and post-hoc Tukey's test (alpha=0.05). On the top surface, C(AI) was statistically similar to C(15I) and D(AI) to D(15I) (p>0.05). On the bottom surface, C(AI) presented higher hardness values when compared to COI and C(15I) (p<0.05). The D groups showed no significant differences (p>0.05) on the bottom surfaces for any tested polymerization condition. After 7 days of storage, the Knoop hardness decreased significantly (p<0.05) for groups C(7d) and D(7d) except for C(07d), which was not different from C(OI) at either surface (p>0.05). D(07d) showed higher Knoop hardness (p<0.05) values on the top surface when compared to the other groups. PMID:19466230

Osternack, Fernando Henrique Ruppel; Caldas, Danilo Biazzetto de Menezes; Rached, Rodrigo Nunes; Vieira, Sérgio; Platt, Jeffrey A; Almeida, Janaina Bertoncelo de

2009-01-01

12

Knoop microhardness and FT-Raman evaluation of composite resins: influence of opacity and photoactivation source.  

PubMed

The aim of this study was to evaluate the degree of conversion by Knoop microhardness (KHN) and FT-Raman spectroscopy (FTIR) of one nanofilled (Filtek Supreme-3M-ESPE [FS]) and one microhybrid composite (Charisma-Heraeus-Kulzer [CH]), each with different opacities, namely enamel, dentin, and translucent, which were photo-activated by a quartz-tungsten-halogen lamp (QTH) and a light-emitting diode (LED). Resin was bulk inserted into a disc-shaped mold that was 2.0 mm thick and 4 mm in diameter, obtaining 10 samples per group. KHN and FTIR values were analyzed by two-way ANOVA and Tukey's tests (? = 0.05). Nanofilled resin activated by a LED presented higher microhardness values than samples activated by a QTH for dentin opacity (p < 0.05). The microhybrid resin showed no differences in KHN or FTIR values with different activation sources or opacity. The nanofilled dentin and enamel resins showed lower FTIR values than the translucent resin. The KHN values of the translucent resins were not influenced by the light source. PMID:21670859

Albino, Luis Gustavo Barrotte; Rodrigues, José Augusto; Kawano, Yoshio; Cassoni, Alessandra

13

Singular Value Decomposition of the Radial Distribution Function for Hard Sphere and Square Well Potentials  

PubMed Central

We compute the singular value decomposition of the radial distribution function for hard sphere, and square well solutions. We find that decomposes into a small set of basis vectors allowing for an extremely accurate representation at all interpolated densities and potential strengths. In addition, we find that the coefficient vectors describing the magnitude of each basis vector are well described by a low-order polynomial. We provide a program to calculate in this compact representation for the investigated parameter range.

Hoppe, Travis

2013-01-01

14

Diffusion and hardness studies in mercury zinc telluride  

SciTech Connect

We report studies of self-diffusion, interdiffusion, and hardness measurements in Hg{sub 1{minus}{ital x}}Zn{sub {ital x}}Te (MZT) in order to compare relative properties of Hg{sub 1{minus}{ital x}}Cd{sub {ital x}}Te (MCT) and MZT. Tracer diffusion behavior of MZT is similar to that of MCT, both in mechanism and in terms of diffusion quantities. Interdiffusion behavior in MZT is similar to that of MCT at low {ital x} values and shows a significant decrease with increasing {ital x}, but is less {ital x} dependent at high {ital x} values than in MCT. The self and interdiffusion results in MZT at low {ital x} values are related with a Nernst--Planck type of equation. The interdiffusion quantities in MZT are only marginally lower than in MCT for the conditions studied. Hardness values are determined as a function of composition in isothermal vapor phase epitaxial (ISOVPE) and horizontal liquid phase epitaxial (HLPE) MCT and MZT using a Vickers tester, a Knoop tester, and a Nanoindenter. There is a substantial increase of the hardness of MZT over that of MCT. Although hardening enhancement by alloying produces bowing in the hardness values as a function of composition in both MZT and MCT, the bowing is significantly more pronounced in the MZT system. In summary, MZT seems to have significant advantages over MCT with regard to improved hardness, but only a marginal difference in diffusion behavior.

Fang, S.; Farthing, L.J.; Tang, M.S.; Stevenson, D.A. (Department of Materials Science, Stanford, California (USA) Engineering, Stanford University, Stanford, California 94305 (US))

1990-03-01

15

Singular value decomposition of the radial distribution function for hard sphere and square well potentials.  

PubMed

We compute the singular value decomposition of the radial distribution function [Formula: see text] for hard sphere, and square well solutions. We find that [Formula: see text] decomposes into a small set of basis vectors allowing for an extremely accurate representation at all interpolated densities and potential strengths. In addition, we find that the coefficient vectors describing the magnitude of each basis vector are well described by a low-order polynomial. We provide a program to calculate [Formula: see text] in this compact representation for the investigated parameter range. PMID:24143174

Hoppe, Travis

2013-10-15

16

Applying Critical Thinking Skills to Character Education and Values Clarification with Students Who Are Deaf or Hard of Hearing  

ERIC Educational Resources Information Center

|Students who are deaf or hard of hearing must learn to think critically. "Character education" (CE) refers to the effort to teach basic values and moral reasoning (Doyle & Ponder, 1977). "Values clarification" (VC) is the process of examining one's basic values and moral reasoning (Rokeach, 1973). Character education and values clarification as…

Easterbrooks, Susan R.; Scheetz, Nanci A.

2004-01-01

17

Applying critical thinking skills to character education and values clarification with students who are deaf or hard of hearing.  

PubMed

Students who are deaf or hard of hearing must learn to think critically. Character education (CE) refers to the effort to teach basic values and moral reasoning (Doyle & Ponder, 1977). Values clarification (VC) is the process of examining one's basic values and moral reasoning (Rokeach, 1973). Character education and values clarification as subject matter foster the development of critical thinking (CT), a tool used both to develop and to modify values and moral reasoning. These three areas mutually support one another. The development of a set of values and their underlying moral reasoning is the foundation for thinking critically about values. The authors examine the components of critical thinking, character education, and values clarification, summarize the literature, and provide a template for appropriate lesson plans. They also describe strategies that promote the development of critical thinking, character education, and values clarification. PMID:15552336

Easterbrooks, Susan R; Scheetz, Nanci A

2004-01-01

18

Exploration of NP-hard Enumeration Problems by Simulated Annealing - the Spectrum Values of Permanents  

Microsoft Academic Search

The Monte Carlo optimisation technique simulated annealing has been used to sample the possible values of the permanent of fully indecomposable (0,l )-matrices. The basic idea in simulated annealing is that a Markov chain explores the space of feasible solutions, each of which has an associated \\

Yaghout Nourani; Bjarne Andresen

1999-01-01

19

Finite element analysis of stresses in Berkovich, Vickers and Knoop indentation for densifying and non-densifying glasses  

Microsoft Academic Search

A constitutive law for fused silica accounting for its permanent densification under large compressive stresses is presented. The implementation of the constitutive equations in the general-purpose finite element code ABAQUS via user subroutine is proposed and carefully verified. The three-dimensional indentation mechanics under Berkovich, Vickers and Knoop indenters is extensively investigated based on the proposed constitutive relation. The results of

Kanghua Chen

2002-01-01

20

Chemical compositions and nutritional value of Asian hard clam (Meretrix lusoria) from the coast of Andaman Sea.  

PubMed

Chemical compositions and nutritive value of the edible portions including foot, mantle and viscera of Asian hard clam (Meretrix lusoria) harvested from the coast of Andaman Sea were determined. Proximate compositions varied with portions tested. Edible portions had moisture (76.23-84.22%) and protein (9.09-12.75%) as the major components. Carbohydrate (0.32-7.89%), fat (1.58-6.58%) and ash (1.23-2.58%) were also found at various levels, dependent upon portions. Myofibrillar proteins were observed as the major fraction in foot (40.54%) and mantle (31.65%), whilst non-protein nitrogen constituents were dominant in the viscera (36.85%). All portions contained a large amount of essential amino acids (167.66-187.63mg/g sample), in which leucine (30.91-36.96mg/g sample) and lysine (35.24-36.03mg/g sample) were predominant. They were rich in polyunsaturated fatty acids (46.84-49.18% of total fatty acid) with high level of DHA (13.33-16.47 % of total fatty acids) and EPA (4.75-7.11% of total fatty acids). Cholesterol of 0.07-0.21% wet weight was detected. All portions were also rich in macro- (Na, K, Ca and Mg) and micro- (Fe, Zn, Cu and Cr) minerals. Therefore, Asian hard clam is an excellent source of several nutrients, which could be beneficial for the health of the consumers. PMID:23993597

Karnjanapratum, Supatra; Benjakul, Soottawat; Kishimura, Hideki; Tsai, Yung-Hsiang

2013-07-08

21

Hardness, polymerization depth, and internal adaptation of Class II silorane composite restorations as a function of polymerization protocol  

PubMed Central

Objectives: To evaluate the influence of various photoactivation techniques on the internal gap, Knoop-hardness, and polymerization depth of silorane- and methacrylate-based composites in Class II restorations. Methods: Preparations were made in third molars (n = 10), according to composites (Filtek P60: methacrylate; Filtek P90: silorane) and photoactivation techniques (OC: occlusal photoactivation (control); OBL: occlusal+buccal+lingual photoactivation; and BLO: buccal+lingual+occlusal photoactivation (transdental)). Composites were inserted in two increments, both individually photoactivated for 20s. After 24h, specimens were sectioned and the ratio of internal gaps to interface length (%) recorded. Hardness was tested across the transversal section of restorations (1–4 mm below the surface). Results: Silorane restorations showed significantly lower gaps compared with methacrylate, regardless of polymerization technique (P<.05). Supplementary energy dose in OBL and BLO protocols caused significant increase in gaps in silorane restorations (P<.05). For methacrylate restorations, OBL activation caused significantly higher gap formation (P<.05). Significantly lower hardness values were seen for silorane than for methacrylate composites (P<.05), regardless of depth and photoactivation. Significantly higher hardness values were seen in BLO activation for methacrylate restorations compared with control (P<.05); for silorane, no differences were observed. Significantly higher hardness values were observed at 1 and 3 mm compared to 2 and 4 mm for both composites. Conclusions: Internal gaps and hardness are affected by composite type and photoactivation. Despite the reduced values, hardness of silorane is not influenced by photoactivation or by depth. Internal gaps are dependent on the energy dose for both composites, with silorane showing lower internal gaps.

Bechtold, Janaina; dos Santos, Priscila Jaques; Anido-Anido, Andrea; Di Hipolito, Vinicius; Alonso, Roberta Caroline Bruschi; D'Alpino, Paulo Henrique Perlatti

2012-01-01

22

Knoop hardness of ten resin composites irradiated with high-power LED and quartz-tungsten-halogen lights  

Microsoft Academic Search

This study compared a high-power light-emitting-diode (LED) curing light (FreeLight 2, 3M ESPE) with a quartz-tungsten-halogen (QTH) light (TriLight, 3M ESPE) to determine which was the better at photo-polymerising 10 resin composites. Class I preparations were prepared 4-mm deep into human teeth and filled with 10 different composites. The composites were irradiated for 50% or 100% of their recommended times

Richard B. T. Price; Corey A. Felix; Pantelis Andreou

2005-01-01

23

A Terrible Predicament: The De-Evolution of Values in Flannery O'Connor's "A Good Man Is Hard to Find."  

ERIC Educational Resources Information Center

Addresses problems concerning the ways Flannery O'Connor's fiction has been read. Proposes an alternate reading of "A Good Man Is Hard to Find." Suggests the primary theme of the story is the idea that each generation has the responsibility to pass on values to the next. (PM)

Tietz, Stephen; Logsdon, Loren

2001-01-01

24

A Terrible Predicament: The De-Evolution of Values in Flannery O'Connor's "A Good Man Is Hard to Find."  

ERIC Educational Resources Information Center

|Addresses problems concerning the ways Flannery O'Connor's fiction has been read. Proposes an alternate reading of "A Good Man Is Hard to Find." Suggests the primary theme of the story is the idea that each generation has the responsibility to pass on values to the next. (PM)|

Tietz, Stephen; Logsdon, Loren

2001-01-01

25

Be hard on the interests and soft on the values: conflict issue moderates the effects of anger in negotiations.  

PubMed

Emotions play an important role in conflict resolution. Past work has found that negotiators tend to concede when confronted with anger. We argue and show that this effect occurs in conflicts about interests, but not in conflicts about values. In value conflicts that are more closely tied to a person's values, norms, and identity, expressions of anger are likely to backfire. We demonstrate that people deem expressions of anger more unfair in value conflicts than in interest conflicts (Study 1) and that they are more likely to engage in retaliatory and escalatory behaviours when confronted with an angry reaction in the context of a value issue rather than an interest issue (Study 2). PMID:22283784

Harinck, Fieke; Van Kleef, Gerben A

2012-01-27

26

Depth of cure and hardness of indirect composite materials polymerized with two metal halide laboratory curing units.  

PubMed

The purpose of this study was to evaluate the depth of cure and Knoop hardness of indirect composite materials polymerized with different laboratory curing units. Five composite materials designed for fixed restoration veneer (Artglass, Ceramage, Epricord, Prossimo, and Solidex) were filled into a cylindrical mold and then light-exposed by using the respective proprietary laboratory curing unit or two metal halide curing units (Hyper LII and Twinkle X). Depth of cure was determined by a scraping technique, as described in ISO 4049. Composites also underwent Knoop hardness testing after immersion in water. The results (n = 5) were analyzed with the Kruskal-Wallis test and Dunn's multiple comparison test. For three materials (Prossimo, Artglass, and Epricord), depth of cure after polymerization with the Twinkle X unit was greater than that after polymerization with the respective proprietary units. For the Ceramage and Artglass materials, the Twinkle X unit resulted in the highest Knoop hardness number (KHN), whereas, for the Prossimo material, the Hyper LII unit resulted in the highest KHN. The metal halide units were effective in enhancing the post-polymerization properties of specific composite materials while reducing exposure time. PMID:22466896

Nishimaki, Mariko

2012-03-01

27

The Aesthetic Value of Littoral Hard Substrata and Consideration of Ethical Frameworks for Their Investigation and Conservation  

Microsoft Academic Search

\\u000a Rocky coastlines provide impressive vistas. The recreational and aesthetic value of rocky intertidal areas encompasses a large\\u000a proportion of their ecosystem services, along with provisioning and regulatory services such as nutrient regulation and supply\\u000a of food. Ethical considerations are confusing but critical to any discussions on the use of rocky shores. We must ensure an\\u000a appropriate mix between exploitation (e.g.

Heather E. Sugden; A. J. Underwood; Stephen J. Hawkins

28

Comparison between a plasma arc light source and conventional halogen curing units regarding flexural strength, modulus, and hardness of photoactivated resin composites  

Microsoft Academic Search

The plasma arc curing light Apollo 95 E (DMDS) is compared to conventional curing lights of different radiation intensities\\u000a (Vivalux, Vivadent, 250 mW\\/cm2; Spectrum, DeTrey, 550 mW\\/cm2; Translux CL, Kulzer, 950 mW\\/cm2). For this purpose, photoactivated resin composites were irradiated using the respective curing lights and tested for flexural\\u000a strength, modulus of elasticity (ISO 4049), and hardness (Vickers, Knoop) 24

N. Hofmann; B. Hugo; K. Schubert; B. Klaiber

2000-01-01

29

Hybrid hard- and soft-modeling of spectrophotometric data for monitoring of ciprofloxacin and its main photodegradation products at different pH values  

NASA Astrophysics Data System (ADS)

A simple and fast on line spectrophotometric method combined with a hybrid hard-soft modeling multivariate curve resolution (HS-MCR) was proposed for the monitoring of photodegradation reaction of ciprofloxacin under UV radiation. The studied conditions attempt to emulate the effect of sunlight on these antibiotics that could be eventually present in the environment. The continuous flow system made it possible to study the ciprofloxacin degradation at different pH values almost at real time, avoiding errors that could arise from typical batch monitoring of the reaction. On the base of a concentration profiles obtained by previous pure soft-modeling approach, reaction pathways have been proposed for the parent compound and its photoproducts at different pH values. These kinetic models were used as a constraint in the HS-MCR analysis. The kinetic profiles and the corresponding pure response profile (UV-Vis spectra) of ciprofloxacin and its main degradation products were recovered after the application of HS-MCR analysis to the spectra recorded throughout the reaction. The observed behavior showed a good agreement with the photodegradation studies reported in the bibliography. Accordingly, the photodegradation reaction was studied by high performance liquid chromatography coupled with UV-Vis diode array detector (HPLC-DAD). The spectra recorded during the chromatographic analysis present a good correlation with the ones recovered by UV-Vis/HS-MCR method.

Razuc, Mariela; Garrido, Mariano; Caro, Yamile S.; Teglia, Carla M.; Goicoechea, Héctor C.; Fernández Band, Beatriz S.

2013-04-01

30

Evaluation of hardness and fracture toughness, coupled with microstructural analysis, of zirconia ceramics stored in environments with different pH values.  

PubMed

The aim of this study was to evaluate the effects of pH changes in the oral cavity on the mechanical properties of zirconia and feldspathic ceramics. Bilayered zirconia-feldspathic samples were prepared from three different commercial brands of Y-TZP blocks: Zirkonzahn, Cercon, and Everest. Samples were stored in artificial saliva with different pH values (3.5, 7.0, and 10.0) for 10 days at 37°C. Flexural strength, Vickers hardness, and fracture toughness were calculated after samples were subjected to biaxial flexure test. Microstructural analysis of the materials was also performed.Data were analyzed by one-way analysis of variance (ANOVA), and multiple comparisons were performed using Tukey's test (?=0.05). Acidic and alkaline environments adversely affected the mechanical properties of zirconia, resulting in material degradation, loss of stabilizer content, and increase in tetragonal-monoclinic phase transformation. Commercial dental zirconia blocks have varied mechanical properties, but they are generally susceptible to degradation when exposed to corrosive environments. PMID:23207192

Turp, Volkan; Tuncelli, Betul; Sen, Deniz; Goller, Gultekin

2012-01-01

31

Young's modulus and fracture during Knoop indentation of potassium, rubidium, cesium, and ammonium acid phthalate single crystals on the (010) plane  

NASA Astrophysics Data System (ADS)

The correlation of the anisotropy of the Young's modulus of organic single crystals of potassium, rubidium, cesium, and ammonium acid phthalates with strain and fracture patterns during Knoop indentation on the (010) cleavage plane in the [001] and [100] directions has been studied. The data on the maximum anisotropy of the strain and fracture patterns of the ammonium acid phthalate single crystal have been discussed in view of the published data on the structure, mechanical, elastic, and X-ray spectral properties of these crystals.

Sizova, N. L.; Moiseeva, N. A.

2012-12-01

32

Using Plasticity Values Determined From Systematic Hardness Indentation Measurements for Predicting Impact Behavior in Structural Ceramics: A New, Simple Screening Technique.  

National Technical Information Service (NTIS)

In general, it has long been known that the hardness of ceramics correlates with gross impact performance, however, not to a degree useful for materials development. Wilkins, Cline and Honodel, 1969, were the first to point out the apparent importance of ...

J. W. McCauley T. E. Wilantewicz

2009-01-01

33

Effect of light energy density on conversion degree and hardness of dual-cured resin cement.  

PubMed

This study evaluated the effect of different light energy densities on conversion degree (CD) and Knoop hardness number (KHN) of RelyX ARC (RLX) resin cement. After manipulation according to the manufacturer's instructions, RLX was inserted into a rubber mold (0.8 mm x 5 mm) and covered with a Mylar strip. The tip of the light-curing unit (LCU) was positioned in contact with the Mylar surface. Quartz-tungsten-halogen (QTH) and light-emitting diode (LED) LCUs with light densities of 10, 20 and 30 J/cm2 were used to light-cure the specimens. After light curing, the specimens were stored dry in lightproof containers at 37 degrees C. After 24 hours, the CD was analyzed by FT-Raman and, after an additional 24-hours, samples were submitted to Knoop hardness testing. The data of the CD (%) and KHN were submitted to two-way ANOVA and the Tukey's test (alpha = 0.05). QTH and LED were effective light curing units. For QTH, there were no differences among the light energy densities for CD or KHN. For LED, there was a significant reduction in CD with the light energy density set at 10 J/cm2. KHN was not influenced by the light-curing unit and by its light energy density. PMID:20166419

Komori, Paula Carolina de Paiva; de Paula, Andréia Bolzan; Martin, Airton Abr?o; Tango, Rubens Nisie; Sinhoreti, Mario Alexandre Coelho; Correr-Sobrinho, Lourenço

34

Effect of metal halide light source on hardness, water sorption and solubility of indirect composite material.  

PubMed

This study evaluates the effects of a metal halide light source on the post-polymerization properties of the Sinfony indirect composite material. Two polymerization systems were employed: the Hyper LII system, comprising a metal halide polymerization unit, and the Visio system, comprising two proprietary units designed for polymerizing the Sinfony composite. The composite material was polymerized for 60, 120 or 180 s with the LII system. As a control, the composite was polymerized for 15 min with the Visio system. Knoop hardness, water sorption and solubility were determined. The results were analyzed by Dunnett's T3 multiple comparison test (P<0.05). Knoop hardness was greater for polymerization with the LII unit than for that with the Visio system. Water sorption was greater for polymerization with the Visio system than that with the LII unit. For polymerization with the LII unit for 180 s, solubility was significantly reduced as compared with the Visio system. Within the limitations of the current experiment, it can be concluded that the metal halide unit exhibited better polymerizing performance for the composite material than the proprietary units. PMID:16415559

Koizumi, Hiroyasu; Satsukawa, Hidetada; Tanoue, Naomi; Ogino, Tomohisa; Nishiyama, Minoru; Matsumura, Hideo

2005-12-01

35

Microindentation hardness evaluation of iridium alloy clad vent set cups  

SciTech Connect

An iridium alloy, DOP-26, is used as cladding for {sup 238}PuO{sup 2} fuel in radioisotope heat sources for space power systems. Presently, DOP-26 iridium alloy clad vent sets (CVS) are being manufactured at the Oak Ridge Y-12 Plant for potential use in the National Aeronautics and Space Administration's Cassini mission to Saturn. Wrought/ground/stress relieved blanks are warm formed into CVS cups. These cups are then annealed to recrystallize the material for subsequent fabrication/assembly operations as well as for final use. One of the cup manufacturing certification requirements is to test for Vickers microindentation hardness. New microindentation hardness specification limits, 210 to 310 HV, have been established for a test load of 1000 grams-force (gf). The original specification limits, 250 to 350 HV, were for 200 gf testing. The primary reason for switching to a higher test load was to reduce variability in the test data. The DOP-26 alloy exhibits microindentation hardness load dependence, therefore, new limits were needed for 1000 gf testing. The new limits were established by testing material from 15 CVS cups using 200 gf and 1000 gf loads and then statistically analyzing the data. Additional work using a Knoop indenter and a 10 gf load indicated that the DOP-26 alloy grain boundaries have higher hardnesses than the grain interiors.

Ulrich, G.B.; DeRoos, L.F.; Stinnette, S.E.

1992-05-15

36

Microindentation hardness evaluation of iridium alloy clad vent set cups  

SciTech Connect

An iridium alloy, DOP-26, is used as cladding for [sup 238]PuO[sub 2] fuel in radioisotope heat sources for space power systems. Presently, DOP-26 iridium alloy clad vent sets (CVS) are being manufactured at the Oak Ridge Y-12 Plant for potential use in the National Aeronautics and Space Administration's Cassini mission to Saturn. Wrought/ground/stress relieved blanks are warm formed into CVS cups. These cups are then annealed to recrystallize the material for subsequent fabrication/assembly operations as well as for final use. One of the cup manufacturing certification requirements is to test for Vickers microindentation hardness. New microindentation hardness specification limits, 210 to 310 HV, have been established for a test load of 1000 grams-force (gf). The original specification limits, 250 to 350 HV, were for 200 gf testing. The primary reason for switching to a higher test load was to reduce variability in the test data. The DOP-26 alloy exhibits microindentation hardness load dependence, therefore, new limits were needed for 1000 gf testing. The new limits were established by testing material from 15 CVS cups using 200 gf and 1000 gf loads and then statistically analyzing the data. Additional work using a Knoop indenter and a 10 gf load indicated that the DOP-26 alloy grain boundaries have higher hardnesses than the grain interiors.

Ulrich, G.B.; DeRoos, L.F.; Stinnette, S.E. (Oak Ridge Y-12 Plant, P.O. Box 2009, Oak Ridge, Tennessee 37831-8096 (United States))

1993-01-15

37

Microindentation hardness evaluation of iridium alloy clad vent set cups  

SciTech Connect

An iridium alloy, DOP-26, is used as cladding for {sup 238}PuO{sup 2} fuel in radioisotope heat sources for space power systems. Presently, DOP-26 iridium alloy clad vent sets (CVS) are being manufactured at the Oak Ridge Y-12 Plant for potential use in the National Aeronautics and Space Administration`s Cassini mission to Saturn. Wrought/ground/stress relieved blanks are warm formed into CVS cups. These cups are then annealed to recrystallize the material for subsequent fabrication/assembly operations as well as for final use. One of the cup manufacturing certification requirements is to test for Vickers microindentation hardness. New microindentation hardness specification limits, 210 to 310 HV, have been established for a test load of 1000 grams-force (gf). The original specification limits, 250 to 350 HV, were for 200 gf testing. The primary reason for switching to a higher test load was to reduce variability in the test data. The DOP-26 alloy exhibits microindentation hardness load dependence, therefore, new limits were needed for 1000 gf testing. The new limits were established by testing material from 15 CVS cups using 200 gf and 1000 gf loads and then statistically analyzing the data. Additional work using a Knoop indenter and a 10 gf load indicated that the DOP-26 alloy grain boundaries have higher hardnesses than the grain interiors.

Ulrich, G.B.; DeRoos, L.F.; Stinnette, S.E.

1992-05-15

38

Evaluation of absolute hardness: a new approach.  

PubMed

By taking the energy to be a Morse-like function of the number of electrons, E(N) = ?{1 - e(-?(N-?))}(2) - ?, the electronic chemical potential and global hardness values for a set of atoms and some molecules are calculated from the accurate definitions of these two concepts and using the hybrid B3LYP functional and 6-311++G** basis set. By a comparison between the obtained hardnesses and the corresponding experimental values, it is found that the proposed model yields better values for hardnesses with respect to those that are obtained from the other frequently used methods. It is claimed that the difference between the calculated and experimental hardness values may arise from the approximate equation used for the evaluation of experimental hardnesses. Both of the calculated and experimental molecular hardnesses are used to investigate the change of hardness during the course of some exothermic reactions according to the maximum hardness principle (MHP). It is shown that the obtained hardnesses of reactions from the calculated hardnesses (??(calc)) are more successful in predicting the directions of these reactions than those that are evaluated from the experimental hardnesses (??(exp)). PMID:23360416

Noorizadeh, Siamak; Parsa, Hadi

2013-01-29

39

SUPER HARD SURFACED POLYMERS  

SciTech Connect

High energy ion beam surface treatments were applied to a selected group of polymers. Of the six materials in the present study, four were thermoplastics (polycarbonate, polyethylene, polyethylene terephthalate, and polystyrene) and two were thermosets (epoxy and polyimide). The particular epoxy evaluated in this work is one of the resins used in formulating fiber reinforced composites for military helicopter blades. Measures of mechanical properties of the near surface regions were obtained by nanoindentation hardness and pin on disk wear. Attempts were also made to measure erosion resistance by particle impact. All materials were hardness tested. Pristine materials were very soft, having values in the range of approximately 0.1 to 0.5 GPa. Ion beam treatment increased hardness by up to 50 times compared to untreated materials. For reference, all materials were hardened to values higher than those typical of stainless steels. Wear tests were carried out on three of the materials, PET, PI and epoxy. On the ion beam treated epoxy no wear could be detected, whereas the untreated material showed significant wear.

Mansur, Louis K [ORNL; Bhattacharya, R [UES, Incorporated, Dayton, OH; Blau, Peter Julian [ORNL; Clemons, Art [ORNL; Eberle, Cliff [ORNL; Evans, H B [UES, Incorporated, Dayton, OH; Janke, Christopher James [ORNL; Jolly, Brian C [ORNL; Lee, E H [Consultant, Milpitas, CA; Leonard, Keith J [ORNL; Trejo, Rosa M [ORNL; Rivard, John D [ORNL

2010-01-01

40

Microscopic models of hardness  

Microsoft Academic Search

Recent developments in the field of microscopic hardness models have been reviewed. In these models, the theoretical hardness\\u000a is described as a function of the bond density and bond strength. The bond strength may be characterized by energy gap, reference\\u000a potential, electron-holding energy or Gibbs free energy, and different expressions of bond strength may lead to different\\u000a hardness models. In

F. M. Gao; L. H. Gao

2010-01-01

41

Hardness of group IVA and IVB nitrides  

NASA Astrophysics Data System (ADS)

The hardnesses of various phases of group IVA and IVB nitrides (M3N4, M=C, Si, Ge, Sn, Ti, Zr or Hf; MN, M=Ti, Zr or Hf) were calculated using the bond electronegativity model for material hardness. The hardnesses of group IV nitrides increase with an increase in their average coordination numbers except for carbon nitrides, for which increasing the average coordination numbers results in a reduction in hardness. We suggest that for light-element compounds, the diamond-like structure represents the hardest one among all possible structures, whereas a high coordination number is generally required for heavy-element compounds to achieve high hardness values. This work provides a useful guide for designing novel nitride materials having excellent mechanical performances.

Li, Keyan; Xue, Dongfeng

2010-05-01

42

How Hard is Chocolate?  

NSDL National Science Digital Library

Hardness is probably a concept you are well familiar with. You already know that certain materials are harder than others; in fact, you prove it everyday when you chew your food and your teeth don’t break (because your teeth are harder than the foods you chew). Hardness can be defined as a material's ability to resist a change in shape. Modern hardness testers take a well-defined shape and press it into a material with a certain force, observing the indent it leaves in the material when it is removed. In this lesson, you will be performing hardness testing on different bars of chocolate.

2007-12-20

43

Ordering of hard particles between hard walls  

NASA Astrophysics Data System (ADS)

The structure of a fluid of hard Gaussian overlap particles of elongation ? = 5, confined between two hard walls, has been calculated from density-functional theory and Monte Carlo simulations. By using the exact expression for the excluded volume kernel (Velasco E and Mederos L 1998 J. Chem. Phys. 109 2361) and solving the appropriate Euler-Lagrange equation entirely numerically, we have been able to extend our theoretical predictions into the nematic phase, which had up till now remained relatively unexplored due to the high computational cost. Simulation reveals a rich adsorption behaviour with increasing bulk density, which is described semi-quantitatively by the theory without any adjustable parameters.

Chrzanowska, A.; Teixeira, P. I. C.; Ehrentraut, H.; Cleaver, D. J.

2001-05-01

44

Session: Hard Rock Penetration  

SciTech Connect

This session at the Geothermal Energy Program Review X: Geothermal Energy and the Utility Market consisted of five presentations: ''Hard Rock Penetration - Summary'' by George P. Tennyson, Jr.; ''Overview - Hard Rock Penetration'' by James C. Dunn; ''An Overview of Acoustic Telemetry'' by Douglas S. Drumheller; ''Lost Circulation Technology Development Status'' by David A. Glowka; ''Downhole Memory-Logging Tools'' by Peter Lysne.

Tennyson, George P. Jr.; Dunn, James C.; Drumheller, Douglas S.; Glowka, David A.; Lysne, Peter

1992-01-01

45

Hardness methods for testing maize kernels.  

PubMed

Maize is a highly important crop to many countries around the world, through the sale of the maize crop to domestic processors and subsequent production of maize products and also provides a staple food to subsistance farms in undeveloped countries. In many countries, there have been long-term research efforts to develop a suitable hardness method that could assist the maize industry in improving efficiency in processing as well as possibly providing a quality specification for maize growers, which could attract a premium. This paper focuses specifically on hardness and reviews a number of methodologies as well as important biochemical aspects of maize that contribute to maize hardness used internationally. Numerous foods are produced from maize, and hardness has been described as having an impact on food quality. However, the basis of hardness and measurement of hardness are very general and would apply to any use of maize from any country. From the published literature, it would appear that one of the simpler methods used to measure hardness is a grinding step followed by a sieving step, using multiple sieve sizes. This would allow the range in hardness within a sample as well as average particle size and/or coarse/fine ratio to be calculated. Any of these parameters could easily be used as reference values for the development of near-infrared (NIR) spectroscopy calibrations. The development of precise NIR calibrations will provide an excellent tool for breeders, handlers, and processors to deliver specific cultivars in the case of growers and bulk loads in the case of handlers, thereby ensuring the most efficient use of maize by domestic and international processors. This paper also considers previous research describing the biochemical aspects of maize that have been related to maize hardness. Both starch and protein affect hardness, with most research focusing on the storage proteins (zeins). Both the content and composition of the zein fractions affect hardness. Genotypes and growing environment influence the final protein and starch content and, to a lesser extent, composition. However, hardness is a highly heritable trait and, hence, when a desirable level of hardness is finally agreed upon, the breeders will quickly be able to produce material with the hardness levels required by the industry. PMID:19496585

Fox, Glen; Manley, Marena

2009-07-01

46

Hard Probes 2006: Theoretical Summary  

NASA Astrophysics Data System (ADS)

What makes a hard process a hard probe of hot and dense nuclear matter? In the context of this question, I review recent results shown by the theory speakers at the 2nd Hard Probes Conference in Asilomar.

Wiedemann, Urs Achim

2007-02-01

47

Radiation from hard objects  

SciTech Connect

The inference of the diameter of hard objects is insensitive to radiation efficiency. Deductions of radiation efficiency from observations are very sensitive - possibly overly so. Inferences of the initial velocity and trajectory vary similarly, and hence are comparably sensitive.

Canavan, G.H.

1997-02-01

48

What Would You Work Hard For?  

NSDL National Science Digital Library

This lesson plan helps young children begin to learn about the concept of value and why some items are considered more valuable than others. These concepts relate to a geographical understanding of natural resources and the reasons why people work very hard to extract resources, such as during the California gold rush. This lesson has students go through a simulation to learn about value, abundance, and scarcity and asks them to consider the things that they would be willing to work very hard for.

49

Polydisperse hard spheres at a hard wall  

NASA Astrophysics Data System (ADS)

The structural properties of polydisperse hard spheres in the presence of a hard wall are investigated via Monte Carlo simulation and density functional theory (DFT). Attention is focused on the local density distribution ?(?,z), measuring the number density of particles of diameter ? at a distance z from the wall. Estimates of ?(?,z) are obtained for bulk volume fractions ?b=0.2 and ?b=0.4, and for two choices of the bulk parent distribution: a top-hat form, which we study for degrees of polydispersity ?=11.5% and ?=40.4%, and a truncated Schulz form having ?=40.7%. Excellent overall agreement is found between the DFT and simulation results, particularly at ?b=0.2. A detailed analysis of ?(?,z) confirms the presence of oscillatory size segregation effects, as observed in a previous DFT study [I. Pagonabarraga, M. E. Cates, and G. J. Ackland, Phys. Rev. Lett. 84, 911 (2000)]. For large ?, the character of these oscillation is observed to depend strongly on the shape of the parent distribution. In the vicinity of the wall, attractive ?-dependent depletion interactions are found to greatly enhance the density of the largest particles. The local degree of polydispersity ?(z) is suppressed in this region, while further from the wall it exhibits oscillations.

Buzzacchi, Matteo; Pagonabarraga, Ignacio; Wilding, Nigel B.

2004-12-01

50

Potential Supply and Demand for Apple and Cherry-Apple Hard Cider Markets in Michigan, and Constraints to Market Development  

Microsoft Academic Search

The current research explores the potential to develop a cherry-apple hard cider market as a potential means to increase demand for and the value of Michigan fruit grower's product. Factors affecting both the development of hard cider markets in Michigan and cherry-apple hard cider were explored. Research results show that the potential value of Michigan hard cider market is relatively

Denise Y. Mainville; H. Christopher Peterson

2005-01-01

51

Hard superconducting nitrides  

PubMed Central

Detailed study of the equation of state, elasticity, and hardness of selected superconducting transition-metal nitrides reveals interesting correlations among their physical properties. Both the bulk modulus and Vickers hardness are found to decrease with increasing zero-pressure volume in NbN, HfN, and ZrN. The computed elastic constants from first principles satisfy c11 > c12 > c44 for NbN, but c11 > c44 > c12 for HfN and ZrN, which are in good agreement with the neutron scattering data. The cubic ?-NbN superconducting phase possesses a bulk modulus of 348 GPa, comparable to that of cubic boron nitride, and a Vickers hardness of 20 GPa, which is close to sapphire. Theoretical calculations for NbN show that all elastic moduli increase monotonically with increasing pressure. These results suggest technological applications of such materials in extreme environments.

Chen, Xiao-Jia; Struzhkin, Viktor V.; Wu, Zhigang; Somayazulu, Maddury; Qian, Jiang; Kung, Simon; Christensen, Axel N?rlund; Zhao, Yusheng; Cohen, Ronald E.; Mao, Ho-kwang; Hemley, Russell J.

2005-01-01

52

Hard superconducting nitrides.  

PubMed

Detailed study of the equation of state, elasticity, and hardness of selected superconducting transition-metal nitrides reveals interesting correlations among their physical properties. Both the bulk modulus and Vickers hardness are found to decrease with increasing zero-pressure volume in NbN, HfN, and ZrN. The computed elastic constants from first principles satisfy c11 > c12 > c44 for NbN, but c11 > c44 > c12 for HfN and ZrN, which are in good agreement with the neutron scattering data. The cubic delta-NbN superconducting phase possesses a bulk modulus of 348 GPa, comparable to that of cubic boron nitride, and a Vickers hardness of 20 GPa, which is close to sapphire. Theoretical calculations for NbN show that all elastic moduli increase monotonically with increasing pressure. These results suggest technological applications of such materials in extreme environments. PMID:15728352

Chen, Xiao-Jia; Struzhkin, Viktor V; Wu, Zhigang; Somayazulu, Maddury; Qian, Jiang; Kung, Simon; Christensen, Axel Nørlund; Zhao, Yusheng; Cohen, Ronald E; Mao, Ho-kwang; Hemley, Russell J

2005-02-22

53

Comparison of Quality Characteristics and Breadmaking Functionality of Hard Red Winter and Hard Red Spring Wheat  

Microsoft Academic Search

Cereal Chem. 83(5):520-528 Various whole-kernel, milling, flour, dough, and breadmaking quality parameters were compared between hard red winter (HRW) and hard red spring (HRS) wheat. From the 50 quality parameters evaluated, values of only nine quality characteristics were found to be similar for both classes. These were test weight, grain moisture content, kernel size, polyphenol oxidase content, average gluten index,

E. B. Maghirang; G. L. Lookhart; S. R. Bean; R. O. Pierce; F. Xie; M. S. Caley; J. D. Wilson; B. W. Seabourn; M. S. Ram; S. H. Park; O. K. Chung; F. E. Dowell

2006-01-01

54

THEORY OF FLUX CREEP IN HARD SUPERCONDUCTORS  

Microsoft Academic Search

Previous investigations of the critical state of the hard superconductor ; have defined it in terms of constants alpha and B\\/sub O\\/; alpha (T) = J\\/sub cr\\/; (B\\/sub cr\\/ + Bâ). If the current density J or the field B is increased ; beyond the critical values, a process called flux creep'' sets in, and flux ; leaks through the

P. Anderson

1962-01-01

55

Hard Constrained Semi-Markov Decision Processes  

Microsoft Academic Search

In multiple criteria Markov Decision Processes (MDP) where multiple costs are incurred at every decision point, current methods solve them by minimising the expected primary cost criterion while constraining the expectations of other cost criteria to some critical values. However, systems are of- ten faced with hard constraints where the cost criteria should never exceed some criticalvalues at any time,

Wai-leong Yeow; Chen-khong Tham; Wai-choong Wong

2006-01-01

56

Diffractive hard scattering  

SciTech Connect

I discuss events in high energy hadron collisions that contain a hard scattering, in the sense that very heavy quarks or high P/sub T/ jets are produced, yet are diffractive, in the sense that one of the incident hadrons is scattered with only a small energy loss. 8 refs.

Berger, E.L.; Collins, J.C.; Soper, D.E.; Sterman, G.

1986-03-01

57

CSI: Hard Drive  

ERIC Educational Resources Information Center

|Acting on information from students who reported seeing a classmate looking at inappropriate material on a school computer, school officials used forensics software to plunge the depths of the PC's hard drive, searching for evidence of improper activity. Images were found in a deleted Internet Explorer cache as well as deleted file space.…

Sturgeon, Julie

2008-01-01

58

Budgeting in Hard Times.  

ERIC Educational Resources Information Center

|Interviews with school board members and administrators produced a list of suggestions for balancing a budget in hard times. Among these are changing calendars and schedules to reduce heating and cooling costs; sharing personnel; rescheduling some extracurricular activities; and forming cooperative agreements with other districts. (MLF)|

Parrino, Frank M.

2003-01-01

59

Work Hard. Be Nice  

ERIC Educational Resources Information Center

|In 1994, fresh from a two-year stint with Teach for America, Mike Feinberg and Dave Levin inaugurated the Knowledge Is Power Program (KIPP) in Houston with an enrollment of 49 5th graders. By this Fall, 75 KIPP schools will be up and running, setting children from poor and minority families on a path to college through a combination of hard work,…

Mathews, Jay

2009-01-01

60

Running in Hard Times  

ERIC Educational Resources Information Center

|Roberta Stevens and Kent Oliver are campaigning hard for the presidency of the American Library Association (ALA). Stevens is outreach projects and partnerships officer at the Library of Congress. Oliver is executive director of the Stark County District Library in Canton, Ohio. They have debated, discussed, and posted web sites, Facebook pages,…

Berry, John N., III

2009-01-01

61

LONG-TERM STABILITY OF RUBBER HARDNESS REFERENCE BLOCKS  

Microsoft Academic Search

Methods for hardness measurement on elastomers are characterized by a set-up where indenters with various defined geometries are pressed under defined test forces into the surface of testing material. The hardness value represents the resistance of the material to the rigid indenter and is calculated from the indentation depth of the indenter in the to be tested material. The test

Konrad Herrmann

2004-01-01

62

Comparison of Ultrasonic-Hardness-Tester Hardness and Micro-Vickers Hardness  

NASA Astrophysics Data System (ADS)

Examination methods of industrial hardnesses such as Vickers hardness and Rockwell hardness are used for the characteristic measurement of materials. These methods assume that the length of the plastic deformation is a reliable index of hardness. Since the indenters used in these methods produce deformation imprints and the methods themselves are difficult to perform, they cannot be used for the ready measurement of hardness. Recently, a nondestructive ultrasonic hardness tester that is capable of measuring the hardness of materials has been developed by the authors. This tester can measure small areas rapidly and accurately. Another advantage of this tester is that it can measure a wide range of hardness. Therefore, we consider that it is highly advantageous to replace conventional hardness testers with ultrasonic hardness testers. In this study, ultrasonic hardness was compared with micro-Vickers hardness. As a result, it was clarified that micro-Vickers hardness was in proportion to the 4.25th power of the index of ultrasonic hardness.

Aoyagi, Ryoji; Umezu, Kaoru

2007-07-01

63

Water hardness and sodium trends in Texas aquifers.  

PubMed

Median hardness and sodium levels in groundwater were calculated for 244 Texas counties from measurements at 7728 water wells. The data were mapped and analyzed with a geographic information system (GIS). County median hardness levels varied widely, from 4-2304 mg L-1. More than 60% of the counties had hardness medians above 180 mg L-1. County medium sodium concentrations ranged from 6-1170 mg L-1, with more than 90% of those values exceeding 20 mg L-1. There was a significant positive correlation between hardness and sodium concentrations in six of Texas' nine major aquifers. A significant negative correlation between hardness and sodium was observed in two aquifers. Several factors control hardness and sodium variations in Texas aquifers including rock/sediment composition, groundwater chemical evolution, and seepage from nearby formations. Probable human controls include agricultural return flow and pumping-induced saltwater intrusion. PMID:11411143

Hudak, P F

2001-05-01

64

Hard surface detergency  

Microsoft Academic Search

In a study of hard surface detergency using glyceryl trioleate, oleic acid, and octanoic acid soils with three types of anionic\\u000a and three types of nonionic syndets, only potassium laurate showed maximum detergency at the CMC (critical micelle concentration),\\u000a with the potassium laurateoctanoic acid system being an exception. In general glyceryl trioleate and oleic soil removal (180°F.)\\u000a at the CMC

A. M. Mankowich

1961-01-01

65

Eat Smart. Play Hard.  

NSDL National Science Digital Library

The Food and Nutrition Service of the US Department of Agriculture offers online educational material as part of "Eat Smart. Play Hard." -- a public information campaign designed to promote healthy living in American children. While the site and its materials are geared for use by state and local program coordinators, anyone is welcome to download the available information and activity sheets. Click on Cool Stuff for Kids for nutrition-related puzzles and games. Parents Place offers informational brochures and an educational bookmark.

66

Voronoi neighbor statistics of hard-disks and hard-spheres  

NASA Astrophysics Data System (ADS)

The neighbor distribution in hard-sphere and hard-disk fluids is analyzed using Voronoi tessellation. The statistical measures analyzed are the nth neighbor coordination number (Cn), the nth neighbor distance distribution [fn(r)], and the distribution of the number of Voronoi faces (Pn). These statistics are sensitive indicators of microstructure, and they distinguish thermodynamic and annealed structures. A sharp rise in the hexagon population marks the onset of hard-disk freezing transition, and Cn decreases sharply to the hexagonal lattice values. In hard-disk random structures the pentagon and heptagon populations remain significant even at high volume fraction. In dense hard-sphere (three-dimensional) structures at the freezing transition, C1 is close to 14, instead of the value of 12 expected for a face-centered-cubic lattice. This is found to be because of a topological instability, where a slight perturbation of the positions in the centers of a pair of particles transforms a vertex in the Voronoi polyhedron into a Voronoi surface. We demonstrate that the pair distribution function and the equation-of-state obtained from Voronoi tessellation are equal to those obtained from thermodynamic calculations. In hard-sphere random structures, the dodecahedron population decreases with increasing density. To demonstrate the utility of the neighbor analysis, we estimate the effective hard-sphere diameter of the Lennard-Jones fluid by identifying the diameter of the spheres in the hard-sphere fluid which has C1 equal to that for the Lennard-Jones fluid. The estimates are within 2% deviation from the theoretical results of Barker-Henderson and Weeks-Chandler-Andersen.

Kumar, V. Senthil; Kumaran, V.

2005-08-01

67

Hard-pan soils - Management  

Technology Transfer Automated Retrieval System (TEKTRAN)

Hard pans, hard layers, or compacted horizons, either surface or subsurface, are universal problems that limit crop production. Hard layers can be caused by traffic or soil genetic properties that result in horizons with high density or cemented soil particles; these horizons have elevated penetrati...

68

Measurement of dynamic hardness by controlled sharp-projectile impact  

SciTech Connect

Impact of ZnS by a pyramidal projectile was used to provide a measurement of the dynamic hardness and to obtain direct comparison of the contact damage produced by static loading and impact. The dynamic hardness was evaluated from measurements of residual contact dimensions as a function of impact velocity over the velocity range 5 to 40 m X s/sup -1/. The value obtained (H /SUB d/ =5.0 GPa) was higher than the static hardness (H /SUB s/ =1.9 GPa). The higher hardness in impact causes more extensive cracking, an increase in the elastic recovery of the depth of the residual contact impression, and a smaller plastic zone surrounding the contact site. The relative extents of cracking in impact and static loading are predicted by a quasistatic indentation fracture mechanics analysis along with the appropriate values of hardness.

Marshall, D.B.; Evans, A.G.; Nisenholz, H.

1983-08-01

69

Values and Moral Values  

Microsoft Academic Search

\\u000a The vertical table of values and disvalues according to their relative worth that was presented in Chap. 2 as part of Scheler’s\\u000a phenomenology of cognitive acts of feeling and preference is now developed by Hartmann in several dimensions. He (1) distinguishes\\u000a moral values and non-moral values; (2) studies how some of the latter’s contents causally condition the content of the

Eugene Kelly

70

Hard diffraction in CDF  

SciTech Connect

The aim of these studies is to use hard (large Q{sup 2}) processes to investigate the partonic nature of the pomeron. We have measured events with large rapidity gaps between balancing high E{sub T} jets, events with two forward (same-side) jets and a large gap (diffractive di-jet production), diffractive W{sup {+-}} production and diffractive heavy flavor (J/{psi} and b-quark) production. Candidate events of the type double-pomeron {yields} di-jet are observed. I close with a look at the future (Run II).

Albrow, M.G.; CDF Collaboration

1997-10-01

71

Hard metal composition  

DOEpatents

A composition of matter having a Rockwell A hardness of at least 85 is formed from a precursor mixture comprising between 3 and 10 weight percent boron carbide and the remainder a metal mixture comprising from 70 to 90 percent tungsten or molybdenum, with the remainder of the metal mixture comprising nickel and iron or a mixture thereof. The composition has a relatively low density of between 7 to 14 g/cc. The precursor is preferably hot pressed to yield a composition having greater than 100% of theoretical density.

Sheinberg, Haskell (Los Alamos, NM)

1986-01-01

72

Hard Metal Disease  

PubMed Central

In Great Britain there have been no published reports of respiratory disease occurring amongst workers in the hard metal (tungsten carbide) industry. In this paper the clinical and radiological findings in six cases and the pathological findings in one are described. In two cases physiological studies indicated mild alveolar diffusion defects. Histological examination in a fatal case revealed diffuse pulmonary interstitial fibrosis with marked peribronchial and perivascular fibrosis and bronchial epithelial hyperplasia and metaplasia. Radiological surveys revealed the sporadic occurrence and low incidence of the disease. The alterations in respiratory mechanics which occurred in two workers following a day's exposure to dust are described. Airborne dust concentrations are given. The industrial process is outlined and the literature is reviewed. The toxicity of the metals is discussed, and our findings are compared with those reported from Europe and the United States. We are of the opinion that the changes which we would describe as hard metal disease are caused by the inhalation of dust at work and that the component responsible may be cobalt. Images

Bech, A. O.; Kipling, M. D.; Heather, J. C.

1962-01-01

73

Regularized 13 moment equations for hard spheres  

NASA Astrophysics Data System (ADS)

The regularized 13 moment equations (R13) of rarefied gas dynamics for a monatomic hard sphere gas in the linear regime are presented. The equations are based on an extended Grad-type moment system, which was systematically reduced by means of the Order of Magnitude Method [Struchtrup, Phys. Fluids 16(11), 3921-3934 (2004)]. The linear Burnett and super-Burnett equations are derived from Chapman-Enskog expansion of the R13 equations. While the Burnett coefficients agree with literature values, this seems to be the first time that super-Burnett coefficients are computed for a hard sphere gas. The equations are considered for stability, and dispersion and damping of sound waves. Boundary conditions are given, and solutions of simple boundary value problems are briefly discussed.

Struchtrup, Henning; Torrilhon, Manuel

2012-11-01

74

The k-Anonymity Problem Is Hard  

NASA Astrophysics Data System (ADS)

The problem of publishing personal data without giving up privacy is becoming increasingly important. An interesting formalization recently proposed is the k-anonymity. This approach requires that the rows in a table are clustered in sets of size at least k and that all the rows in a cluster are related to the same tuple, after the suppression of some records. The problem has been shown to be NP-hard when the values are over a ternary alphabet, k = 3 and the rows length is unbounded. In this paper we give a lower bound on the approximation of two restrictions of the problem, when the records values are over a binary alphabet and k = 3, and when the records have length at most 8 and k = 4, showing that these restrictions of the problem are APX-hard.

Bonizzoni, Paola; Della Vedova, Gianluca; Dondi, Riccardo

75

[Hard metal interstitial lung disease].  

PubMed

Hard metal lung disease is an unusual disease which can occur in individuals exposed to hard metals. Clinically, the condition resembles hypersensitivity pneumonitis depending mainly on individual susceptibility, which eventually progresses to pulmonary fibrosis. We present two patients with pulmonary fibrosis, who were actually diagnosed after an exhaustive anamnesis and examination of the tissue by scanning microscope to discard hard metals. The evaluation of wedge biopsies by scanning electronic microscope can be very helpful in those cases without a specific diagnosis. PMID:19962814

Montero, M Angeles; de Gracia, Javier; Morell, Ferràn

2009-12-04

76

Diffusion welding of hard alloys  

Microsoft Academic Search

1.The hot pressing method, which is characterized by induction heating in graphite dies, can be used for the diffusion welding of tungsten-cobalt hard alloys and the “baking-on” of new hard-alloy layers consisting of hard-alloy powder mixtures.2.Mechanical tests have shown that the strength secured by means of diffusion welding at 1400° according to the proposed method approaches the strength of the

K. S. Gerasimenko; S. I. Spirina

1967-01-01

77

Microstructure, Composition, and Hardness of Rockwell C Hardness Blocks.  

National Technical Information Service (NTIS)

The microstructure, composition, and hardness of hardness blocks (Rockwell C scale) that are commonly available in the country were examined. Blocks near HRC levels of 25, 45, and 65 were obtained from each of six sources to represent the HRC measurement ...

T. A. Siewert A. Tomer

1991-01-01

78

Measuring the Hardness of Minerals  

ERIC Educational Resources Information Center

|The author discusses Moh's hardness scale, a comparative scale for minerals, whereby the softest mineral (talc) is placed at 1 and the hardest mineral (diamond) is placed at 10, with all other minerals ordered in between, according to their hardness. Development history of the scale is outlined, as well as a description of how the scale is used…

Bushby, Jessica

2005-01-01

79

Nonconventional Hard-Metal Compositions.  

National Technical Information Service (NTIS)

A novel hard-metal composition comprising borides and carbides of tungsten, nickel, and iron is made by reaction hot-pressing mixtures of elemental tungsten, nickel, and iron powders with small quantities of boron carbide. The hardness of these compositio...

H. Sheinberg

1982-01-01

80

Hard Disk Drive Manufacturing Optimization  

Microsoft Academic Search

Rapid increase in demand for high hard disk data storage density is forcing R&D centers and manufacturing companies to focus on continuous improvement of hard disk drive (HDD) performance. Current HDD records data on the magnetic disk or platter by controlling a magnetizing ferromagnetic material directionally. The data are read from the disk using a magnetic head by detecting the

Riadh Zaier; Jamil Abdo

2012-01-01

81

Hardness and durability of ring plate valves of piston compressors  

Microsoft Academic Search

At the Moscow Coke and Gas Plant an air compressor has been used to investigate fractured plates of type 30KhGSA steel with HRC hardness values of 32-51. A Rockwell instrument was used to measure the hardness of each fractured plate (10 impressions each side) and each plate was checked by a magnetic luminscence method on a type LD-4 instrument to

V. V. Afonskaya; K. S. Moskvitin; L. Ya. Plshchik; B. A. Gor'kov

1982-01-01

82

Absolute electronegativity and hardness: application to inorganic chemistry  

Microsoft Academic Search

The recent concepts of absolute electronegativity, \\/chi\\/, and absolute hardness, \\/eta\\/, are briefly reviewed. The operational definitions, \\/chi\\/ = (I + A)\\/2 and \\/eta\\/ = (I - A)\\/2, are used to calculate experimental values for a large number of cations, atoms, radicals, and molecules. The resulting values are shown to be in good agreement with chemical behavior, both as to

Ralph G. Pearson

1988-01-01

83

Eikonal Corrections to Hard Processes.  

National Technical Information Service (NTIS)

We consider within Quantum Chromodynamics those semi-inclusive hard processes where two large mass scales appear. Summation of single and double logarithms arising from soft gluonic emission introduces eikonal form factors. We obtain a satisfactory agreem...

G. Bordes A. Nicolaidis

1981-01-01

84

Melting of polydisperse hard disks  

NASA Astrophysics Data System (ADS)

The melting of a polydisperse hard-disk system is investigated by Monte Carlo simulations in the semigrand canonical ensemble. This is done in the context of possible continuous melting by a dislocation-unbinding mechanism, as an extension of the two-dimensional hard-disk melting problem. We find that while there is pronounced fractionation in polydispersity, the apparent density-polydispersity gap does not increase in width, contrary to 3D polydisperse hard spheres. The point where the Young’s modulus is low enough for the dislocation unbinding to occur moves with the apparent melting point, but stays within the density gap, just like for the monodisperse hard-disk system. Additionally, we find that throughout the accessible polydispersity range, the bound dislocation-pair concentration is high enough to affect the dislocation-unbinding melting as predicted by Kosterlitz, Thouless, Halperin, Nelson, and Young.

Pronk, Sander; Frenkel, Daan

2004-06-01

85

Water Hardness and Cardiovascular Disease.  

National Technical Information Service (NTIS)

A brief review of the present state of knowledge regarding the relationship of water hardness to cardiovascular disease. Also included are recommendations for future research and a statement on the appropriateness of modifying current water treatment prac...

1979-01-01

86

Elastic recovery at hardness indentations  

Microsoft Academic Search

The mechanics of hardness indentation are considered. On the basis of a cycle in which the loading is elastic-plastic and the unloading (and subsequent reloading) elastic, an expression is derived for the relative depth recovery of the impression as a function of hardness\\/modulus,H\\/E. Experimental observations on indented surfaces of selected materials, mostly ceramics, using a tilting procedure in the scanning

B. R. Lawn; V. R. Howes

1981-01-01

87

Einstein Hardness Ratios from a User-Developed IRAF Script  

NASA Astrophysics Data System (ADS)

Here we describe how IRAF/PROS was used to compute source hardness ratios for the recently published Einstein Catalog of IPC X-ray Sources. This catalog was prepared from the Imaging Proportional Counter (IPC) data of the Einstein X-ray Observatory, which operated in low-earth orbit from 1978 Nov until 1981 May. Before the catalog went to press, it was discovered that a bug in the production processing system had rendered the hardness ratios unreliable. For this reason, it was necessary to generate corrected hardness ratios for inclusion in the catalog. Our corrected hardness ratios were generated for ~4000 tabulated sources using the PI-corrected "qpoe" files from the IPC event list CDROMs. An IRAF script was written which, given a list of sources, performs spectral extraction and computes the source and background count values needed for the hardness ratio calculation. These values were used as input for a previously-developed maximum likelihood algorithm to compute hardness ratios and errors for the sources. Using existing IRAF commands and tasks, we were able to process a large amount of the data quickly and conveniently. For tasks such as detailed data formatting and file manipulation, however, it was convenient to invoke AWK and Unix scripts. This underscores the desirability of having heterogeneous analysis tools even more readily available to scientific users in a unified software environment.

Rhode, K. L.; Harnden, F. R., Jr.

88

30 CFR 77.1710-1 - Distinctively colored hard hats or hard caps; identification for newly employed, inexperienced...  

Code of Federal Regulations, 2013 CFR

...Distinctively colored hard hats or hard caps; identification for newly employed, inexperienced...Distinctively colored hard hats or hard caps; identification for newly employed, inexperienced miners. Hard hats or hard caps distinctively different in color...

2013-07-01

89

30 CFR 75.1720-1 - Distinctively colored hard hats, or hard caps; identification for newly employed, inexperienced...  

Code of Federal Regulations, 2013 CFR

...Distinctively colored hard hats, or hard caps; identification for newly employed, inexperienced...Distinctively colored hard hats, or hard caps; identification for newly employed, inexperienced miners. Hard hats or hard caps distinctively different in color...

2013-07-01

90

The phase behavior of linear and partially flexible hard-sphere chain fluids and the solubility of hard spheres in hard-sphere chain fluids  

NASA Astrophysics Data System (ADS)

The liquid crystal phase behavior of linear and partially flexible hard-sphere chain fluids and the solubility of hard spheres in hard-sphere chain fluids are studied by constant pressure Monte Carlo simulations. An extensive study on the phase behavior of linear fluids with a length of 7, 8, 9, 10, 11, 12, 13, 14, 15, and 20 beads is carried out. The phase behavior of partially flexible fluids with a total length of 8, 10, 14, and 15 beads and with different lengths for the linear part is also determined. A precise description of the reduced pressure and of the packing fraction change at the isotropic-nematic coexistence was achieved by performing long simulation runs. For linear fluids, a maximum in the isotropic to nematic packing fraction change is observed for a chain length of 15 beads. The infinite dilution solubility of hard spheres in linear and partially flexible hard-sphere chain fluids is calculated by the Widom test-particle insertion method. To identify the effect of chain connectivity and molecular anisotropy on free volume, solubility is expressed relative to that of hard spheres in a hard sphere fluid at same packing fraction as relative Henry's law constants. A linear relationship between relative Henry's law constants and packing fraction is observed for all linear fluids. Furthermore, this linearity is independent of liquid crystal ordering and seems to be independent of chain length for linear chains of 10 beads and longer. The same linear relationship was observed for the solubility of hard spheres in nematic forming partially flexible fluids for packing fractions up to a value slightly higher than the nematic packing fraction at the isotropic-nematic coexistence. At higher packing fractions, the small flexibility of these fluids seems to improve solubility in comparison with the linear fluids.

Oyarzún, Bernardo; van Westen, Thijs; Vlugt, Thijs J. H.

2013-05-01

91

The phase behavior of linear and partially flexible hard-sphere chain fluids and the solubility of hard spheres in hard-sphere chain fluids.  

PubMed

The liquid crystal phase behavior of linear and partially flexible hard-sphere chain fluids and the solubility of hard spheres in hard-sphere chain fluids are studied by constant pressure Monte Carlo simulations. An extensive study on the phase behavior of linear fluids with a length of 7, 8, 9, 10, 11, 12, 13, 14, 15, and 20 beads is carried out. The phase behavior of partially flexible fluids with a total length of 8, 10, 14, and 15 beads and with different lengths for the linear part is also determined. A precise description of the reduced pressure and of the packing fraction change at the isotropic-nematic coexistence was achieved by performing long simulation runs. For linear fluids, a maximum in the isotropic to nematic packing fraction change is observed for a chain length of 15 beads. The infinite dilution solubility of hard spheres in linear and partially flexible hard-sphere chain fluids is calculated by the Widom test-particle insertion method. To identify the effect of chain connectivity and molecular anisotropy on free volume, solubility is expressed relative to that of hard spheres in a hard sphere fluid at same packing fraction as relative Henry's law constants. A linear relationship between relative Henry's law constants and packing fraction is observed for all linear fluids. Furthermore, this linearity is independent of liquid crystal ordering and seems to be independent of chain length for linear chains of 10 beads and longer. The same linear relationship was observed for the solubility of hard spheres in nematic forming partially flexible fluids for packing fractions up to a value slightly higher than the nematic packing fraction at the isotropic-nematic coexistence. At higher packing fractions, the small flexibility of these fluids seems to improve solubility in comparison with the linear fluids. PMID:23742514

Oyarzún, Bernardo; van Westen, Thijs; Vlugt, Thijs J H

2013-05-28

92

Hope in Hard Times  

PubMed Central

In the face of challenging times, advocates for women and their families in maternal-child health care continue to promote evidence-based and mother-/baby-friendly care. What qualities allow childbirth educators, doulas, nurses, and perinatal care providers to keep going even when the health-care practices around them often do not match their values? This editorial explores the impact of recent trends in which increasing utilization of elective technology in maternity care may affect the individual commitment of childbirth advocates. Borrowing from research on successful advocates in other fields, the author speculates on both why and how childbirth advocates sustain commitment and how “we will prevail.”

Leslie, Mayri Sagady

2008-01-01

93

Place Value  

NSDL National Science Digital Library

Practice place value! Fight the pirates in Pirates Place Value Uncover the hidden picture in Place value hidden picture Take the quiz at place value quiz Keep practicing with Place value to 1000 Stretch your brain with Place value to 100,000 ...

Peake, Mrs.

2011-08-18

94

The hard truth  

SciTech Connect

In the Bayesian methodology, the posterior probability combines uncertainty about prior knowledge, and available data about alternative models of reality. The posterior quantifies the degree of certainty one has in inferring the truth in terms of those models. We propose a method to determine the reliability of a specific feature of a Bayesian solution. Our approach is based on an analogy between the negative logarithm of the posterior and a physical potential. This analogy leads to the interpretation of gradient of this potential as a force that acts on the model. As model parameters are perturbed from their maximum a posteriori (MAP) values, the strength of the restoring force that drives them back to the MAP solution is directly related to the reliability of those parameter estimates. The correlations between the uncertainties of parameter estimates can be elucidated.

Hanson, K.M.; Cunningham, C.S.

1994-12-31

95

Correlation of Yield Strength and Tensile Strength with Hardness for Steels  

NASA Astrophysics Data System (ADS)

Hardness values as well as yield and tensile strength values were compiled for over 150 nonaustenitic, hypoeutectoid steels having a wide range of compositions and a variety of microstructures. The microstructures include ferrite, pearlite, martensite, bainite, and complex multiphase structures. The yield strength of the steels ranged from approximately 300 MPa to over 1700 MPa. Tensile strength varied over the range of 450-2350 MPa. Regression analysis was used to determine the correlation of the yield strength and the tensile strength to the diamond pyramid hardness values for these steels. Both the yield strength and tensile strength of the steels exhibited a linear correlation with the hardness over the entire range of strength values. Empirical relationships are provided that enable the estimation of strength from a bulk hardness measurement. A weak effect of strain-hardening potential on the hardness-yield strength relationship was also observed.

Pavlina, E. J.; van Tyne, C. J.

2008-12-01

96

Indentation hardness evaluation of cathodic arc deposited thin hard coatings  

Microsoft Academic Search

One trend in the development of wear-resistant vapour deposited coatings is to make them increasingly harder and thinner, by improvement and optimisation of the deposition processes. A complex interdependence exists between the individual properties of a coating and a substrate on the one hand, and those of the ‘composite’ coated system on the other. For example, system stiffness and hardness

J. R. Tuck; A. M. Korsunsky; D. G. Bhat; S. J. Bulla

2001-01-01

97

Magnetic levitation for hard superconductors  

SciTech Connect

An approach for calculating the interaction between a hard superconductor and a permanent magnet in the field-cooled case is proposed. The exact solutions were obtained for the point magnetic dipole over a flat ideally hard superconductor. We have shown that such an approach is adaptable to a wide practical range of melt-textured high-temperature superconductors{close_quote} systems with magnetic levitation. In this case, the energy losses can be calculated from the alternating magnetic field distribution on the superconducting sample surface. {copyright} {ital 1998 American Institute of Physics.}

Kordyuk, A.A. [Institute of Metal Physics, 252680 Kiev 142 (Ukraine)

1998-01-01

98

Future hard disk drive systems  

NASA Astrophysics Data System (ADS)

This paper briefly reviews the evolution of today's hard disk drive with the additional intention of orienting the reader to the overall mechanical and electrical architecture. The modern hard disk drive is a miracle of storage capacity and function together with remarkable economy of design. This paper presents a personal view of future customer requirements and the anticipated design evolution of the components. There are critical decisions and great challenges ahead for the key technologies of heads, media, head-disk interface, mechanics, and electronics.

Wood, Roger

2009-03-01

99

On the validity of the maximum hardness principle and the minimum electrophilicity principle during chemical reactions.  

PubMed

Hardness and electrophilicity values for several molecules involved in different chemical reactions are calculated at various levels of theory and by using different basis sets. Effects of these aspects as well as different approximations to the calculation of those values vis-à-vis the validity of the maximum hardness and minimum electrophilicity principles are analyzed in the cases of some representative reactions. Among 101 studied exothermic reactions, 61.4% and 69.3% of the reactions are found to obey the maximum hardness and minimum electrophilicity principles, respectively, when hardness of products and reactants is expressed in terms of their geometric means. However, when we use arithmetic mean, the percentage reduces to some extent. When we express the hardness in terms of scaled hardness, the percentage obeying maximum hardness principle improves. We have observed that maximum hardness principle is more likely to fail in the cases of very hard species like F(-), H(2), CH(4), N(2), and OH appearing in the reactant side and in most cases of the association reactions. Most of the association reactions obey the minimum electrophilicity principle nicely. The best results (69.3%) for the maximum hardness and minimum electrophilicity principles reject the 50% null hypothesis at the 2% level of significance. PMID:23373511

Pan, Sudip; Solà, Miquel; Chattaraj, Pratim K

2013-02-15

100

Hard Disk Integrity Check by Hashing with Combinatorial Group Testing  

Microsoft Academic Search

In this paper, we describe the problem of verifying the integrity of a hard disk especially for forensics investigation after the computer of a suspect has been seized. Existing solutions do not provide a satisfactory solution to solve the problem. They either require a huge amount of storage to store the hash values of the sectors or may not be

Junbin Fang; Zoe L. Jiang; S. M. Yiu; Lucas C. K. Hui

2009-01-01

101

Hardness and shock absorption of silicone rubber for mouth guards  

Microsoft Academic Search

Silicone rubbers have general properties that make them suitable for the fabrication of custom-made mouth guards. This study evaluated the shock absorption properties and Shore A hardness of several silicone rubbers and derived products, compared their values with those of materials commonly used for the manufacture of mouth guards, and correlated the shock absorption and transmission abilities of these different

Pascal Auroy; Philippe Duchatelard; Nour E Zmantar; Martine Hennequin

1996-01-01

102

Processed Apple Product Marketing Analysis: Hard Cider and Apple Wine  

Microsoft Academic Search

Hard cider and apple wine offer new value-added marketing opportunities to the apple industry. Both products are situated in rapidly growing categories of the beverage industry. The development of effective marketing strategies for these products requires an understanding of the forces driving competition in these markets. This paper provides background information to support competitive analysis and strategy development. Development of

Kristin Rowles

2000-01-01

103

Nanoindentation of wood cell walls: Continuous stiffness and hardness measurements  

Microsoft Academic Search

The objective of this study was to measure the mechanical properties of individual, native wood fibers using the continuous nanoindentation measurement technique. The indentation depth profile exhibited a small length-scale effect, which was confirmed using the size-effect index derived from the indentation loading curve. The hardness (Hu) or stiffness (Eu) values determined from indentation unloading were also examined for 10

W. T. Y. Tze; S. Wang; T. G. Rials; G. M. Pharr; S. S. Kelley

2007-01-01

104

Place Value  

NSDL National Science Digital Library

These activites cover place value of ones, tens, hundreds and thousands. Please complete the games in order. You must finish each game before going on to the next one. Game #1: Dinosaur Numbers (place value) Game #2: Shark Numbers (place value) Game #3: Place Value Golf (harder) ...

Christian, Mrs.

2007-03-21

105

A hard case for modeling  

Microsoft Academic Search

What happens to a human head when it is hit in an accident or by a weapon, or subjected to the violence of an emergency ejection from a combat plane? This question is something that interests QinetiQ, part of the former UK Defence Evaluation and Research Agency (DERA). Controlled experimentation on live subjects is hardly an option, but computer modeling

George Marsh

2002-01-01

106

Hard Probes 2012: Experimental Summary  

NASA Astrophysics Data System (ADS)

The 5thinternational Conference on Hard and Electromagnetic Probes in High-Energy Nuclear Collisions was held in May 2012 in Cagliari, Italy. This contribution summarises some of the experimental highlights presented at the meeting, concentrating on new results from LHC and RHIC on parton energy loss ('jet-quenching') and heavy quark meson production ('quarkonia suppression').

Schukraft, J.

2013-08-01

107

Hard scattering in ?p interactions  

NASA Astrophysics Data System (ADS)

We report on the investigation of the final state in interactions of quasi-real photons with protons. The data were taken with the H1 detector at the HERA ep collider. Evidence for hard interactions is seen in both single particle spectra and jet formation. The data can best be described by inclusion of resolved photon processess as predicted by QCD.

Ahmed, T.; Andreev, V.; Andrieu, B.; Arpagaus, M.; Babayev, A.; Bärwolff, H.; Ban, J.; Baranov, P.; Barrelet, E.; Bartel, W.; Bassler, U.; Beck, G. A.; Beck, H. P.; Behrend, H.-J.; Belousov, A.; Berger, Ch.; Bergstein, H.; Bernardi, G.; Bernet, R.; Berthon, U.; Bertrand-Coremans, G.; Besancon, M.; Biddulph, P.; Binder, E.; Bizot, J. C.; Blobel, V.; Borras, K.; Bosetti, P. C.; Boudry, V.; Bourdarios, C.; Brasse, F.; Braun, U.; Braunschweig, W.; Brisson, V.; Bruncko, D.; Bürger, J.; Büsser, F. W.; Buniatian, A.; Burke, S.; Buschhorn, G.; Campbell, A. J.; Carli, T.; Charles, F.; Clarke, D.; Clegg, A. B.; Colombo, M.; Coughlan, J. A.; Courau, A.; Coutures, C.; Cozzika, G.; Criegee, L.; Cvach, J.; Dainton, J. B.; Danilov, M.; Dann, A. W. E.; Dau, W. D.; David, M.; Deffur, E.; Delcourt, B.; Delbuono, L.; Devel, M.; Deroeck, A.; Dingus, P.; Dollfus, C.; Dowell, J. D.; Dreis, H. B.; Drescher, A.; Duboc, J.; Düllmann, D.; Dünger, O.; Duhm, H.; Eberle, M.; Ebert, J.; Ebert, T. R.; Eckerlin, G.; Efremenko, V.; Egli, S.; Eichenberger, S.; Eichler, R.; Eisele, F.; Eisenhandler, E.; Ellis, N. N.; Ellison, R. J.; Elsen, E.; Erdmann, M.; Evrard, E.; Favart, L.; Fedotov, A.; Feeken, D.; Felst, R.; Feltesse, J.; Feng, Y.; Fensome, I. F.; Ference, J.; Ferrarotto, F.; Flauger, W.; Fleischer, M.; Flügge, G.; Fomenko, A.; Fominykh, B.; Forbush, M.; Formanek, J.; Foster, J. M.; Franke, G.; Fretwurst, E.; Fuhrmann, P.; Gabathuler, E.; Gamerdinger, K.; Garvey, J.; Gayler, J.; Gellrich, A.; Gennis, M.; Gensch, U.; Genzel, H.; Gerhards, R.; Gillespie, D.; Godfrey, L.; Goerlach, U.; Goerlich, L.; Goldberg, M.; Goodall, A. M.; Gorelov, I.; Goritchev, P.; Grab, C.; Grässler, H.; Grässler, R.; Greenshaw, T.; Greif, H.; Grindhammer, G.; Gruber, C.; Haack, J.; Haidt, D.; Hajduk, L.; Hamon, O.; Handschuh, D.; Hanlon, E. M.; Hapke, M.; Harjes, J.; Hartz, P.; Haydar, R.; Haynes, W. J.; Heatherington, J.; Hedberg, V.; Hedgecock, R.; Heinzelmann, G.; Henderson, R. C. W.; Henschel, H.; Herma, R.; Herynek, I.; Hildesheim, W.; Hill, P.; Hilton, C. D.; Hladky, J.; Hoeger, K. C.; Huet, Ph.; Hufnagel, H.; Huot, N.; Ibbotson, M.; Jabiol, M. A.; Jacholkowska, A.; Jacobson, C.; Jaffre, M.; Jönsson, L.; Johannsen, K.; Johnson, D.; Johnson, L.; Jung, H.; Kalmus, P. I. P.; Kasarian, S.; Kaschowitz, R.; Kasselmann, P.; Kathage, U.; Kaufmann, H. H.; Kenyon, I. R.; Kermiche, S.; Kiesling, C.; Klein, M.; Kleinwort, C.; Knies, G.; Köhler, T.; Kolanoski, H.; Kole, F.; Kolya, S. D.; Korbel, V.; Korn, M.; Kostka, P.; Kotelnikov, S. K.; Krasny, M. W.; Krehbiel, H.; Krücker, D.; Krüger, U.; Kubenka, J. P.; Küster, H.; Kuhlen, M.; Kurca, T.; Kurzhöfer, J.; Kuznik, B.; Lander, R.; Landon, M. P. J.; Langkau, R.; Lanius, P.; Laporte, J. F.; Lebedev, A.; Lenhardt, U.; Leuschner, A.; Leverenz, C.; Levin, D.; Levonian, S.; Ley, Ch.; Lindström, G.; Loch, P.; Lohmander, H.; Lopez, G. C.; Lüers, D.; Magnussen, N.; Malinovski, E.; Mani, S.; Marage, P.; Marks, J.; Marshall, R.; Martens, J.; Martin, R.; Martyn, H.-U.; Martyniak, J.; Masson, S.; Mavroidis, A.; Maxfield, S. J.; McMahon, S. J.; Mehta, A.; Meier, K.; Merz, T.; Meyer, C. A.; Meyer, H.; Meyer, J.; Mikocki, S.; Milone, V.; Monnier, E.; Moreau, F.; Moreels, J.; Morris, J. V.; Morton, J. M.; Müller, K.; Murin, P.; Murray, S. A.; Nagovizin, V.; Naroska, B.; Naumann, Th.; Newton, D.; Nguyen, H. K.; Niebergall, F.; Nisius, R.; Nowak, G.; Noyes, G. W.; Nyberg, M.; Oberlack, H.; Obrock, U.; Olsson, J. E.; Orenstein, S.; Ould-Saada, F.; Pascaud, C.; Patel, G. D.; Peppel, E.; Peters, S.; Phillips, H. T.; Phillips, J. P.; Pichler, Ch.; Pilgram, W.; Pitzl, D.; Prosi, R.; Raupach, F.; Rauschnabel, K.; Reimer, P.; Ribarics, P.; Riech, V.; Riedlberger, J.; Rietz, M.; Robertson, S. M.; Robmann, P.; Roosen, R.; Rostovtsev, A.; Royon, C.; Rudowicz, M.; Ruffer, M.; Rusakov, S.; Rybicki, K.; Ryseck, E.; Sacton, J.; Sahlmann, N.; Sanchez, E.; Sankey, D. P.; Savitsky, M.; Schacht, P.; Schleper, P.; von Schlippe, W.; Schmidt, C.; Schmidt, D.; Schmitz, W.; Schröder, V.; Schulz, M.; Schwind, A.; Scobel, W.; Seehausen, U.; Sell, R.; Seman, M.; Semenov, A.; Shekelyan, V.; Sheviakov, I.; Shooshtari, H.; Siegmon, G.; Siewert, U.; Sirois, Y.; Skillicorn, I. O.; Smirnov, P.; Smith, J. R.; Smolik, L.; Soloviev, Y.; Spitzer, H.; Staroba, P.; Steenbock, M.; Steffen, P.; Steinberg, R.; Steiner, H.; Stella, B.; Stephens, K.; Strachota, J.; Straumann, U.; Struczinski, W.; Sutton, J. P.; Taylor, R. E.; Thompson, G.; Thompson, R. J.; Tichomirov, I.; Trenkel, C.; Truöl, P.; Tchernyshov, V.; Turnau, J.; Tutas, J.; Urban, L.; Usik, A.; Valkar, S.; Valkarova, A.; Vallee, C.; Vanesch, P.; Vartapetian, A.; Vasdik, J.; Vecko, M.; Verrecchia, P.; Vick, R.; Villet, G.; Vogel, E.; Wacker, K.; Walker, I. W.; Walther, A.; Weber, G.; Wegener, D.; Wegner, A.

1992-12-01

108

Development of radiation hard scintillators.  

National Technical Information Service (NTIS)

Substantial improvements have been made in the radiation hardness of plastic scintillators. Cylinders of scintillating materials 2.2 cm in diameter and 1 cm thick have been exposed to 10 Mrads of gamma rays at a dose rate of 1 Mrad/h in a nitrogen atmosph...

A. Pla-Dalmau D. Woods F. Markley G. Foster R. Blackburn

1992-01-01

109

Infinite Hard-Sphere System.  

National Technical Information Service (NTIS)

The time-evolution for the system of infinitely many particles in space interacting by a hard-sphere potential is constructed. Examples abound of configurations of the infinite system having more than one solution to the Newtonian equations of motion. A r...

R. K. Alexander

1975-01-01

110

Fatigue of biomaterials: Hard tissues  

Microsoft Academic Search

The fatigue and fracture behavior of hard tissues are topics of considerable interest today. This special group of organic materials comprises the mineralized (roughly 50% mineral by volume or greater) and load-bearing tissues of the human body; it includes bone, cementum, dentin and enamel. An understanding of their fatigue behavior and the influence of loading conditions and physiological factors (e.g.

D. Arola; D. Bajaj; J. Ivancik; H. Majd; D. Zhang

2010-01-01

111

Collision statistics in sheared inelastic hard spheres.  

PubMed

The dynamics of sheared inelastic-hard-sphere systems is studied using nonequilibrium molecular-dynamics simulations and direct simulation Monte Carlo. In the molecular-dynamics simulations Lees-Edwards boundary conditions are used to impose the shear. The dimensions of the simulation box are chosen to ensure that the systems are homogeneous and that the shear is applied uniformly. Various system properties are monitored, including the one-particle velocity distribution, granular temperature, stress tensor, collision rates, and time between collisions. The one-particle velocity distribution is found to agree reasonably well with an anisotropic Gaussian distribution, with only a slight overpopulation of the high-velocity tails. The velocity distribution is strongly anisotropic, especially at lower densities and lower values of the coefficient of restitution, with the largest variance in the direction of shear. The density dependence of the compressibility factor of the sheared inelastic-hard-sphere system is quite similar to that of elastic-hard-sphere fluids. As the systems become more inelastic, the glancing collisions begin to dominate over more direct, head-on collisions. Examination of the distribution of the times between collisions indicates that the collisions experienced by the particles are strongly correlated in the highly inelastic systems. A comparison of the simulation data is made with direct Monte Carlo simulation of the Enskog equation. Results of the kinetic model of Montanero [J. Fluid Mech. 389, 391 (1999)] based on the Enskog equation are also included. In general, good agreement is found for high-density, weakly inelastic systems. PMID:19518225

Bannerman, Marcus N; Green, Thomas E; Grassia, Paul; Lue, Leo

2009-04-22

112

Hardness determination by means of a FEM-supported simulation of nanoindentation and applications in thin hard coatings  

Microsoft Academic Search

In nanoindentation procedures, due to indenter tip form deviations from its ideal geometry and the limited indentation depth, the contact region between the indenter and the specimen cannot be accurately determined. In this way, up to now, the hardness values are approximated by means of empirical methods with restricted accuracy, in a wide range of applications. In the frame of

K.-D. Bouzakis; N. Michailidis; G. Skordaris

2005-01-01

113

Influence of the interposition of ceramic spacers on the degree of conversion and the hardness of resin cements.  

PubMed

This study evaluated: I) the effect of photo-activation through ceramics on the degree of conversion (DC) and on the Knoop hardness (KHN) of light- and dual-cured resin cements; and II) two different protocols for obtaining the spectra of uncured materials, to determine the DC of a dual-cured resin cement. Thin films of cements were photo-activated through ceramics [feldspathic porcelain (FP); lithium disilicate glass-ceramics of low translucency (e.max-LT), medium opacity (e.max-MO) and high translucency (e.max-HT); glass-infiltrated alumina composite (IC) and polycrystalline zirconia (ZR)] with thicknesses of 1.5 and 2.0 mm. DC was analyzed by Fourier transform infrared (FTIR) spectroscopy. Two protocols were used to obtain the spectra of the uncured materials: I) base and catalyst pastes were mixed, and II) thin films of base and catalyst pastes were obtained separately, and an average was obtained. KHN assessment was performed with cylindrical specimens. The results were analyzed by ANOVA and Tukey's test (?= 0.05). The light-cured cement showed higher DC (61.9%) than the dual-cured cement (55.7%). The DC varied as follows: FP (65.4%), e.max-HT (65.1%), e.max-LT (61.8%), e.max-MO (60.9%), ZR (54.8%), and IC (44.9%). The light-cured cement showed lower KHN (22.0) than the dual-cured (25.6) cement. The cements cured under 1.5 mm spacers showed higher KHN (26.2) than when polymerized under 2.0 mm ceramics (21.3). Regarding the two protocols, there were significant differences only in three groups. Thus, both methods can be considered appropriate. The physical and mechanical properties of resin cements may be affected by the thickness and microstructure of the ceramic material interposed during photo-activation. PMID:24036978

Calgaro, Patricia Angélica Milani; Furuse, Adilson Yoshio; Correr, Gisele Maria; Ornaghi, Bárbara Pick; Gonzaga, Carla Castiglia

114

Quantitative Trait Loci Associated with Milling and Baking Quality in a Soft × Hard Wheat Cross  

Microsoft Academic Search

Hybridization between soft and hard wheat creates new associations among loci. Advantages include an increase Interclass hybridization between soft and hard wheat (Triticum in genetic diversity, a potential increase in grain yield, aestivum L.) results in new genetic combinations of potential value. and transfer of pest resistance genes. Both May et al. We investigated whether interclass hybridization could improve end-

Kimberly Garland Campbell; Patrick L. Finney; Christine J. Bergman; Daisy G. Gualberto; James A. Anderson; Michael J. Giroux; Dimuth Siritunga; Jiaqian Zhu; Francois Gendre; Catherine Roué; Aliette Vérel; Mark E. Sorrells

2001-01-01

115

First-principles study on hard\\/soft samarium-cobalt\\/cobalt-iron nanocomposite magnetic materials  

Microsoft Academic Search

More than a decade ago, exchange-spring permanent magnets containing soft and hard magnetic phases have been proposed to enlarge maximum energy product values through exchange coupling between the magnetically soft and hard phases. Indeed some later experiments have shown some promises in this regard. However, there are still many pending fundamental issues in the understanding and enhancement of the exchange

Dangxin Wu

2008-01-01

116

Magnon softening in exchange-coupled hard-soft nanocomposites  

NASA Astrophysics Data System (ADS)

We study spin excitations of the fully aligned state for three-dimensional nanocomposites of exchange coupled hard (SmFeN) and soft (FeCo) phases. The dipolar interaction lowers the magnon energy and controls the spin wave gap at k = 0, which closes when the amount of soft phase exceeds a critical value. With the addition of soft phase or increasing temperature the system moves to another ground state characterized by a tilting of the magnetization at the boundaries between spins of the hard and the soft phases.

Belemuk, A. M.; Chui, S. T.

2013-03-01

117

Hard spheres out of equilibrium  

NASA Astrophysics Data System (ADS)

In this thesis, experiments and simulations are combined to investigate the nonequilibrium behaviour of hard spheres. In the first chapters we use Molecular Dynamics simulations to investigate the dynamic glass transition of polydisperse hard spheres. We show that this dynamic transition is accompanied by a thermodynamic signature. The higher-order derivatives of the pressure change abruptly at the dynamic glass transition. If a system is compressed beyond this dynamic transition, the pressure increases until it diverges when the system is completely jammed. The density at which the pressure diverges depends on the compression speed. We proceed with experiments on colloidal polymethylmethacrylate (PMMA) particles which closely resemble hard spheres. We investigate the effect of compression using gravity and electric field gradients on the nucleation and on the glass transition. The transition from glass to crystal is gradual and is strongly effected by gravity. We go back to computer simulations to investigate two different techniques to calculate the rate at which a hard-sphere system nucleates. We find that the two techniques yield similar results for the nucleation rate as well as the critical nucleus shape. From this we conclude that the simulation techniques are valid. A combination of simulations and experiments is used to study the nucleation of hard spheres on seed structures. We initiate the nucleation with a seed of particles kept in place by optical tweezers. We show that whereas the nucleation itself can be well described as an equilibrium process, the growth after nucleation can not. We demonstrate that defects play an important role in the growth of the crystal. Colloidal hard spheres can also be driven out of equilibrium using shear. We perform experiments on an equilibrium fluid phase below the coexistence density of the fluid. We show that we can induce order in an equilibrium fluid using oscillatory shear. We find five different phases for varying frequency and amplitude: four known phases and one new phase. The formation of all phases occurs via nucleation and growth and the melting, when the shear is stopped, starts on the edges and near the defects of the crystal phases. In the final chapter, we investigate the interactions between rough colloidal particles in the presence of polymers. We investigate whether surface roughness can be used to reduce the depletion attraction. We find that when the polymer is smaller than the surface roughness the attraction can be reduced significantly compared to smooth colloids.

Hermes, M.

2010-05-01

118

Value Engineering  

Microsoft Academic Search

This paper defines value engineering, shows why it is necessary, and emphasizes the engineer's responsibility for using engineering disciplines in the design of a product. Recognizing that value engineering is a duty of the professional engineer, the paper stresses application of value engineering to attain Armed Services goals, and reduce costs while speeding up delivery of the weapon system. Many

A. Zappacosta

1962-01-01

119

Hard Photodisintegration of 3He  

NASA Astrophysics Data System (ADS)

Large angle photodisintegration of two nucleons from the 3He nucleus is studied within the framework of the hard rescattering model (HRM). In the HRM the incoming photon is absorbed by one nucleon's valence quark that then undergoes a hard rescattering reaction with a valence quark from the second nucleon producing two nucleons emerging at large transverse momentum . Parameter free cross sections for pp and pn break up channels are calculated through the input of experimental cross sections on pp and pn elastic scattering. The calculated cross section for pp breakup and its predicted energy dependency are in good agreement with recent experimental data. Predictions on spectator momentum distributions and helicity transfer are also presented.

Granados, Carlos

2011-02-01

120

Weld cladding of hard surfaces  

NASA Astrophysics Data System (ADS)

A literature study about clad welding of hard surfaces on steel is performed. The purpose was to see what kind of methods are mainly used, and particular attention is paid to clad welding of rolls. The main impression from this study is that several methods are in use. Some of these must be considered as 'too exotic' for the aim of the program, such as laser build-up welding. However, clad welding of hard surfaces to rolls is widely used around the world, and there is no need for particularly advanced welding methods to perform the work. The welding consumables and the way the welding is carried out is of more important character. The report will give some comments to this, and hopefully will give a short review of the current technology in this field.

Habrekke, T.

1993-02-01

121

Ultrasonic material hardness depth measurement  

DOEpatents

The invention is an ultrasonic surface hardness depth measurement apparatus and method permitting rapid determination of hardness depth of shafts, rods, tubes and other cylindrical parts. The apparatus of the invention has a part handler, sensor, ultrasonic electronics component, computer, computer instruction sets, and may include a display screen. The part handler has a vessel filled with a couplant, and a part rotator for rotating a cylindrical metal part with respect to the sensor. The part handler further has a surface follower upon which the sensor is mounted, thereby maintaining a constant distance between the sensor and the exterior surface of the cylindrical metal part. The sensor is mounted so that a front surface of the sensor is within the vessel with couplant between the front surface of the sensor and the part.

Good, Morris S. (Richland, WA); Schuster, George J. (Kennewick, WA); Skorpik, James R. (Kennewick, WA)

1997-01-01

122

Cyclic strength of hard metals  

Microsoft Academic Search

The fatigue limit of the titanium carbide and tungsten carbide alloys investigated on a basis of 5·108 cycles lies in the range (20–30)·107 Pa, and is thus comparable with the endurance of type ShKh high-carbon (~1% C-Mn-Si-Cr) ball-bearing steels. The strength and character of fracture of the hard metals are determined by the properties and structural state of their phase

N. N. Sereda; A. K. Gerikhanov; M. S. Koval'chenko; L. G. Pedanov

1985-01-01

123

BGO crystals - radiation hard scintillators  

Microsoft Academic Search

A new version of the Bridgman technique of Bi4Ge3O12 (BGO) crystal growth was developed. The first radiation hardness measurement of new BGO grown by this technique shows excellent characteristics. The optical transmission at a peak emission 0.48 mum of these crystals degraded by no more than 10% when irradiated by photons from 60Co decay up to a total dose of

V. V. Yanovsky; V. A. Chizhov; V. M. Skorikov

1991-01-01

124

Splitting (complicated) surfaces is hard  

Microsoft Academic Search

Let M be an orientable combinatorial surface. A cycle on M is splitting if it has no self-intersections and it partitions M into two components, neither of which is homeomorphic to a disk. In other words, splitting cycles are simple, separating, and non-contractible. We prove that finding the shortest splitting cycle on a combinatorial surface is NP-hard but fixed-parameter tractable

Erin W. Chambers; Éric Colin De Verdière; Jeff Erickson; Francis Lazarus; Kim Whittlesey

2008-01-01

125

Splitting (complicated) surfaces is hard  

Microsoft Academic Search

Let M be an orientable surface without boundary. A cycle on M is splitting if it has no self-intersections and it partitions M into two components, neither homeomorphic to a disk. In other words, splitting cycles are simple, separating, and non-contractible. We prove that finding the shortest splitting cycle on a combinatorial surface is NP-hard but fixed-parameter tractable with respect

Erin W. Chambers; Éric Colin De Verdière; Jeff Erickson; Francis Lazarus; Kim Whittlesey

2006-01-01

126

What's on Your Hard Drive?  

Microsoft Academic Search

What’s on Your Hard Drive? Whether you love ’em or hate ’em, dev tools play an integral role in a programmer’s existence. They were (hopefully!) designed to make your job easier, although all too often the exact opposite seems to be the case. Is there a tool so exceptionally brilliant that you just can’t live without it? Have you encountered

Charlene O'Hanlon

2006-01-01

127

Impact of aging on radiation hardness  

SciTech Connect

Burn-in effects are used to demonstrate the potential impact of thermally activated aging effects on functional and parametric radiation hardness. These results have implications on hardness assurance testing. Techniques for characterizing aging effects are proposed.

Shaneyfelt, M.R.; Winokur, P.S.; Fleetwood, D.M. [and others

1997-07-01

128

Polarization observables in hard rescattering mechanism of deuteron photodisintegration  

NASA Astrophysics Data System (ADS)

Polarization properties of high energy photodisintegration of the deuteron are studied within the framework of the hard rescattering mechanism (HRM). In HRM, a quark of one nucleon knocked-out by the incoming photon rescatters with a quark of the other nucleon leading to the production of two nucleons with high relative momentum. Summation of all relevant quark rescattering amplitudes allows us to express the scattering amplitude of the reaction through the convolution of a hard photon-quark interaction vertex, the large angle p-n scattering amplitude and the low momentum deuteron wave function. Within HRM, it is demonstrated that the polarization observables in hard photodisintegration of the deuteron can be expressed through the five helicity amplitudes of NN scattering at high momentum transfer. At 90° CM scattering HRM predicts the dominance of the isovector channel of hard pn rescattering, and it explains the observed smallness of induced, Py and transfered, Cx polarizations without invoking the argument of helicity conservation. Namely, HRM predicts that Py and Cx are proportional to the ?5 helicity amplitude which vanishes at ?cm=90° due to symmetry reasons. HRM predicts also a nonzero value for Cz in the helicity-conserving regime and a positive ? asymmetry which is related to the dominance of the isovector channel in the hard reinteraction. We extend our calculations to the region where large polarization effects are observed in pp scattering as well as give predictions for angular dependences.

Sargsian, Misak M.

2004-05-01

129

Surface Integrity Generated by Precision Hard Turning  

Microsoft Academic Search

Rolling contact fatigue tests were conducted to find the effect of precision hard turning. The tests showed that hard turning provides as good a fatigue performance as grinding. Hard turning produces compressive residual stresses in a deep subsurface, which contribute to a long fatigue life. The effect of cutting parameters on residual stress was investigated in order to find why

Y. Matsumoto; F. Hashimoto; G. Lahoti

1999-01-01

130

The maximum hardness principle implies the hard/soft acid/base rule  

NASA Astrophysics Data System (ADS)

A recent paper [P. W. Ayers, J. Chem. Phys122, 141102 (2005)] considered the hard/soft acid/base exchange reaction, showing that the products associated with the hard/soft acid/base rule (in which the hard acid and hard base are bound, as are the soft acid and soft base) have lower energy than the alternative (in which the hard acid and soft base would have been bound and similarly the soft acid and hard base). Here we show that the maximum hardness principle also predicts this result. Unlike the previous derivation, we do not need to make any assumptions about the relative strength of the acids and bases.

Chattaraj, Pratim K.; Ayers, Paul W.

2005-08-01

131

Local hardness equalization: Exploiting the ambiguity  

NASA Astrophysics Data System (ADS)

In the density-functional theory of chemical reactivity, the local hardness is known to be an ambiguous concept. The mathematical structure associated with this problematic situation is elaborated and three common definitions for the local hardness are critically examined: the frontier local hardness [S. K. Ghosh, Chem. Phys. Lett. 172, 77 (1990)], the total local hardness [S. K. Ghosh and M. Berkowitz, J. Chem. Phys. 83, 2976 (1985)], and the unconstrained local hardness [P. W. Ayers and R. G. Parr, J. Am. Chem. Soc. 122, 2010 (2000)]. The frontier local hardness has particularly nice properties: (a) it has smaller norm than most, if not all, other choices of the local hardness and (b) it is ``unbiased'' in an information-theoretic sense. For the ground electronic state of a molecular system, the frontier local hardness is equal to the global hardness. For an electronic system in its ground state, both the chemical potential and the frontier local hardness are equalized. The frontier local hardness equalization principle provides a computational approach for designing reagents with desirable chemical reactivity profiles.

Ayers, Paul W.; Parr, Robert G.

2008-05-01

132

Hard sphere gas state equation  

NASA Astrophysics Data System (ADS)

The dynamic evolution of a gas of N hard spheres determines the equation of state once the equilibrium is reached, after a short transient. The system is investigated in the thermodynamic limit. The algorithms based on a tricky management of the collisions list allow to simulate up to N=10 spheres, rendering the statistical error sufficiently small in simulations involving 10 collisions. The effect of boundaries is discussed, and, to avoid any dependence, periodic boundary conditions are chosen in a box, whose edge is much larger than the spheres radius. The initial state is the symmetric close packing and, by reducing the hard spheres radius, we follow the evolution of the mean free path as a function of the density y (where y is the ratio between the volume of the spheres and the total volume). We observe the solid-fluid first-order phase transition and follow the fluid branch until the hard spheres gas is very dilute. The phase transition is well resolved due to the improved statistics and to the choice, as order parameter, of the mean free path rather than Z=PV/NkT, which has a singularity at zero mean free path. The equations of state in the fluid and solid branches are compared with the Taylor series for the mean free path, obtained from the virial expansions of Z. The second-order truncations P2(y), appear to provide the best fit to the mean free path. This suggests an approximation to Z as Z=1+B2y/P2(y), where B2 is the second virial coefficient.

Rambaldi, Sandro; Salustri, Giovanna; Benedetti, Carlo

2006-02-01

133

The Hard Problem of Cooperation  

PubMed Central

Based on individual variation in cooperative inclinations, we define the “hard problem of cooperation” as that of achieving high levels of cooperation in a group of non-cooperative types. Can the hard problem be solved by institutions with monitoring and sanctions? In a laboratory experiment we find that the answer is affirmative if the institution is imposed on the group but negative if development of the institution is left to the group to vote on. In the experiment, participants were divided into groups of either cooperative types or non-cooperative types depending on their behavior in a public goods game. In these homogeneous groups they repeatedly played a public goods game regulated by an institution that incorporated several of the key properties identified by Ostrom: operational rules, monitoring, rewards, punishments, and (in one condition) change of rules. When change of rules was not possible and punishments were set to be high, groups of both types generally abided by operational rules demanding high contributions to the common good, and thereby achieved high levels of payoffs. Under less severe rules, both types of groups did worse but non-cooperative types did worst. Thus, non-cooperative groups profited the most from being governed by an institution demanding high contributions and employing high punishments. Nevertheless, in a condition where change of rules through voting was made possible, development of the institution in this direction was more often voted down in groups of non-cooperative types. We discuss the relevance of the hard problem and fit our results into a bigger picture of institutional and individual determinants of cooperative behavior.

Eriksson, Kimmo; Strimling, Pontus

2012-01-01

134

Breaking Symmetry of Interchangeable Variables and Values  

Microsoft Academic Search

A common type of symmetry is when both variables and values par- tition into interchangeable sets. Polynomial methods have been introduced to eliminate all symmetric solutions introduced by such interchangeability. Unfor- tunately, whilst eliminating all symmetric solutions is tr actable in this case, prun- ing all symmetric values is NP-hard. We introduce a new global constraint called SIGLEX and its

Yat Chiu Law; Jimmy Ho-man Lee; Toby Walsh; J. Y. K. Yip

2007-01-01

135

Crystallization of hard aspherical particles  

NASA Astrophysics Data System (ADS)

We use numerical simulations to study the crystallization of monodisperse systems of hard aspherical particles. We find that particle shape and crystallizability can be easily related to each other when particles are characterized in terms of two simple and experimentally accessible order parameters: one based on the particle surface-to-volume ratio and the other on the angular distribution of the perturbations away from the ideal spherical shape. We present a phase diagram obtained by exploring the crystallizability of 487 different particle shapes across the two-order-parameter spectrum. Finally, we consider the physical properties of the crystalline structures accessible to aspherical particles and discuss limits and relevance of our results.

Miller, William L.; Bozorgui, Behnaz; Cacciuto, Angelo

2010-04-01

136

The value of value congruence.  

PubMed

Research on value congruence has attempted to explain why value congruence leads to positive outcomes, but few of these explanations have been tested empirically. In this article, the authors develop and test a theoretical model that integrates 4 key explanations of value congruence effects, which are framed in terms of communication, predictability, interpersonal attraction, and trust. These constructs are used to explain the process by which value congruence relates to job satisfaction, organizational identification, and intent to stay in the organization, after taking psychological need fulfillment into account. Data from a heterogeneous sample of employees from 4 organizations indicate that the relationships that link individual and organizational values to outcomes are explained primarily by the trust that employees place in the organization and its members, followed by communication, and, to a lesser extent, interpersonal attraction. Polynomial regression analyses reveal that the relationships emanating from individual and organizational values often deviated from the idealized value congruence relationship that underlies previous theory and research. The authors' results also show that individual and organizational values exhibited small but significant relationships with job satisfaction and organizational identification that bypassed the mediators in their model, indicating that additional explanations of value congruence effects should be pursued in future research. PMID:19450005

Edwards, Jeffrey R; Cable, Daniel M

2009-05-01

137

Valuing Wildlands  

Treesearch

Environmental Risk Assessment and Management from a Landscape Perspective. ... The question is, of course, fundamental to economic models and modes of ... The value of wildlands is derived from human use of resources, as well as ...

138

Are Short GRBs Really Hard?  

SciTech Connect

Thanks to the rapid position notice and response by HETE-2 and Swift, the X-ray afterglow emissions have been found for four recent short gamma-ray bursts (GRBs; GRB 050509b, GRB 050709, GRB 050724, and GRB 050813). The positions of three out of four short GRBs are coincident with galaxies with no current or recent star formation. This discovery tightens the case for a different origin for short and long GRBs. On the other hand, from the prompt emission point of view, a short GRB shows a harder spectrum comparing to that of the long duration GRBs according to the BATSE observations. We investigate the prompt emission properties of four short GRBs observed by Swift/BAT. We found that the hardness of all four BAT short GRBs is in between the BATSE range for short and long GRBs. We will discuss the spectral properties of short GRBs including the short GRB sample of Konus-Wind and HETE-2 to understand the hard nature of the BATSE short GRBs.

Sakamoto, T.; Cummings, J. [NASA Goddard Space Flight Center (United States); Barbier, L.; Barthelmy, S.; Gehrels, N.; Parsons, A.; Tueller, J.; Cline, T. [NASA Goddard Space Flight Center (United States); Fenimore, E.; Palmer, D. [Los Alamos National Laboratory (United States); Hullinger, D. [NASA Goddard Space Flight Center (United States); University of Maryland (United States); Krimm, H.; Markwardt, C. [NASA Goddard Space Flight Center (United States); Sato, G. [Institute of Space and Astronautical Science (United States); Aptekar, R.; Golenetskii, S.; Mazets, E.; Pal'shin, V. [Ioffe Physico-Technical Institute (Russian Federation); Ricker, G. [Massachusetts Institute of Technology (United States); Lamb, D. [University of Chicago (United States)] (and others)

2006-05-19

139

Molecular hardness and softness, local hardness and softness, hardness and softness kernels, and relations among these quantities  

Microsoft Academic Search

Hardness and softness kernels &eegr;(r,r’) and s(r,r’) are defined for the ground state of an atomic or molecular electronic system, and the previously defined local hardness and softness &eegr;(r) and s(r) and global hardness and softness &eegr; and S are obtained from them. The physical meaning of s(r), as a charge capacitance, is discussed (following Huheey and Politzer), and two

Max Berkowitz; Robert G. Parr

1988-01-01

140

Indentation Load Effect on Young's Modulus and Hardness of Porous Sialon Ceramic by Depth Sensing Indentation Tests  

NASA Astrophysics Data System (ADS)

Depth sensing indentation (DSI) tests at the range of 200-1800 mN are performed on porous sialon ceramic to determine the indentation load on Young's modulus and hardness values. The Young modulus and hardness (Dynamic and Martens) values are deduced by analysing the unloading segments of the DSI test load-displacement curves using the Oliver-Pharr method. It is found that Young's modulus Er, the dynamic hardness HD and the Martens hardness HM exhibit significant indentation load dependences. The values of Young's modulus and hardness decrease with the increasing indentation load, as a result of indentation load effect. The experimental hf/hm ratios lower than the critical value 0.7, with hm being the maximum penetration depth during loading and hf the final unloading depth, indicate that our sample shows the work hardening behaviour.

Osman, Sahin

2007-11-01

141

Microfluidic traps for hard-wired operations on droplets.  

PubMed

We present microfluidic modules (traps) that allow us to lock, shift, dose and merge micro-aliquots of liquid precisely. The precision is hard-wired into the geometry of the device: small values of the capillary number guarantee reproducibility of operation over a range of rates of flow that need not be controlled precisely. The modules can be integrated into systems that perform complicated protocols on micro-droplets while not requiring precision in forcing the flow. PMID:23970204

Korczyk, Piotr M; Derzsi, Ladislav; Jakie?a, S?awomir; Garstecki, Piotr

2013-08-22

142

The hard hexagon partition function for complex fugacity  

NASA Astrophysics Data System (ADS)

We study the analyticity of the partition function of the hard hexagon model in the complex fugacity plane by computing zeros and transfer matrix eigenvalues for large finite size systems. We find that the partition function per site computed by Baxter in the thermodynamic limit for positive real values of the fugacity is not sufficient to describe the analyticity in the full complex fugacity plane. We also obtain a new algebraic equation for the low density partition function per site.

Assis, M.; Jacobsen, J. L.; Jensen, I.; Maillard, J.-M.; McCoy, B. M.

2013-11-01

143

Crop Values  

NSDL National Science Digital Library

While economic data on crop values are strictly commercial/ agricultural summaries, they can be useful as surrogate indices of land use/ cover change, or in estimating food subsidies (e.g. waste grain) for wildlife. Posted by the US Department of Agriculture (USDA) Economics and Statistics System at Cornell University, the site contains the "annual marketing year average prices and value of production of principal crops". Principal crops include barley (all, feed, and malting), hay, oats, rye, wheat (all, winter, durum, and other spring), upland and American-pima cotton and cottonseed, corn, dry beans, flaxseed, peanuts, sorghum, soybeans, sunflowers, and rice. These data are provided by the National Agricultural Statistics Service (USDA).

2005-12-07

144

Crop Values  

NSDL National Science Digital Library

While economic data on crop values are strictly commercial/ agricultural summaries, they can be useful as surrogate indices of land use/ cover change, or in estimating food subsidies (e.g. waste grain) for wildlife. Posted by the US Department of Agriculture (USDA) Economics and Statistics System at Cornell University, the site contains the "annual marketing year average prices and value of production of principal crops". Principal crops include barley (all, feed, and malting), hay, oats, rye, wheat (all, winter, durum, and other spring), upland and American-pima cotton and cottonseed, corn, dry beans, flaxseed, peanuts, sorghum, soybeans, sunflowers, and rice. These data are provided by the National Agricultural Statistics Service (USDA).

145

Water hardness control by detergent builders  

Microsoft Academic Search

Commercial detergent additives to control water hardness are of three main types, sequestrant, precipitant or ion-exchange\\u000a builders. These builders lower the free hardness ion (Ca+2, Mg+2) concentration in a wash system by different mechanisms. An electrometric experimental method was used to evaluate the relative\\u000a water hardness control performances of different builder-types under conditions closely simulating those of detergent’s end-use.\\u000a Experimental

M. K. Nagarajan; H. L. Paine

1984-01-01

146

A scaling rule of indentation hardness of semiconductors  

NASA Astrophysics Data System (ADS)

We report a scaling rule of the indentation hardness of semiconductor crystals from room temperature to their melting. The Vickers hardness of fifteen semiconductors, Si, Ge, SiC, AlN, GaN, GaP, GaAs, GaSb, InP, InAs, InSb, ZnO, ZnSe, ZnTe and CdTe, has been investigated from room temperature to their melting points. The temperature dependences of the hardness H v of eleven of these semiconductors, namely those with a cubic structure, obey a universal relationship when H v and the temperature T are scaled respectively by the shear modulus G and by G b ^3 / k _B, with b being the magnitude of the Burgers vector and k B the Boltzmann constant. The scaling rule is the same as that found for the temperature dependence of the critical shear stress ? c for the 111 < 1bar1 0> slip system. The result leads a link between hardness and macroscopic yielding (dislocation motion). The relationshipH v = (70 ˜ 100) ? c is deduced for the cubic semiconductors is about ten times as large as the value for metals.

Yonenaga, Ichiro; Suzuki, Takayoshi

2003-03-01

147

Soft copy versus hard copy reading in digital mammography.  

PubMed

The objective of this study was to compare soft copy reading at a mammography work station with hard copy reading of full-field digital mammographic images. Mammograms of 60 patients ( n = 29 malignant, n = 31 benign) performed with full-field digital mammography (Senographe 2000D, GE, Buc, France) were evaluated. Reading was performed based on hard copy prints (Scopix, Agfa, Leverkusen, Germany) and on 2 k x 2.5 k high-resolution monitors (Sun Ultra 60, Sun Microsystems, Palo Alto, California, USA). Four readers with different levels of experience in mammography categorized the mammograms according to the BI-RADS classification. The comparative study was performed by four readers, and at least 2 months elapsed between the reading sessions. Postprocessing, of course, was available only at the work station (windowing and leveling, zooming, inversion). Sensitivity, specificity, and positive predictive value were evaluated. Diagnostic accuracy of the evaluation was determined. Sensitivity for malignant lesions in hard copy versus soft copy reading was 97% vs 90%, 97% vs 97%, 93% vs 97%, and 76% vs 76% for the four readers, respectively. Specificity was 52% vs 68%, 58% vs 74%, 65% vs 48%, and 61% vs 68%. Accuracy for the classification of malignant lesions according to the BI-RADS categories showed no difference between hard copy and soft copy reading. Soft copy reading is possible with the available system and enables radiologists to use the advantages of a digital system. PMID:14749966

Obenauer, Silvia; Hermann, Klaus-Peter; Marten, Katharina; Luftner-Nagel, Susanne; von Heyden, Dorit; Skaane, Per; Grabbe, Eckhardt

2004-01-30

148

Kinetics of hardness evolution during annealing of gamma-irradiated polycarbonate  

SciTech Connect

This study focuses on the evolution in microhardness values that accompany isothermal annealing in gamma-irradiated polycarbonate (PC). Hardness increases with increasing annealing time, temperature, and gamma radiation dose. A model composed of a mixture of first and zero order structure relaxation is proposed to interpret the hardness data. The rate constant data fit the Arrhenius equation, and the corresponding activation energy decreases with increasing dose. The extent of structural relaxation that controls the hardness in post-annealed PC increases with increasing annealing temperature and dose. The model demonstrates that hardness evolution in PC is an endothermic process. By contrast, when the model is applied to irradiated poly(methyl methacrylate) and hydroxyethyl methacrylate copolymer, hardness evolution is an exothermic process.

Yeh, S. H.; Chen, P. Y.; Lee, Sanboh [Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Harmon, Julie [Department of Chemistry, University of South Florida, Tampa, Florida 33620-5250 (United States)

2012-12-01

149

Ruin Value  

Microsoft Academic Search

In this article I consider Albert Speer’s theory of ruin value through a discussion of the work of two Weimar theorists of ruination, Ernst Jünger and Walter Benjamin. The first section of the article relates Speer’s original theory of ruins to Nazi ideology. After this consideration of the Nazi obsession with ruination, the second division of the article explores the

Mark Featherstone

2005-01-01

150

Place Value  

NSDL National Science Digital Library

The answers to these FAQ from the Teacher2Teacher service at The Math Forum @ Drexel contain many suggestions for providing students with practice on using place value skills. They include ideas contributed by T2T Associates and teacher participants. There are links to Ask Dr. Math resources, children's literature connections, and outside websites with related resources.

Math Forum, Teacher2Teacher FAQ; The Math Forum @ Drexel

2000-01-01

151

Value Added  

ERIC Educational Resources Information Center

|This article profiles retiring values teacher Gene Doxey and describes his foundational contributions to the students of California's Ramona Unified School District. Every one of the Ramona Unified School District's 7,200 students is eventually funneled through Doxey's Contemporary Issues class, a required rite of passage between elementary…

Welch, Matt

2004-01-01

152

An inverse problem for Gibbs fields with hard core potential  

NASA Astrophysics Data System (ADS)

It is well known that for a regular stable potential of pair interaction and a small value of activity one can define the corresponding Gibbs field (a measure on the space of configurations of points in Rd). In this paper we consider a converse problem. Namely, we show that for a sufficiently small constant ?1 and a sufficiently small function ?2(x), x?Rd, that is equal to zero in a neighborhood of the origin, there exist a hard core pair potential and a value of activity such that ?1 is the density and ?2 is the pair correlation function of the corresponding Gibbs field.

Koralov, Leonid

2007-05-01

153

Measurements of the hard-x-ray reflectivity of iridium  

SciTech Connect

In connection with the design of a hard-x-ray telescope for the Constellation X-Ray Observatory we measured the reflectivity of an iridium-coated zerodur substrate as a function of angle at 55, 60, 70, and 80 keV at the National Synchrotron Light Source of Brookhaven National Laboratory. The optical constants were derived from the reflectivity data. The real component of the index of refraction is in excellent agreement with theoretical values at all four energies. However, the imaginary component, which is related to the mass attenuation coefficient, is 50% to 70% larger at 55, 60, and 70 keV than theoretical values.

Romaine, S.; Bruni, R.; Gorenstein, P.; Zhong, Z

2007-01-10

154

Value Numbering  

Microsoft Academic Search

SUMMARY Value numbering is a compiler-based program analysis method that allows redundant computations to be removed. This paper compares hash-based approaches derived from the classic local algorithm1 with partitioning approaches based on the work of Alpern, Wegman, and Zadeck2. Historically, the hash-based algorithm has been applied to single basic blocks or extended basic blocks. We have improved the technique to

Preston Briggs; Keith D. Cooper; L. Taylor Simpson

1997-01-01

155

Expected Value  

NSDL National Science Digital Library

In this activity, students will use the random integer command on their graphing calculators to simulate rolling a die. They will then use operations on lists to analyze the probability of rolling the first 1 on the 1st roll, 2nd roll, and so on and finally find the expected value. Teacher notes explain in detail how to perform these actions on the graphing calculator.

2008-10-17

156

Fundamental Value and Market Value  

Microsoft Academic Search

Much of James Tobin's professional life has been devoted to studying the interrelationship between the goods and financial markets. His general equilibrium approaches stresses the interaction of the demand for financial assets with the decision to accumulate productive capital. His emphasis on q, the ratio of market value of assets to their replacement cost, has shaped how students of the

William C. Brainard; Matthew D. Shapiro; John B. Shoven

1990-01-01

157

Radial variations in modulus and hardness in SCS-6 silicon carbide fibers  

SciTech Connect

The mechanical properties of SCS-6 SiC fibers were measured as a function of fiber radius using nanoindentation techniques. Hardness and Young`s modulus were characterized for the material in all of the major regions of these fibers: the carbon core, the graphitic core coating, the inner SiC sheath, and the outer SiC sheath. The carbon core of the fibers was determined to be uniform in properties but extremely compliant. Young`s modulus of 28 GPa and a hardness of 4.2 GPa were measured. The graphitic core coating was found to exhibit considerable anelasticity and to have both a low modulus (21 GPa) and a low hardness (1.7 GPa). The inner sheath of the fiber, which contained a varying chemistry, showed a sharp increase in stiffness and hardness from the inner core. Modulus and hardness increased by an order of magnitude over just 1 or 2 {micro}m when transversing radially away from the core into the SiC. This change in properties was pronounced and clearly defined. The outer sheath, which contained a uniform chemistry and microstructure, was consistently stiff and hard when transversing radially. The average modulus and hardness for the full fiber was 333 GPa. The values reported for Young`s modulus and hardness clearly showed that the mechanical properties of SCS SiC fibers exhibit dramatic changes across their diameters.

Mann, A.B.; Weihs, T.P. [Johns Hopkins Univ., Baltimore, MD (United States). Dept. of Materials Science and Engineering; Balooch, M.; Kinney, J.H. [Lawrence Livermore National Lab., CA (United States). Dept. of Chemistry and Materials Science

1999-01-01

158

Influence of Substrate Hardness on the Properties of PVD Hard Coatings  

Microsoft Academic Search

Nowadays, hard coatings based on transition metal nitrides are extensively used for materials protection and particularly to improve the lifetime and performance of various cutting and forming tools. Practically, hard coatings need to be deposited on different kinds of substrate materials in different application areas. The physical properties, such as hardness, of the substrate may have evident influence on the

X. T. Zeng; Y. C. Liu; J. Wei; P. Holiday

2008-01-01

159

After Hard Drives—What Comes Next?  

Microsoft Academic Search

There are numerous emerging nonvolatile memory technologies, which have been proposed as being capable of replacing hard disk drives (HDDs). In this paper, the prospects for these alternative technologies to displace HDDs in 2020 are analyzed. In order to compare technologies, projections were made of storage density and performance in year 2020 for both hard disks and the alternative technologies,

Mark H. Kryder; Chang Soo Kim

2009-01-01

160

"Hard Science" for Gifted 1st Graders  

ERIC Educational Resources Information Center

|"Hard Science" is designed to teach 1st grade gifted students accurate and high level science concepts. It is based upon their experience of the world and attempts to build a foundation for continued love and enjoyment of science. "Hard Science" provides field experiences and opportunities for hands-on discovery working beside experts in the…

DeGennaro, April

2006-01-01

161

HARD SPRING WHEAT TECHNICAL COMMITTEE 2007 CROP  

Technology Transfer Automated Retrieval System (TEKTRAN)

Twelve experimental lines of hard spring wheat were grown at up to five locations in 2007 and evaluated for kernel, milling, and bread baking quality against the check variety Glenn. Samples of wheat were submitted through the Wheat Quality Council and processed and milled at the USDA Hard Red Spri...

162

Etch durable spin-on hard mask  

Microsoft Academic Search

As decreasing the device feature size, the film stack structure used in resist process is also changing. Especially multilayer stack film structure is getting popular for pattern formation on critical layers. Our approach is to form a spin-on hard mask film with high etch resistance by introduction of a new baking function. The results show that a spin-on hard mask

Makoto Muramatsu; Mitsuaki Iwashita; Takashi Kondo; Hisashi Hirose; Seiji Fujimoto

2011-01-01

163

Roller burnishing of hard turned surfaces  

Microsoft Academic Search

In a hard roller burnishing operation, a hydrostatically borne ceramic ball rolls over the component surface under high pressures. The roughness peaks are flattened and the quality of the workpiece surface is improved. When combined with hard turning, this process provides a manufacturing alternative to grinding and honing operations.The studies determined optimum working parameter ranges. Parameter settings were shown to

F. Klocke; J. Liermann

1998-01-01

164

Rockwell Hardness Measurement of Metallic Materials.  

National Technical Information Service (NTIS)

The Rockwell hardness test continues to be applied as a tool for assessing the properties of a product while the tolerances on the acceptable material hardness have become tighter and tighter. The once-thought-of manufacturing tool has developed into a me...

S. R. Low

2001-01-01

165

Radiation hardness studies of CVD diamond detectors  

Microsoft Academic Search

The inherent properties of diamond make it an ideal material for tracking detectors especially in the high rate, high radiation environments of future colliders such as the LHC. In order to survive in this environment, detectors must be radiation hard. We have constructed charged particle detectors using high quality CVD diamond and performed radiation hardness tests on them. The signal

C. Bauer; I. Baumann; C. Colledani; J. Conway; P. Delpierre; F. Djama; W. Dulinski; A. Fallou; K. K. Gan; R. S. Gilmore; E. Grigoriev; G. Hallewell; S. Han; T. Hessing; K. Honschied; J. Hrubec; D. Husson; H. Kagan; D. Kania; R. Kass; W. Kinnison; K. T. Knöpfle; M. Krammer; T. J. Llewellyn; P. F. Manfredi; L. S. Pan; H. Pernegger; M. Pernicka; R. Plano; V. Re; S. Roe; A. Rudge; M. Schaeffer; S. Schnetzer; S. Somalwar; V. Speziali; R. Stone; R. J. Tapper; R. Tesarek; W. Trischuk; R. Turchetta; G. B. Thomson; R. Wagner; P. Weilhammer; C. White; H. Ziock; M. Zoeller

1995-01-01

166

Rad Hard Active Media For Calorimeters  

Microsoft Academic Search

Zero-degree calorimeters have limited space and extreme levels of radiation. A simple, low cost, radiation hard design uses tungsten metal as the absorber and a suitable liquid as the Cerenkov radiator. In other applications a PPAC (Parallel Plate Avalanche Counter) operating with a suitable atmospheric-pressure gas is an attractive active material for a calorimeter. It can be made radiation hard

E. Norbeck; J. E. Olson; A. Moeller; Y. Onel

2006-01-01

167

Hard Metal Alveolitis Accompanied by Rheumatoid Arthritis  

Microsoft Academic Search

Hard metal lung diseases (HML) are rare, and complex to diagnose. We describe the case of a patient with allergic alveolitis accompanied by rheumatoid arthritis. A sharpener of hard metal by trade, our patient was a 45-year-old, nonsmoking Caucasian female who experienced symptoms of cough and phlegm, and dyspnea on exertion. Preliminary lung findings were inspiratory rales in both basal

Paula A. Hahtola; Ritva E. Järvenpää; Kari Lounatmaa; Jorma J. Mattila; Immo Rantala; Jukka A. Uitti; Seppo Sutinen

2000-01-01

168

Numerical prediction of microstructure and hardness in multicycle simulations  

NASA Astrophysics Data System (ADS)

Thermal-microstructural predictions are made and compared to physical simulations of heat-affected zones in multipass and weaved welds. The microstructural prediction algorithm includes reaustenitization kinetics, grain growth, austenite decomposition kinetics, hardness, and tempering. Microstructural simulation of weaved welds requires that the algorithm include transient reaustenitization, austenite decomposition for arbitrary thermal cycles including during reheating, and tempering. Material properties for each of these phenomena are taken from the best available literature. The numerical predictions are compared with the results of physical simulations made at the Metals Technology Laboratory, CANMET, on a Gleeble 1500 simulator. Thermal histories used in the physical simulations included single-pass welds, isothermal tempering, two-cycle, and three-cycle welds. The two-and three-cycle welds include temper-bead and weaved-weld simulations. A recurring theme in the analysis is the significant variation found in the material properties for the same grade of steel. This affected all the material properties used including those governing reaustenitization, austenite grain growth, austenite decomposition, and hardness. Hardness measurements taken from the literature show a variation of ±5 to 30 HV on the same sample. Alloy differences within the allowable range also led to hardness variations of ±30 HV for the heat-affected zone of multipass welds. The predicted hardnesses agree extremely well with those taken from the physical simulations. Some differences due to problems with the austenite decomposition properties were noted in that bainite formation was predicted to occur somewhat more rapidly than was found experimentally. Reaustenitization values predicted during the rapid excursions to intercritical temperatures were also in good qualitative agreement with those measured experimentally.

Oddy, A. S.; McDill, J. M. J.

1996-06-01

169

Geometric optimization for radiation hardness assurance  

NASA Astrophysics Data System (ADS)

The probability of a single event effect occurring is generally a function of the energy deposited in a sensitive volume, which is typically expressed as the absorbed dose in that volume. For short segments of high energy particle tracks, the dose due to a single event is proportional to the chord length through the sensitive volume. Thus, the distribution of dose in chord length is likely to relate to the probability of single event effects. For various geometries, a differential chord length distribution was generated and from this the dose distribution, frequency mean chord length, and dose mean chord length were calculated. In every case, the dose mean chord length was greater than the frequency mean chord length by a minimum of 26% and increased with the eccentricity of the volume. The large value of the dose mean chord length relative to the frequency mean chord length demonstrates the need to consider rare, long-chord-length crossings in radiation hardness testing, despite their relatively low probability of occurrence.

Northum, J.; Guetersloh, S.

170

Studies on surface activity of linear alkylbenzene sulfonates II: Effect of water hardness  

Microsoft Academic Search

Adsorption behavior of a mixture of homologs and isomers of sodium linear alkylbenzene sulfonates from their aqueous solutions\\u000a in hard water at the solution\\/air interface has been investigated. Increasing the concentration of surfactant in hard water\\u000a results in the precipitation of the surfactant, which starts redissolving in the solution with further increases in surfactant\\u000a concentration beyond a certain value characteristic

Raj Kumar; S. G. T. Bhat

1987-01-01

171

The socio-cultural value of New Zealand wilderness  

Treesearch

Title: The socio-cultural value of New Zealand wilderness ... however, social changes such as urbanization, globalization, increasing consumerism, and ... You may send email to rschneider@fs.fed.us to request a hard copy of this publication.

172

Wave mechanics of two hard core quantum particles in A 1-D box  

Microsoft Academic Search

The wave mechanics of two impenetrable hard core particles in 1-D box is analyzed. Each particle in the box behaves like an independent entity represented by a {\\\\it macro-orbital} (a kind of pair waveform). While the expectation value of their interaction, $$, vanishes for every state of two particles, the expectation value of their relative separation, $$, satisfies $ \\\\ge

Yatendra S. Jain

2004-01-01

173

TOXICITY OF COPPER TO CUTTHROAT TROUT ('SALMO CLARKI') UNDER DIFFERENT CONDITIONS OF ALKALINITY, PH, AND HARDNESS  

EPA Science Inventory

Median lethal concentration (96-h LC50) values for acute copper toxicity to 3-10 g cutthroat trout (Salmo clarki) have been determined for nine different combinations of alkalinity, hardness, and pH. Equilibrium calculations were performed on the copper LC50 values; seven differe...

174

Adolescents' Perceptions of the Primary Values of Television Programming  

Microsoft Academic Search

This study of middle and high school students finds some support for cultivation theory. Some values associated with television—i.e., “hard work yields rewards” or “good wins over evil”—are more valued by higher versus lower exposed-to-television watchers. There were interactions. The ultimate triumph of hard work and good conduct, for example, were associated with viewing sports programs. Those who watched a

W. James Potter

1990-01-01

175

Hard X-ray astronomy with balloons  

NASA Astrophysics Data System (ADS)

The hard X-ray studies of cosmic X-ray sources carried out with the balloon-borne instruments launched from Hyderabad (India) during 1968-1990 period are discussed. Advantages of making hard X-ray astronomy observations from Hyderabad are pointed out and the X-ray telescopes used in these studies are briefly described. A summary of the important results obtained from these studies on the galactic binary X-ray sources, a few extragalactic objects and the diffuse cosmic X-ray background, is presented. The important results include detection of hard X-ray flares in Sco X-1 and Cyg X-1, 4.8 hr intensity modulation in Cyg X-3, hard X-ray pulsations in the X-ray pulsars, energy spectra of Cyg X-1, Her X-1, 3C 273 and the diffuse Cosmic X-ray background, the correlated optical and hard X-ray intensity variations and the size of the hard X-ray emitting region in the Crab Nebula. Future hard X-ray studies planned to be carried out from Hyderabad are briefly described.

Agrawal, P. C.

1991-08-01

176

Hard Choices for Individual Situations.  

ERIC Educational Resources Information Center

This paper focuses on faculty use of a decision-making process for complex situations. The analysis part of the process describes and compares course management software focusing on: technical specifications, instructional design values,tools and features, ease of use, and standards compliance. The extensive comparisons provide faculty with…

Landon, Bruce

177

Hardness measurements of Ar[sup +]-beam treated polyimide by depth-sensing ultra low load indentation  

SciTech Connect

Polyimide Kapton and spin-cast polyamic acid (PAA) on sapphire have been implanted with 1 MeV Ar ions to a dose of 4.7[times]10[sup 15] cm[sup [minus]2] at ambient temperature. The properties of both pristine and implanted surfaces were characterized by a depth-sensing low-load indentation technique. Experiments were carried out to investigate the effects of substrate, indentation rate, relaxation, and indentation technique. The results showed that (1) hardness was depth-dependent and decreased with increasing indentation depth, (2) measurements of the ion beam hardened surface with the untreated material as a substrate underestimated the hardness while measurements over the sapphire substrate overestimated it, (3) the effects of loading/unloading rates were apparent in the load displacement results, and (4) hardness values measured using the force modulation technique showed very little depth dependence. The hardness value at 100 nm depth is used for comparison purposes since the hardness value at this depth was almost independent of substrate, indentation rate, and indentation method. The hardness of Kapton, which was measured using the techniques described herein, was increased by over 30 times after Ar implantation, from 0.43 to 13 GPa at 100 nm indentation depth. A similar increase in hardness was also observed for polyamic acid. This result suggests that spin-cast PAA film may have potential technological applications for protective coatings where hardness and wear resistance are required.

Lee, E.H.; Lee, Y.; Oliver, W.C.; Mansur, L.K. (Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States))

1993-02-01

178

Hardness of CaF2 and BaF2 Solid Lubricants at 25 to 670 Deg C.  

National Technical Information Service (NTIS)

Plastic deformation is a prominent factor in determining the lubricating value of solid lubricants. Little information is available and its direct measurement is difficult so hardness, which is an indirect measure of this property was determined for fluor...

D. L. Deadmore H. E. Sliney

1987-01-01

179

Effects of water hardness on the toxicity of manganese to developing brown trout (Salmo trutta)  

SciTech Connect

Manganese is a common constituent of point and nonpoint discharges from mining and smelting activities. Available data indicate that Mn is acutely toxic at relatively high aqueous concentrations, when compared with trace metals, and its toxicity is affected by water hardness. Little information is available regarding the chronic toxicity of manganese. Early-life-stage (ELS) tests were conducted to determine the toxicity of manganese to brown trout (Salmo trutta) and to evaluate the extent to which water hardness (ranging from 30 to 450 mg/L as CaCO{sub 3}) affects the chronic toxicity of Mn. Water hardness of significantly affected Mn chronic toxicity, with toxicity decreasing with increasing hardness. Decreased survival was the predominant effect noted in the 30-mg/L hardness experiment, while significant effects on growth (as measured by changes in body weight) were observed in both the 150- and 450-mg/L hardness experiments. Twenty-five percent inhibition concentration (IC25) values, based on the combined endpoints (i.e., survival and body weight), were 4.67, 5.59, and 8.68 mg Mn/L (based on measured Mn concentration) at hardness levels of approximately 30, 150, and 450 mg/L as CaCO{sub 3}, respectively.

Stubblefield, W.A.; Garrison, T.D.; Hockett, J.R. [ENSR Corp., Fort Collins, CO (United States); Brinkman, S.F.; Davies, P.H.; McIntyre, M.W. [Colorado Div. of Wildlife, Fort Collins, CO (United States)

1997-10-01

180

Public Notification: “Instant Hard Rod” Contains Undeclared ...  

Center for Drug Evaluation (CDER)

... analysis confirmed that “Instant Hard Rod” contains ... pressure, high cholesterol or heart disease often ... sexual enhancement, weight loss, and body ... More results from www.fda.gov/drugs/resourcesforyou/consumers

181

Amorphous metals for hard-tissue prosthesis  

NASA Astrophysics Data System (ADS)

Owing to a unique atomic structure lacking microstructural defects, glassy metals demonstrate certain universal properties that are attractive for load-bearing biomedical-implant applications. These include a superb strength, which gives rise to very high hardness and a potential for minimizing wear and associated adverse biological reactions, and a relatively low modulus, which enables high elasticity and holds a promise for mitigating stress shielding. There are, however, other non-universal properties specific to particular amorphous metal alloys that are inferior to presently used biometals and may be below acceptable limits for hard-tissue prosthesis. In this article, features of the performance of amorphous metals relevant to hard-tissue prosthesis are surveyed and contrasted to those of the current state of the art, and guidelines for development of new biocompatible amorphous metal alloys suitable for hard-tissue prosthesis are proposed.

Demetriou, Marios D.; Wiest, Aaron; Hofmann, Douglas C.; Johnson, William L.; Han, Bo; Wolfson, Nikolaj; Wang, Gongyao; Liaw, Peter K.

2010-02-01

182

Hard Rock Cutting with Abrasion Jet.  

National Technical Information Service (NTIS)

The usefulness of high-pressure waterjets in cutting hard materials such as concrete, rock, and minerals was significantly improved by entraining selective abrasives into the waterjet. In fact, good entrainment of abrasives into the waterjet was found to ...

G. G. Yie

1983-01-01

183

Take a Long, Hard Look  

ERIC Educational Resources Information Center

The mooted development of a set of core British values demands a thorough re-examination of what it means to be British. The author argues that British people need to look at Britishness a bit more as others see them. For many the experience of Britishness was brutishness and it is still seen that way in the Middle East and not just by those in…

Mackney, Paul

2008-01-01

184

Investigation Of Tool Wear In Hard Turning Using Taguchi Method  

NASA Astrophysics Data System (ADS)

Hard turning is a machining process defined of hardness higher than 45 HRC under appropriate cutting tools and cutting speed. The objective of this paper is to investigate the optimum process parameters for a particular work piece-tool material combination. . In this study, three levels of each parameters viz. Hardness (HRC), Speed(mm/min), Feed(mm/rev) and three different tool materials are evaluated for process quality characteristics such as tool wear. The three different tool materials used are High CBN, Low CBN, Mixed ceramic. AISI H 11 was taken as work piece material. The experiment is designed using Taguchi Method. The results obtained from the experiments are transformed into signal to noise (S/N) ratio and used to optimize the value of tool wear. The analysis of variance (ANOVA) is performed to indentify the statistical significance of parameters. The final results of experimental investigation are presented in this paper. The conclusions arrived at are critically discussed at the end.

Chaudhari, Y. D.

2013-03-01

185

Hardness and stress-corrosion of rubber dam clamps.  

PubMed

Rubber dam clamps fracture infrequently during use. There are no American National Standards Institute or International Standards Organization standards for their manufacture. The purpose of this study was to measure the hardness of the clamps and test their resistance to a stress-corrosion test. Upper molar, lower molar, and premolar clamps were obtained from two manufacturers (A, B). The Rockwell C hardness at four sites on the bow of each clamp was then determined. Fresh clamps were placed on blocks corresponding to the average buccal-lingual dimension of the tooth on which they would be used. These blocks were then submerged in room temperature 5.25% sodium hypochlorite for 20 min and then allowed to air dry for 30 min. This was repeated 10 times. Rockwell C hardness values ranged from C30 to 38, with the clamps of manufacturer B being significantly harder. None of the clamps from manufacturer B cracked or corroded. When a third batch received from manufacturer A was tested in the same manner, none of the clamps fractured or corroded either. PMID:9545952

Svec, T A; Powers, J M; Ladd, G D

1997-06-01

186

Laser Ablatin of Dental Hard Tissue  

SciTech Connect

This paper discusses ablation of dental hard tissue using pulsed lasers. It focuses particularly on the relevant tissue and laser parameters and some of the basic ablation processes that are likely to occur. The importance of interstitial water and its phase transitions is discussed in some detail along with the ablation processes that may or may not directly involve water. The interplay between tissue parameters and laser parameters in the outcome of the removal of dental hard tissue is discussed in detail.

Seka, W.; Rechmann, P.; Featherstone, J.D.B.; Fried, D.

2007-07-31

187

Laboratory studies of hard rock for CAES  

SciTech Connect

A program is summarized which investigated the properties of hard rock specimens, from formations suitable for CAES that are subject to the conditions envisioned for a CAES cavern by means of laboratory scale testing. It is concluded that although the compressive and tensile strengths are adversely influenced by a Compressed Air Energy Storage Cavern environment, the reduced failure strength of hard rocks is sufficiently high to indicate that a CAES plant could be operated satisfactorily.

Fossum, A.F.

1980-10-01

188

Laboratory studies of hard rock for CAES  

NASA Astrophysics Data System (ADS)

The properties of hard rock specimens, from formations suitable for compressed air energy storage (CAES) that are subject to the conditions envisioned for a CAES cavern, were investigated by means of laboratory testing. It was concluded that although the compressive and tensile strengths are adversely influenced by a CAES cavern environment, the reduced failure strength of hard rocks is sufficiently high to indicate that a CAES plant could be operated satisfactorily.

Fossum, A. F.

1980-10-01

189

Constitutive properties of hard-alpha titanium  

Microsoft Academic Search

The flow and fracture behavior of hard-alpha Ti was studied as a function of nitrogen content, stress state, strain rate,\\u000a and temperature. Hard-alpha Ti specimens with nitrogen contents ranging from 2 to 11.6 wt pct were fabricated by powder-metallurgy\\u000a techniques. Stress-strain curves were obtained under various states of stress by performing uniaxial compression, indirection\\u000a tension, indentation, and plane-strain compression tests

K. S. Chan; G. R. Leverant; L. Perocchi

2000-01-01

190

On the hardness of coated systems  

Microsoft Academic Search

The hardness of a number of coated systems has been measured using a variety of experimental techniques ranging from traditional macro-Vickers indentation to ultra-low-load depth-sensing nanoindentation. This has allowed the hardness response to be measured over scales ranging from those less than the coating thickness, where a coating-dominated response is expected, to much more macroscopic scales where system behaviour is

A. M. Korsunsky; M. R. McGurk; S. J. Bull; T. F. Page

1998-01-01

191

Proton structure function. Soft and hard Pomerons  

Microsoft Academic Search

Regge models for proton structure function with and without a hard Pomeron contribution are compared with all available data in the region $W>3$ GeV, $Q^{2}\\\\leq 3000$ GeV$^{2}$ and $x<0.75$. It is shown that the data do not support a hard Pomeron term in $\\\\gamma^{*} p$ amplitude. Moreover, the data support the idea that the soft Pomeron, either is a double

P. Desgrolard; E. Martynov

2001-01-01

192

Short-hard gamma-ray bursts  

Microsoft Academic Search

Two types of gamma-ray bursts (GRBs) are observed: short-duration hard spectrum GRBs and long-duration soft spectrum GRBs. For many years long GRBs were the focus of intense research while the lack of observational data limited the study of short-hard GRBs (SHBs). In 2005 a breakthrough occurred following the first detections of SHB afterglows, longer wavelength emission that follows the burst

Ehud Nakar

2007-01-01

193

Testing the Hardness of Common Minerals  

NSDL National Science Digital Library

This activity gives students practice and a chance to develop expertise in using the test for hardness in identifying common minerals. Following a discussion and an introduction to Moh's scale, the students will work in groups to test minerals whose identities are known against their standards (common substances whose hardnesses are known). Once the known minerals have been tested, the students can proceed to test unknown samples. A student worksheet and discussion questions are provided.

194

Exact second virial coefficient for dipolar hard spheres.  

PubMed

The second virial coefficient B2 for a fluid of dipolar hard spheres has been given several approximate forms valid in the limits of weak and strong interactions. They have been formulated as asymptotic expressions in a dimensionless interaction parameter ?. In this paper, B2 is determined exactly for all values of ? in both the three-dimensional case, where spheres may access the whole space and their dipole moments may be oriented in all directions, and in the quasi-two-dimensional case, where spheres have their centres bound to glide on a plane, while their dipole moments are still freely orientable in space. PMID:24158678

Virga, Epifanio G

2013-10-24

195

Controlling the jamming transition of sheared hard spheres  

NASA Astrophysics Data System (ADS)

Many applications require understanding how disordered materials flow under an external load such as a shear stress. Since external loads drive systems out of equilibrium, their behavior cannot be described solely in terms of equilibrium parameters like temperature and pressure. However, simulations and experiments show that sheared spherical particles possess an effective temperature that relates low-frequency fluctuations of various observable quantities to their associated response functions. Here, we show that the mobility of a mixture of sheared hard spheres is largely controlled by the dimensionless ratio of effective temperature to pressure, Teff/p3?, where ? is the sphere diameter. We define the effective temperature as the consistent value that relates the amplitudes of low-frequency shear stress and density fluctuations to their associated response functions. We find that the relaxation time ? characterizing the mobility depends on Teff/p3? according to two distinct mechanisms in two distinct regimes. In the solid response regime, the behavior at fixed packing fraction ? satisfies ??(-cp3?/Teff), where ? is the strain rate and c depends weakly on ?, suggesting that the effective temperature controls the average local yield strain. In the fluid response regime, ? depends on Teff/p3? as it depends on T/p3? in equilibrium. This regime comprises a large part of the hard-sphere jamming phase diagram including both near-equilibrium conditions where Teff is similar to the kinetic temperature Tkin and far-from-equilibrium conditions where TeffTkin. In particular, the dynamic jamming transition is largely controlled by the fluid-response mechanism; like equilibrium hard spheres, sheared hard spheres can flow only if low-frequency fluctuations are large enough compared to the pressure. By presenting our results in terms of the dimensionless jamming phase diagram, we show how these mechanisms likely apply to systems with soft repulsive interactions.

Haxton, Thomas

2012-02-01

196

RAD hard PROM design study  

NASA Astrophysics Data System (ADS)

The results of a preliminary study on the design of a radiation hardened fusible link programmable read-only memory (PROM) are presented. Various fuse technologies and the effects of radiation on MOS integrated circuits are surveyed. A set of design rules allowing the fabrication of a radiation hardened PROM using a Si-gate CMOS process is defined. A preliminary cell layout was completed and the programming concept defined. A block diagram is used to describe the circuit components required for a 4 K design. A design goal data sheet giving target values for the AC, DC, and radiation parameters of the circuit is presented.

1981-07-01

197

Pion Form Factor in Chiral Limit of Hard-Wall AdS/QCD Model  

SciTech Connect

We develop a formalism to calculate form factor and charge density distribution of pion in the chiral limit using the holographic dual model of QCD with hard-wall cutoff. We introduce two conjugate pion wave functions and present analytic expressions for these functions and for the pion form factor. They allow to relate such observables as the pion decay constant and the pion charge electric radius to the values of chiral condensate and hard-wall cutoff scale. The evolution of the pion form factor to large values of the momentum transfer is discussed, and results are compared to existing experimental data.

Anatoly Radyushkin; Hovhannes Grigoryan

2007-12-01

198

Dielectric and hardness measurements of planetary analog rocks in support of in-situ subsurface sampling  

NASA Astrophysics Data System (ADS)

Accurate assessment of the subsurface mechanical characteristics and how they correlate with dielectric properties is crucial to optimize future drilling and sampling investigations on planetary bodies. For 12 different types of basaltic rocks with different hardnesses, we use capacitive cells to measure the real part of the dielectric constant over the frequency range 100–1000 MHz, and a Schmidt hammer hardness tester to measure the hardness using a scale of 10–100. Our measurements suggest that the real part of the dielectric constant and rock hardness are linearly correlated. Additionally, sample hardness was linearly correlated to density. For a density ranging from 0.82 to 3.05 g/cm3, the real part of the dielectric constant ?? and rebound hardness values R ranged from ??=1.8–7.6 and R=14.16–68 for the different basalt samples. Hence, high dielectric constants imply a high rock hardness value and vice versa. We concluded that for volcanic surfaces that are analogous to the Martian surface as well as other planetary surfaces, there is an inverse correlation between drilling penetration rate based on the rotary-percussive drill method and the dielectric constant. Dielectric inversion from planetary radar probing experiments proposed herein is a crucial method to locate regions with lowest hardness and hence highest drilling penetration rate in desiccated volcanic planetary subsurfaces. The use of these cross-correlation measurements can optimize future drilling experiments and ensure that they reach their targets of opportunities, minimize losses in drilling performance, or the unnecessary use of power that will be needed for the continuity of the investigation.

ElShafie, Ahmed; Heggy, Essam

2013-09-01

199

Evaluation of surface roughness and hardness of different glass ionomer cements  

PubMed Central

Objectives: The aim of this study was to evaluate surface roughness and hardness of a nanofiller GIC, a resin-modified GIC, three conventional GICs, and a silver-reinforced GIC. Methods: For each material, 11 spcecimens were prepared and then stored in distilled water at 37 °C for 24 h. The surface roughness of 5 specimens was measured using a surface profilometer before polishing and after polishing with coarse, medium, fine, superfine aluminum oxide abrasive Sof-Lex discs respectively. The hardness of the upper surfaces of the remaining 6 specimens was measured with a Vickers microhardness measuring instrument. Results: All tested GICs showed lower surface roughness values after the polishing procedure. Surface finish of nanofiller GIC was smoother than the other tested GICs after polishing. This was followed by resin-modified GIC, Fuji II LC; then silver-reinforced GIC, Argion Molar, conventional GICs, Aqua Ionofil Plus, Fuji IX, and Ionofil Molar, respectively. The result of the hardness test indicated that the microhardness value of silver-reinforced GIC was greater than that of the other GICs. When the hardness values of all tested GICs were compared, the differences between materials (except Aqua Ionofil Plus with Ionofil Molar and Ketac N100 with Fuji II LC (P>.05)) were found statistically significant (P<.05). Conclusions: According to the results of this study, it can be concluded that the differences in the composition of GICs may affect their surface roughness and hardness.

Bala, Oya; Arisu, Hacer Deniz; Yikilgan, Ihsan; Arslan, Seda; Gullu, Abdulkadir

2012-01-01

200

Haptic Search for Hard and Soft Spheres  

PubMed Central

In this study the saliency of hardness and softness were investigated in an active haptic search task. Two experiments were performed to explore these properties in different contexts. In Experiment 1, blindfolded participants had to grasp a bundle of spheres and determine the presence of a hard target among soft distractors or vice versa. If the difference in compliance between target and distractors was small, reaction times increased with the number of items for both features; a serial strategy was found to be used. When the difference in compliance was large, the reaction times were independent of the number of items, indicating a parallel strategy. In Experiment 2, blindfolded participants pressed their hand on a display filled with hard and soft items. In the search for a soft target, increasing reaction times with the number of items were found, but the location of target and distractors appeared to have a large influence on the search difficulty. In the search for a hard target, reaction times did not depend on the number of items. In sum, this showed that both hardness and softness are salient features.

van Polanen, Vonne; Bergmann Tiest, Wouter M.; Kappers, Astrid M. L.

2012-01-01

201

Time correlation functions of hard sphere and soft sphere fluids.  

PubMed

We explore the transition between soft particle fluids of increasing steepness to the hard sphere limit. We analyze the analytic forms of the time correlation functions used in determining transport coefficients in Green-Kubo formulas for fluids composed of particles interacting through a repulsive r(-n) potential. We focus on the steeply repulsive n--> infinity limit where the potential tends to the hard sphere interaction. Dufty [Mol. Phys. 100, 2331 (2002)] developed a theoretical framework that can be used to characterize the transition from a steeply repulsive continuous potential toward the hard sphere potential for the shear stress time correlation function. This function was shown to consist of a rapidly decaying contribution (which is singular in the steeply repulsive limit) and a slowly decaying nonsingular part which can be reasonably well represented by Enskog's prediction on times of order and in excess of the mean collision time. We extend this treatment to the bulk viscosity and thermal conductivity. We focus on the bulk viscosity (pressure) correlation function as it is purely singular for hard spheres, and has no kinetic or cross term contributions in this limit. There is no relaxation of this correlation function on the mean collision or Enskog time scale for hard spheres. We show that it is not possible to represent the steeply repulsive behavior of this function entirely in terms of a sech function, i.e., C(B)(t)=sech(a(n)t/tau(n)), where a(n) is a numerical factor, t is time, and tau(n) is a relaxation time proportional to n(-1). An additional singular function, which we call w(t), is required to obtain the correct short-time behavior of C(B)(t) and the Enskog value for the bulk viscosity. With this additional function, the value of a(n) in the n--> infinity limit is a(n)=square root of 2 which is consistent with the second moment of the time expansion of the time correlation function. We compute this function for large n and extrapolate it to n--> infinity, determining one possible analytic form. The shear stress correlation function also gives a(n)=square root of 2 in the hard sphere limit for the singular part when the sech and w functions are used. This function has a nonsingular component, even in the hard sphere limit. We explore various forms for the crossover function X(t/tau(n)) introduced by Dufty, which weights the limiting singular and nonsingular contributions to C(S)(t) particularly at intermediate times. The qualitative behavior for the heat flux time correlation function (used to obtain the thermal conductivity) is much the same as the shear case. The w(t) derived by several self-consistent extrapolations appears, within the simulation statistics, to be the same for the bulk and shear viscosity, and for the thermal conductivity cases. PMID:14995434

Bra?ka, A C; Heyes, D M

2004-02-25

202

Hard Water and Soft Soap: Dependence of Soap Performance on Water Hardness  

ERIC Educational Resources Information Center

|The demonstration of the performance of soap in different aqueous solutions, which is due to water hardness and soap formulation, is described. The demonstrations use safe, inexpensive reagents and simple glassware and equipment, introduce important everyday topics, stimulates the students to consider the wider consequences of water hardness and…

Osorio, Viktoria K. L.; de Oliveira, Wanda; El Seoud, Omar A.; Cotton, Wyatt; Easdon, Jerry

2005-01-01

203

Hard Water and Soft Soap: Dependence of Soap Performance on Water Hardness  

ERIC Educational Resources Information Center

The demonstration of the performance of soap in different aqueous solutions, which is due to water hardness and soap formulation, is described. The demonstrations use safe, inexpensive reagents and simple glassware and equipment, introduce important everyday topics, stimulates the students to consider the wider consequences of water hardness and…

Osorio, Viktoria K. L.; de Oliveira, Wanda; El Seoud, Omar A.; Cotton, Wyatt; Easdon, Jerry

2005-01-01

204

Density functional theory for molecular orientation of hard rod fluids in hard slits  

Microsoft Academic Search

A density functional theory (DFT) is used to investigate molecular orientation of hard rod fluids in a hard slit. The DFT approach combines a modified fundamental measure theory (MFMT) for excluded-volume effect with the first order thermodynamics perturbation theory for chain connectivity. In the DFT approach, the intra-molecular bonding orientation function is introduced. We consider the effects of molecular length

Da-Peng Cao; Li-Sheng Cheng; Wen-Chuan Wang

2007-01-01

205

On the quality of the hardness kernel and the Fukui function to evaluate the global hardness.  

PubMed

An approximated hardness kernel, which includes the second derivative with respect to the density of the kinetic energy, the electron-electron coulomb repulsion, and the exchange density functionals, has been tested for the calculation of the global hardness. The results obtained for a series of 40 cations and neutral systems and 16 anions represent in most cases an improvement of the results obtained using the HOMO-LUMO gap approach and indicate the viability of this approach to evaluate global hardness. In addition, the relevance of the Fukui function approximation and the role of the three components of the hardness kernel in the evaluation of the global hardness have been analyzed. PMID:17186480

Torrent-Sucarrat, Miquel; Salvador, Pedro; Geerlings, Paul; Solà, Miquel

2007-01-30

206

Scaled particle theory for hard sphere pairs. I. Mathematical structure  

NASA Astrophysics Data System (ADS)

We develop an extension of the original Reiss-Frisch-Lebowitz scaled particle theory that can serve as a predictive method for the hard sphere pair correlation function g(r). The reversible cavity creation work is analyzed both for a single spherical cavity of arbitrary size, as well as for a pair of identical such spherical cavities with variable center-to-center separation. These quantities lead directly to a prediction of g(r). Smooth connection conditions have been identified between the small-cavity situation where the work can be exactly and completely expressed in terms of g(r), and the large-cavity regime where macroscopic properties become relevant. Closure conditions emerge which produce a nonlinear integral equation that must be satisfied by the pair correlation function. This integral equation has a structure which straightforwardly generates a solution that is a power series in density. The results of this series replicate the exact second and third virial coefficients for the hard sphere system via the contact value of the pair correlation function. The predicted fourth virial coefficient is approximately 0.6% lower than the known exact value. Detailed numerical analysis of the nonlinear integral equation has been deferred to the subsequent paper.

Stillinger, Frank H.; Debenedetti, Pablo G.; Chatterjee, Swaroop

2006-11-01

207

Potential Health Impacts of Hard Water  

PubMed Central

In the past five decades or so evidence has been accumulating about an environmental factor, which appears to be influencing mortality, in particular, cardiovascular mortality, and this is the hardness of the drinking water. In addition, several epidemiological investigations have demonstrated the relation between risk for cardiovascular disease, growth retardation, reproductive failure, and other health problems and hardness of drinking water or its content of magnesium and calcium. In addition, the acidity of the water influences the reabsorption of calcium and magnesium in the renal tubule. Not only, calcium and magnesium, but other constituents also affect different health aspects. Thus, the present review attempts to explore the health effects of hard water and its constituents.

Sengupta, Pallav

2013-01-01

208

Saltwater and hard water bentonite mud  

SciTech Connect

A seawater/saltwater or hard water bentonite mud for use in drilling, and process for preparing same, comprising sequentially adding to seawater, to saltwater of a chloride concentration up to saturation, or hard water: a caustic agent; a filtration control agent; and bentonite. The resultant drilling mud meets API standards for viscosity and water loss, and is stable after aging and at tempertures in excess of 100/sup 0/ c. In another embodiment, the additives are premixed as dry ingredients and hydrated with seawater, saltwater or hard water. Unlike other bentonite drilling muds, the muds of this invention require no fresh water in their preparation, which makes them particularly useful at off-shore and remote on-shore drilling locations. The muds of this invention using bentonite further require less clay than known saltwater muds made with attapulgite, and provides superior filtration control, viscosity and stability.

Pabley, A. S.

1985-02-19

209

Uniform shear flow in dissipative gases: computer simulations of inelastic hard spheres and frictional elastic hard spheres.  

PubMed

In the preceding paper, we have conjectured that the main transport properties of a dilute gas of inelastic hard spheres (IHSs) can be satisfactorily captured by an equivalent gas of elastic hard spheres (EHSs), provided that the latter are under the action of an effective drag force and their collision rate is reduced by a factor (1+alpha)/2 (where alpha is the constant coefficient of normal restitution). In this paper we test the above expectation in a paradigmatic nonequilibrium state, namely, the simple or uniform shear flow, by performing Monte Carlo computer simulations of the Boltzmann equation for both classes of dissipative gases with a dissipation range 0.5 < or = alpha < or = 0.95 and two values of the imposed shear rate a. It is observed that the evolution toward the steady state proceeds in two stages: a short kinetic stage (strongly dependent on the initial preparation of the system) followed by a slower hydrodynamic regime that becomes increasingly less dependent on the initial state. Once conveniently scaled, the intrinsic quantities in the hydrodynamic regime depend on time, at a given value of alpha, only through the reduced shear rate a*(t) is proportional to a/square root(T(t)), until a steady state, independent of the imposed shear rate and of the initial preparation, is reached. The distortion of the steady-state velocity distribution from the local equilibrium state is measured by the shear stress, the normal stress differences, the cooling rate, the fourth and sixth cumulants, and the shape of the distribution itself. In particular, the simulation results seem to be consistent with an exponential overpopulation of the high-velocity tail. These properties are common to both the IHS and EHS systems. In addition, the EHS results are in general hardly distinguishable from the IHS ones if alpha approximately > 0.7, so that the distinct signature of the IHS gas (higher anisotropy and overpopulation) only manifests itself at relatively high dissipations. PMID:16241428

Astillero, Antonio; Santos, Andrés

2005-09-30

210

Phase behavior of hard spherical caps  

NASA Astrophysics Data System (ADS)

This work reports on the phase behavior of hard spherical caps in the interval of particle shapes delimited by the hard platelet and hemispherical cap models. These very simple model colloidal particles display a remarkably complex phase behavior featuring a competition between isotropic-nematic phase separation and clustering as well as a sequence of structures, from roundish to lacy aggregates to no ordinary hexagonal columnar mesophases, all characterized by groups of particles tending to arrange on the same spherical surface. This behavior parallels that one of many molecular systems forming micelles but here it is purely entropy-driven.

Cinacchi, Giorgio

2013-09-01

211

Novel Aspects of Hard Diffraction in QCD  

SciTech Connect

Initial- and final-state interactions from gluon-exchange, normally neglected in the parton model have a profound effect in QCD hard-scattering reactions, leading to leading-twist single-spin asymmetries, diffractive deep inelastic scattering, diffractive hard hadronic reactions, and nuclear shadowing and antishadowing--leading-twist physics not incorporated in the light-front wavefunctions of the target computed in isolation. I also discuss the use of diffraction to materialize the Fock states of a hadronic projectile and test QCD color transparency.

Brodsky, Stanley J.; /SLAC

2005-12-14

212

Rad Hard Active Media For Calorimeters  

NASA Astrophysics Data System (ADS)

Zero-degree calorimeters have limited space and extreme levels of radiation. A simple, low cost, radiation hard design uses tungsten metal as the absorber and a suitable liquid as the ?erenkov radiator. In other applications a PPAC (Parallel Plate Avalanche Counter) operating with a suitable atmospheric-pressure gas is an attractive active material for a calorimeter. It can be made radiation hard and has sufficient gain in the gas that no electronic components are needed near the detector. It works well even with the highest concentration of shower particles. For this pressure range, R134A (used in auto air conditioners) has many desirable features.

Norbeck, E.; Olson, J. E.; Moeller, A.; Onel, Y.

2006-10-01

213

Hard scattering and gauge/string duality.  

PubMed

We consider high-energy fixed-angle scattering of glueballs in confining gauge theories that have supergravity duals. Although the effective description is in terms of the scattering of strings, we find that the amplitudes are hard (power law). This is a consequence of the warped geometry of the dual theory, which has the effect that in an inertial frame the string process is never in the soft regime. At small angle we find hard and Regge behaviors in different kinematic regions. PMID:11801052

Polchinski, Joseph; Strassler, Matthew J

2002-01-02

214

Etch durable spin-on hard mask  

NASA Astrophysics Data System (ADS)

As decreasing the device feature size, the film stack structure used in resist process is also changing. Especially multilayer stack film structure is getting popular for pattern formation on critical layers. Our approach is to form a spin-on hard mask film with high etch resistance by introduction of a new baking function. The results show that a spin-on hard mask film processed by an underlayer coating system of Tokyo Electron Ltd. (TEL) has drastically improved etch resistance compared to a conventional system. We will report the availability of new underlayer system using several kinds of underlayer materials.

Muramatsu, Makoto; Iwashita, Mitsuaki; Kondo, Takashi; Hirose, Hisashi; Fujimoto, Seiji

2011-03-01

215

``Bad Metal" Conductivity of Hard Core Bosons  

NASA Astrophysics Data System (ADS)

Two dimensional hard core bosons suffer strong scattering in the high temperature resistive state at half filling. The dynamical conductivity is calculated using non perturbative tools such as continued fractions, series expansions and exact diagonalization. We find a large temperature range with linearly increasing resistivity and broad dynamical conductivity, signaling a breakdown of Boltzmann-Drude quasiparticle transport theory. At zero temperature, a high frequency peak in the dynamical conductivity appears above a ``Higgs mass'' gap, and corresponds to order parameter magnitude fluctuations. We discuss the apparent similarity between conductivity of hard core bosons and phenomenological characteristics of cuprates, including the universal scaling of Homes et. al. (Nature 430, 539 (2004)).

Lindner, Netanel; Auerbach, Assa

2010-03-01

216

Multipomeron Cuts and Hard Processes on Nuclei  

SciTech Connect

With nuclear targets comes a new scale into the pQCD description of hard processes - the saturation scale. In the saturation regime, the familiar linear k{sub perpendicular}-factorization breaks down and must be replaced by a nonlinear k{sub perpendicular}-factorization, which accounts for absorptive and multiple scattering corrections to the hard process. Predictions for partial cross sections corresponding to a fixed number of cut Pomerons (the topological cross sections) can be obtained in a surprisingly straightforward manner. We discuss some applications to deep inelastic scattering.

Schaefer, Wolfgang [Institute of Nuclear Physics PAN, ul. Radzikowskiego 152, 31-342 Krakow (Poland)

2009-03-23

217

Packings and assemblies of hard convex polyhedra  

NASA Astrophysics Data System (ADS)

Dense packings of hard polyhedra have been studied for centuries due to their mathematical aesthetic and more recently for their applications in fields such as granular matter, amorphous matter, and biology. The spontaneous organization of hard polyhedra under compression has only recently been addressed, demonstrating a plethora of assembled complex structures. The infinite pressure dense packings and the finite pressure, thermodynamically assembled structures for a given shape, however, are often different. In this talk we investigate connections between those two limits for convex polyhedra. We discuss the possibility of predicting one limit from the other, discuss some general rules, and link with previous works.

Klotsa, Daphne; Chen, Elizabeth; Damasceno, Pablo; Engel, Michael; Glotzer, Sharon

2013-03-01

218

Successes and failures with hard probes  

NASA Astrophysics Data System (ADS)

The two major pillars of searches for the Quark Gluon Plasma have been: J/ ? suppression, proposed in 1986, and observed at both SPS fixed target energies and at RHIC; and, more recently, the suppression of ? 0 with p T ?3 GeV/ c by a factor ˜5 in Au+Au central collisions, observed at RHIC in 2001, which had been predicted in advance as a consequence of Landau-Pomeranchuck-Migdal coherent (gluon) bremsstrahlung by the outgoing hard-scattered partons traversing the medium. However, new effects were discovered and the quality of the measurements greatly improved so that the clarity of the original explanations has become obscured. For instance: J/ ? suppression is the same at SpS and RHIC. Is it the QGP, comovers, something else? QCD provides beautiful explanations of ? 0 and direct ? measurements in p-p collisions but precision fits of the best theories of ? 0 suppression barely agree with the Au+Au data. Better data are needed for 10< p T <20 GeV/ c, systematic errors are needed in theory calculations, the values of parameters of the medium such as

Tannenbaum, M. J.

2009-06-01

219

Physiological, perceptual, and technical responses to on-court tennis training on hard and clay courts.  

PubMed

The aim of this study was to investigate the effect of court surface (clay vs. hard court) on technical, physiological, and perceptual responses to on-court tennis training. Four high-performance junior male players performed 2 identical training sessions on hard and clay courts, respectively. Sessions included both physical conditioning and technical elements as led by the coach. Each session was filmed for later notational analysis of stroke count and error rates. Furthermore, players wore a global positioning satellite device to measure distance covered during each session, while heart rate, countermovement jump distance, and capillary blood measures of metabolites were measured before, during, and after each session. Additionally, a respective coach and athlete rating of perceived exertion (RPE) were measured after each session. Total duration and distance covered during each session were comparable (p > 0.05; d < 0.20). Although forehand and backhands stroke volume did not differ between sessions (p > 0.05; d < 0.30), large effects for increased unforced and forced errors were present on the hard court (p > 0.05; d > 0.90). Furthermore, large effects for increased heart rate, blood lactate, and RPE values were evident on clay compared with hard courts (p > 0.05; d > 0.90). Additionally, although player and coach RPE on hard courts were similar, there were large effects for coaches to underrate the RPE of players on clay courts (p > 0.05; d > 0.90). In conclusion, training on clay courts results in trends for increased heart rate, lactate, and RPE values, suggesting that sessions on clay courts tend towards higher physiological and perceptual loads than hard courts. Furthermore, coaches seem effective at rating player RPE on hard courts but may underrate the perceived exertion of sessions on clay courts. PMID:22890497

Reid, Machar M; Duffield, Rob; Minett, Geoffrey M; Sibte, Narelle; Murphy, Alistair P; Baker, John

2013-06-01

220

Values in Education and Education in Values.  

ERIC Educational Resources Information Center

The major purpose of this book is to set out some of the key issues and debates relating to the importance of values in education and of education in values. After an introductory chapter about the concept of values and values education, part 1 provides a variety of perspectives on the values that underpin contemporary education. The introduction…

Halstead, J. Mark, Ed.; Taylor, Monica J., Ed.

221

Values in Education and Education in Values.  

ERIC Educational Resources Information Center

|The major purpose of this book is to set out some of the key issues and debates relating to the importance of values in education and of education in values. After an introductory chapter about the concept of values and values education, part 1 provides a variety of perspectives on the values that underpin contemporary education. The introduction…

Halstead, J. Mark, Ed.; Taylor, Monica J., Ed.

222

Improvement of Quench Factor Analysis in Phase and Hardness Prediction of a Quenched Steel  

NASA Astrophysics Data System (ADS)

The accurate prediction of alloys' properties introduced by heat treatment has been considered by many researchers. The advantages of such predictions are reduction of test trails and materials' consumption as well as time and energy saving. One of the most important methods to predict hardness in quenched steel parts is Quench Factor Analysis (QFA). Classical QFA is based on the Johnson-Mehl-Avrami-Kolmogorov (JMAK) equation. In this study, a modified form of the QFA based on the work by Rometsch et al. is compared with the classical QFA, and they are applied to prediction of hardness of steels. For this purpose, samples of CK60 steel were utilized as raw material. They were austenitized at 1103 K (830 °C). After quenching in different environments, they were cut and their hardness was determined. In addition, the hardness values of the samples were fitted using the classical and modified equations for the quench factor analysis and the results were compared. Results showed a significant improvement in fitted values of the hardness and proved the higher efficiency of the new method.

Kianezhad, M.; Sajjadi, S. A.

2013-05-01

223

Effects of different solutions on the surface hardness of composite resin materials.  

PubMed

In this study, the surface hardness of five light-cured composite resins were evaluated, namely: filled (Estelite), nanofil (AElite), unfilled (Valux Plus), hybrid (Tetric ceram), and Ormocer-based (Admira) composite resins. The microhardness values of composite specimens were measured at the top and bottom surfaces after 24 hours or 30 days of immersion in different solutions (tea, coffee, Turkish coffee, mouthwash, cola, and distilled water). Comparisons were made with univariate analysis of variance and Duncan's multiple range test. It was found that rough specimens of reinforced nano-hybrid composite material immersed in cola for 30 days had the lowest surface hardness (33.20), whereas rough specimens of hybrid composite material immersed in cola for 24 hours had the highest surface hardness (156.00). In both tea and coffee, the top surfaces tended to be harder than the bottom ones. In conclusion, the five different materials exhibited different hardnesses, and that the hardness values of composite materials were statistically different in different immersion solutions. PMID:19662734

Yaniko?lu, Nuran; Duymu?, Zeynep Ye?il; Yilmaz, Baykal

2009-05-01

224

Relation Between Thermal Properties of Butter and Its Hardness[1] and [2  

Microsoft Academic Search

The heat capacity of commercial and ex- perimental butter as a function o£ tem- perature was measured in an electrical input calorimeter. Hardness of the samples was measured either as seetility and vis- cosity at 10 C, or as lubrieity value at 22 C. Plots of the heat capacity curves of com- mercial butter showed major phase changes eentering at

J. W. Sherbon; S. T. Coulter

1966-01-01

225

Method for forming channels of high fluid conductivity in hard acid-soluble formations  

Microsoft Academic Search

A fracturing and acidization method for increasing the productivity of relatively hard acid-soluble formations about a perforated well, comprising the steps of producing a formation fracture containing a viscous fluid and propping agent; injecting an acid solution having a viscosity value fifty times less than the contained viscous fluid into the fluid filled fracture, thereby forming etched channels in the

W. De Vries; R. Haafkens; R. F. Luque

1981-01-01

226

Method for forming channels of high fluid conductivity in hard acid-soluble formations  

Microsoft Academic Search

A fracturing and acidization method for increasing the productivity of relatively hard acid-soluble formations about perforated well, consists of the following steps: 1) producing a formation fracture containing a viscous fluid and propping agent; 2) injecting an acid solution having a viscosity value 50 times less than the contained viscous fluid into the fluid filled fracture, thereby forming etched channels

R. Haafkens; R. F. Luque; W. De Vries

1981-01-01

227

Effect of hard bake process on LER  

NASA Astrophysics Data System (ADS)

Line-edge roughness (LER) continues to be one of the biggest challenges as the CD size shrinks down to sub 100 nm. It is shown that resist components as well as illumination conditions play a big role. Influence of resist components in both 248 and 193nm chemically amplified resist formulations has been reported but the root cause is not fully understood and may be platform or even specific formulation dependent. This paper attempts to tackle the issue from the processing side. Effects of a simple hard bake process on the LER were studied. In the hard bake process, a given resist pattern was typically baked close to the glass-transition temperature after the development process. LER improved dramatically due to melting down of the rough surface. However, the wall angle of the edge lines also started to degrade at the optimum hard bake temperature. Studies on the effects of polymer Tg, hard bake temperature and time and the issues of the process are discussed.

Padmanaban, Munirathna; Rentkiewicz, David; Lee, SangHo; Hong, Chisun; Lee, Dongkwan; Rahman, Dalil; Sakamuri, Raj; Dammel, Ralph R.

2005-05-01

228

Where the Really Hard Problems Are  

Microsoft Academic Search

It is well known that for many NP-complete problems, such as K-Sat, etc., typical cases are easy to solve; so that computationally hard cases must be rare (assuming P = NP). This paper shows that NP-complete problems can be summarized by at least one \\

Peter Cheeseman; Bob Kanefsky; William M. Taylor

1991-01-01

229

Transport properties of the hard ellipsoid fluid  

Microsoft Academic Search

Transport properties of isotropic fluids composed of hard ellipsoids of revolution are studied using molecular dynamics simulation. The self-diffusion coefficient, the shear viscosity, and the thermal conductivity are evaluated for a range of densities and elongations and are compared with the results from an Enskog kinetic theory for nonspherical bodies. The full anisotropic pair correlation function, which is required input

Peter Bereolos; Julian Talbot; Michael P. Allen; Glenn T. Evans

1993-01-01

230

Tribological laboratory evaluation of thin hard coatings  

Microsoft Academic Search

Thin hard coatings are currently being used in a large number of important tribological applications, such as metal cutting tools, forming tools, sliding bearings, seals, engine parts and other machine elements. Therefore the need to understand what decides the tribological response of a coating composite in a given tribological system, and to be able to experimentally rank different composites, is

Per Hedenqvist; Staffan Jacobson; Sture Hogmark

1997-01-01

231

Hard Times: Philosophy and the Fundamentalist Imagination  

ERIC Educational Resources Information Center

|A close reading of Gradgrind's opening monologue of Hard Times by Charles Dickens will provide the starting off point for an examination of the role and place of philosophy in the music curriculum. The Gradgrind philosophy finds easy parallel to current thinking in American education. In the fundamentalist imagination, sources of ambiguity must…

Allsup, Randall Everett

2005-01-01

232

Future trends in hard disk drives  

Microsoft Academic Search

Magnetic hard disk drives have significantly improved in size, performance and cost due to many technological innovations; including magnetoresistive heads, low noise thin film disks, PRML channels and advanced mechanical actuators and motors. By analyzing specification trends of each new disk drive design, a perspective of this evolution can be developed and design characteristics of future disk drives can be

Edward Grochowski; Roger F. Hoyt

1996-01-01

233

Thermal plasma deposition of nanophase hard coatings  

Microsoft Academic Search

Thermal plasmas offer several specific advantages for the generation of hard coatings. In particular, the high energy density of the thermal plasma allows higher precursor flow rates and a wider choice of precursors. Expansion of the plasma into a low pressure chamber offers the additional advantages that improved control over the chemistry can be achieved or that nanosize particles can

J. Heberlein; O. Postel; S. Girshick; P. McMurry; W. Gerberich; D. Iordanoglou; F. Di Fonzo; D. Neumann; A. Gidwani; M. Fan; N. Tymiak

2001-01-01

234

CRITICAL PERSISTENT CURRENTS IN HARD SUPERCONDUCTORS  

Microsoft Academic Search

Persistent currents induced in hard superconductors (HSC) were ; investigated by measuring the resulting magnetic effects. The tubular HSC ; examined were Nb powder, NbâSn, and 3Nb- Zr samples of uniform wall ; thickness and length large compared to the diameter. Experimental evidence is ; presented that in HSC the Lorentz force plays a crucial role in determining the ;

Y. B. Kim; C. F. Hempstead; A. R. Strnad

1962-01-01

235

Climate dynamics of a hard snowball Earth  

Microsoft Academic Search

The problem of deglaciating a globally ice-covered (“hard snowball”) Earth is examined using a series of general circulation model simulations. The aim is to determine the amount of CO2 that must be accumulated in the atmosphere in order to trigger deglaciation. Prior treatments of this problem have been limited to energy balance models, which are incapable of treating certain crucial

R. T. Pierrehumbert

2005-01-01

236

Hard Spring Wheat Technical Committee 2006 Crop  

Technology Transfer Automated Retrieval System (TEKTRAN)

Breeders’ experimental lines of wheat are evaluated for overall quality before being released for commercial production. The Hard Spring Wheat Technical Committee provides milling and baking quality data on breeders’ experimental lines of wheat that are annually submitted to the Wheat Quality Counc...

237

Thermal spray coatings replace hard chrome  

Microsoft Academic Search

Hard chrome plating provides good wear and erosion resistance, as well as good corrosion protection and fine surface finishes. Until a few years ago, it could also be applied at a reasonable cost. However, because of the many environmental and financial sanctions that have been imposed on the process over the past several years, cost has been on a consistent

M. Schroeder; R. Unger

1997-01-01

238

Recording physics of perpendicular media: hard layers  

Microsoft Academic Search

The results of both theoretical and experimental studies of some of the key issues related to the hard layer in perpendicular magnetic recording are presented. Among the discussed issues are the guidelines and underlying physics for choosing the optimized recording layer parameters such as thickness, specific magnetic properties, types of recording layer material, etc. Special attention is given to the

Dmitri Litvinov; Mark H. Kryder; Sakhrat Khizroev

2002-01-01

239

Registration of Anton Hard White Winter Wheat  

Technology Transfer Automated Retrieval System (TEKTRAN)

‘Anton’ (Reg. No. CV PI 651043) hard white winter wheat (Triticum aestivum L.) was developed by the USDA-ARS and the Nebraska Agricultural Experiment Station and released in December, 2007. "Anton" was selected from the cross WA691213-27/N86L177//‘Platte’. Anton primarily was released for its lo...

240

Radiation Hard Nano-FET based Biosensor  

Microsoft Academic Search

A new nano transistor based biosensor has been developed which has the potential to detect pathogens and thus protect crew safety aboard long term manned flight programs. This work outlines structures which compose the biosensor and demonstrates that the nano transistors utilized herein are total dose radiation hard. The Nano Field Effect Transistors (FET) were designed and fabricated with doped

Eric Cameron; Nirankar Mishra; Paul Winterrowd; Ron Nelson; Shiva Rastogi; Wusi Maki

241

Hard Rock Mining on the Public Land.  

National Technical Information Service (NTIS)

The Mining Law of 1872, still in force today for hard rock minerals, has the single purpose of promoting private exploration for minerals on public lands. It does not consider multiple use, environmental protection, a fair market return to the public, ret...

D. Sheridan

1977-01-01

242

Surface modulation of dental hard tissues  

Microsoft Academic Search

Tooth surfaces play a central role in the equilibrium of dental hard tissues, in which contrasting processes lead to loss or deposition of materials. The central interest of this Thesis was the modulation of tooth surfaces to control such equilibrium. Four specific studies were carried out to investigate different classes of surface modulating agents. These are: (1) Ionic modulation of

Daranee Tantbirojn

1998-01-01

243

Hard Paternalism and Clinical Research: Why Not  

Microsoft Academic Search

Jansen and Wall suggest a new way of defending hard paternalism in clinical research. They argue that non-therapeutic research exposing people to more than minimal risk should be banned on egalitarian grounds: in preventing poor decisionmakers from making bad decisions, we will promote equality of welfare. We argue that their proposal is flawed for four reasons. First, the idea of

Sarah JL Edwards; James Wilson BA

244

UMass at TREC 2003: HARD and QA  

Microsoft Academic Search

In the HARD track, we developed document metadata to correspond to query metadata requirements; implemented clarification forms based on query expansion, passage retrieval, and clustering; and retrieved variable length passages deemed most likely to be relevant. This work is discussed at length in Section 1. In the QA track, we focused on retrieving passages that were likely to contain the

Nasreen Abdul Jaleel; Andrés Corrada-emmanuel; Qi Li; Xiaoyong Liu; Courtney Wade; James Allan

2003-01-01

245

Classic and Hard-Boiled Detective Fiction.  

ERIC Educational Resources Information Center

|Through an analysis of several stories, this paper defines the similarities and differences between classic and hard-boiled detective fiction. The characters and plots of three stories are discussed: "The Red House" by A. A. Milne; "I, The Jury" by Mickey Spillane; and "League of Frightened Men" by Rex Stout. The classic detective story is…

Reilly, John M.

246

PROTEIN TEMPLATES IN HARD TISSUE ENGINEERING  

PubMed Central

Biomineralization processes such as formation of bones and teeth require controlled mineral deposition and self-assembly into hierarchical biocomposites with unique mechanical properties. Ideal biomaterials for regeneration and repair of hard tissues must be biocompatible, possess micro and macroporosity for vascular invasion, provide surface chemistry and texture that facilitate cell attachment, proliferation, differentiation of lineage specific progenitor cells, and induce deposition of calcium phosphate mineral. To expect in-vivo like cellular response several investigators have used extracellular matrix proteins as templates to recreate in-vivo microenvironment for regeneration of hard tissues. Recently, several novel methods of designing tissue repair and restoration materials using bioinspired strategies are currently being formulated. Nanoscale structured materials can be fabricated via the spontaneous organization of self-assembling proteins to construct hierarchically organized nanomaterials. The advantage of such a method is that polypeptides can be specifically designed as building blocks incorporated with molecular recognition features and spatially distributed bioactive ligands that would provide a physiological environment for cells in-vitro and in-vivo. This is a rapidly evolving area and provides a promising platform for future development of nanostructured templates for hard tissue engineering. In this review we try to highlight the importance of proteins as templates for regeneration and repair of hard tissues as well as the potential of peptide based nanomaterials for regenerative therapies.

George, Anne; Ravindran, Sriram

2010-01-01

247

BEHR: Bayesian Estimation of Hardness Ratios  

NASA Astrophysics Data System (ADS)

BEHR is a standalone command-line C program designed to quickly estimate the hardness ratios and their uncertainties for astrophysical sources. It is especially useful in the Poisson regime of low counts, and computes the proper uncertainty regardless of whether the source is detected in both passbands or not.

Park, T.; Kashyap, V. L.; Siemiginowska, A.; van Dyk, D.; Zezas, A.; Heinke, C.; Wargelin, B. J.

2013-06-01

248

‘SOFT’ VERSUS ‘HARD’ NEWS ON MICROBLOGGING NETWORKS  

Microsoft Academic Search

This article examines the variability of produsage (the hybridization of production and consumption) within popular social media by introducing semantic network analysis of information communication on Twitter. Utilizing user data (n[2,254,806]), the study examines the dynamics of produsage (a) as a function of user activity and (b) whether produsage levels vary based on either ‘soft’ or ‘hard’ news information. The

Tyler J. Horan

2012-01-01

249

A Method for Measuring the Hardness of the Surface Layer on Hot Forging Dies Using a Nanoindenter  

NASA Astrophysics Data System (ADS)

The properties and characteristics of the surface layer of forging dies are critical for understanding and controlling wear. However, the surface layer is very thin, and appropriate property measurements are difficult to obtain. The objective of the present study is to determine if nanoindenter testing provides a reliable method, which could be used to measure the surface hardness in forging die steels. To test the reliability of nanoindenter testing, nanoindenter values for two quenched and tempered steels (FX and H13) are compared to microhardness and macrohardness values. These steels were heat treated for various times to produce specimens with different values of hardness. The heat-treated specimens were tested using three different instruments—a Rockwell hardness tester for macrohardness, a Vickers hardness tester for microhardness, and a nanoindenter tester for fine scale evaluation of hardness. The results of this study indicate that nanoindenter values obtained using a Nanoindenter XP Machine with a Berkovich indenter reliably correlate with Rockwell C macrohardness values, and with Vickers HV microhardness values. Consequently, nanoindenter testing can provide reliable results for analyzing the surface layer of hot forging dies.

Mencin, P.; van Tyne, C. J.; Levy, B. S.

2009-11-01

250

Integrated criteria of gamma-ray bursts spectral hardness  

NASA Astrophysics Data System (ADS)

Most part of gamma-ray bursts (GRBs) spectra are well described by Band model with following parameters: ?, ? (spectral indices in low and high energy bands) and Epeak (energy of spectral peak). For several GRB parameter ? characterizing the spectral shape in the region up to some hundred MeV (for example, GRB100724B). Moreover, Band spectrum of GRB080916C covering 6 orders of magnitude. Until recently spectral hardness parameter H32 (the ratio of total counts in the 100 - 300 keV and 50 - 100 keV energy range) was used for additional classification events on hard and soft, for GRBs groups selection on hardness and duration distributions (subgroup of intermediate bursts) and so on. However, H32 is defined in energy intervals 50-100 keV and 100-300 keV, but for some GRB Epeak> 300 keV and this value is outside regions of H32 definition. Thus, parameter H32 is incompletely represents spectral properties of such events. Basing on Band model we introduce new integral criteria could be used in the wide energy band for data analysis in past experiments such as BATSE (0.02 - 2 MeV), COMPTEL (0.8 - 30 MeV); EGRET (20 MeV - 30 GeV); in now operated experiments Fermi (8 keV - 1MeV, 200 keV - 40 MeV and 300 MeV - 300 GeV), AGILE (18 - 60 keV and 30 MeV - 50 GeV) and in future experiments: GAMMA-400 (0.1 - 3000 GeV) and so on. In the present work spectral parameters taken from BATSE and from Fermi catalogues were analyzed and the new integral criteria were investigated. Results of data studying have shown that new criteria allow making GRB classification including intermediate bursts subgroup separation.

Arkhangelskaja, I. V.; Voevodina, E. V.; Zenin, A. A.

2013-02-01

251

CONDENSED MATTER: STRUCTURE, MECHANICAL AND THERMAL PROPERTIES: Crystal Structure and High Hardness Mechanism of Orthorhomic Si2N2O  

Microsoft Academic Search

A quasi-single-phase orthorombic Si2N2O compound is obtained by hot-pressing sintering using homogeneous precursors as raw materials under nitrogen atmosphere. The bulk hardness of orthorombic Si2N2O (o-Si2N2O) is investigated by a nanoindenter experiment; the results show that o-Si2N2O with maximal value about 19GPa has a high hardness covalent crystal besides beta-Si3N4. It is discovered that the high hardness is mainly attributed

Lan-Tian Xiong; Mao-Sheng Cao; Zhi-Ling Hou

2009-01-01

252

The effect of chromium implantation on the hardness, elastic modulus, and residual stress of Al2O3  

Microsoft Academic Search

A mechanical properties microprobe was used to obtain the values of hardness and elastic modulus for a-axis and c-axis oriented single crystals of sapphire implanted with chromium (150 to 180 keV) at room temperature. Implantation caused an increase in the hardness with no detectable effect on the modulus. The effect of implantation on the apparent yield effect exhibited by nearly

M. E. O'Hern; C. J. McHargue; C. W. White; G. C. Farlow

1990-01-01

253

Determination of monotonic stress-strain curve of hard materials from ultra-low-load indentation tests  

Microsoft Academic Search

A method has been proposed to determine the stress-strain curve of hard materials from ultra-low-load indentation tests using geometrically similar indenters. The hardness-flow stress, and characteristic plastic strain-cone angle correlations, for conical indenters, were obtained from a number of calculations with different stress-strain curves using the finite element code ABAQUS. The flow stress values thus obtained, lie between that predicted

S. Jayaraman; G. T. Hahn; W. C. Oliver; C. A. Rubin; P. C. Bastias

1998-01-01

254

Interfacial phenomena in hard-rod fluids  

NASA Astrophysics Data System (ADS)

This thesis addresses questions of interfacial ordering in hard-rod fluids at coexistence of the isotropic and nematic phases and in their contact with simple model substrates. It is organized as follows. Chapter II provides some background information about the relation between the statistical mechanical and thermodynamical level of descriptions of bulk hard-rod fluids, as well as introduces the asymptotically exact Onsager model, and some basic facts of interfacial thermodynamics. Chapter III represents studies of the simplest free IN interface in a fluid of monodisperse Onsager hard rods. For the analysis of this system we develop an efficient perturbative method to determine the (biaxial) one-particle distribution function in inhomogeneous systems. Studies of the free planar isotropic-nematic interfaces are continued in Chapter IV, where they are considered in binary mixtures of hard rods. For sufficiently different particle shapes the bulk phase diagrams of these mixtures exhibit a triple point, where an isotropic (I) phase coexists with two nematic phases (N1 and N2) of different composition. For all explored mixtures we find that upon approach of the triple point the IN2 interface shows complete wetting by an intervening N1 film. We compute the surface tension of isotropic-nematic interfaces, and find a remarkable increase with fractionation. These studies are complemented by an analysis of bulk phase behavior and interfacial properties of nonadditive binary mixtures of thin and thick hard rods in Chapter V. The formulation of this model was motivated by recent experiments in the group of Fraden, who explored the phase behavior of a mixture of viruses with different effective diameters. In our model, species of the same types are considered as interacting with the hard-core repulsive potential, whereas the excluded volume for dissimilar rods is taken to be larger (smaller) then for the pure hard rods. Such a nonadditivity enhances (reduces) fractionation at the isotropic-nematic (IN) coexistence and may induce (suppress) a demixing of the high-density nematic phase into two nematic phases of different composition (N1 and N2). Studies of their interfaces show an increase of the surface tension with fractionation at the IN interface, and complete wetting of the IN2 interface by the N1 phase upon approach of the triple point coexistence. In all explored cases bulk and interfacial properties of the nonadditive mixtures exhibit a surprising similarity with the properties of additive mixtures of larger diameter ratio. In Chapter VI we consider properties of a monodisperse hard-rod fluid in contact with the single wall (W). Studies of surface properties of a fluid of Onsager hard rods represent significant numerical difficulties, therefore we consider a simpler model fluid of hard rods with a restricted number of allowed orientations. Within this model, known as the Zwanzig model, we explore the thermodynamic properties of a fluid of monodisperse hard rods in contact with a model substrate represented by a hard wall with a short-ranged attractive or repulsive ``tail''. The attraction enhances the orientational ordering near the wall in both isotropic and nematic phases, and shifts the transition from uniaxial (U) to biaxial (B) symmetry in the isotropic surface layer to lower chemical potentials, whereas the wetting properties of the substrate remain similar to those of the pure hard wall. The soft repulsion reduces the density in the surface layer, which leads to the shift (or even suppression) of the UB transition, and strong modification of wetting properties. At the WI interface one always finds the wetting transition at sufficiently large repulsion, whereas a drying transition at the WN interface is observed only for sufficiently long-ranged potentials. In Chapter VII we explore some limitations of models of hard-rod fluids with a finite number of allowed orientations. Within Onsager's second virial theory we construct their bulk phase diagrams. For a one-component fluid, we show that the discretization of the orien

Shundyak, K. Y.

2004-05-01

255

Value of Travel Time.  

National Technical Information Service (NTIS)

The Record includes 6 papers covering important areas of travel time value analysis, such as travel time value theory, conceptual problems in travel time value, methods of deriving travel time values, review of empirical travel time value studies, applica...

R. Gronau

1976-01-01

256

Bond-orientational analysis of hard-disk and hard-sphere structures  

NASA Astrophysics Data System (ADS)

We report the bond-orientational analysis results for the thermodynamic, random, and homogeneously sheared inelastic structures of hard-disks and hard-spheres. The thermodynamic structures show a sharp rise in the order across the freezing transition. The random structures show the absence of crystallization. The homogeneously sheared structures get ordered at a packing fraction higher than the thermodynamic freezing packing fraction, due to the suppression of crystal nucleation. On shear ordering, strings of close-packed hard-disks in two dimensions and close-packed layers of hard-spheres in three dimensions, oriented along the velocity direction, slide past each other. Such a flow creates a considerable amount of fourfold order in two dimensions and body-centered-tetragonal (bct) structure in three dimensions. These transitions are the flow analogs of the martensitic transformations occurring in metals due to the stresses induced by a rapid quench. In hard-disk structures, using the bond-orientational analysis we show the presence of fourfold order. In sheared inelastic hard-sphere structures, even though the global bond-orientational analysis shows that the system is highly ordered, a third-order rotational invariant analysis shows that only about 40% of the spheres have face-centered-cubic (fcc) order, even in the dense and near-elastic limits, clearly indicating the coexistence of multiple crystalline orders. When layers of close-packed spheres slide past each other, in addition to the bct structure, the hexagonal-close-packed (hcp) structure is formed due to the random stacking faults. Using the Honeycutt-Andersen pair analysis and an analysis based on the 14-faceted polyhedra having six quadrilateral and eight hexagonal faces, we show the presence of bct and hcp signatures in shear ordered inelastic hard-spheres. Thus, our analysis shows that the dense sheared inelastic hard-spheres have a mixture of fcc, bct, and hcp structures.

Senthil Kumar, V.; Kumaran, V.

2006-05-01

257

Characterization of nano-wear mechanisms of hard disk coatings  

NASA Astrophysics Data System (ADS)

The wear mechanisms of carbon coated computer hard disks with laser-textured (LT) and mechanically-textured (MT) surfaces were characterized after contact start/stop (CSS) cyclic tests. Various analytical and mechanical testing techniques were employed to study the changes in topography, roughness, chemical elements, mechanical properties, and friction characteristics of the coating and lubricant. These techniques include: the atomic force microscopy (AFM), continuous nano-indentation test, nano-scratch test, time-of-flight secondary ion mass spectroscopy (TOF-SIMS), and Auger electron spectroscopy (AES). The CSS test at 15 k cycles resulted in tangible reductions of surface roughness of approximately 3.0 nm and 5.8 nm, respectively, for the LT bump and MT zone. The elastic modulus and hardness values increased after the CSS test, indicating strain hardening of the top coating layer. A critical load was identified for adhesion failure between the magnetic layer and the Ni-P layer. The TOF-SIMS analysis also revealed reductions in the intensities of all lubricant elements, indicating wear of the lubricant applied on the disk surface. All foregoing results confirm the usefulness of the characterization techniques employed to detect the subtle changes in disk surface characteristics.

Kim, Woo Seok; Kim, Jang-Kyo; Hwang, Pyung

2001-05-01

258

Nonequilibrium thermodynamics in sheared hard-sphere materials.  

PubMed

We combine the shear-transformation-zone (STZ) theory of amorphous plasticity with Edwards' statistical theory of granular materials to describe shear flow in a disordered system of thermalized hard spheres. The equations of motion for this system are developed within a statistical thermodynamic framework analogous to that which has been used in the analysis of molecular glasses. For hard spheres, the system volume V replaces the internal energy U as a function of entropy S in conventional statistical mechanics. In place of the effective temperature, the compactivity X=?V/?S characterizes the internal state of disorder. We derive the STZ equations of motion for a granular material accordingly, and predict the strain rate as a function of the ratio of the shear stress to the pressure for different values of a dimensionless, temperature-like variable near a jamming transition. We use a simplified version of our theory to interpret numerical simulations by Haxton, Schmiedeberg, and Liu, and in this way are able to obtain useful insights about internal rate factors and relations between jamming and glass transitions. PMID:23005087

Lieou, Charles K C; Langer, J S

2012-06-19

259

Hard-on-Hard Lubrication in the Artificial Hip under Dynamic Loading Conditions  

PubMed Central

The tribological performance of an artificial hip joint has a particularly strong influence on its success. The principle causes for failure are adverse short- and long-term reactions to wear debris and high frictional torque in the case of poor lubrication that may cause loosening of the implant. Therefore, using experimental and theoretical approaches models have been developed to evaluate lubrication under standardized conditions. A steady-state numerical model has been extended with dynamic experimental data for hard-on-hard bearings used in total hip replacements to verify the tribological relevance of the ISO 14242-1 gait cycle in comparison to experimental data from the Orthoload database and instrumented gait analysis for three additional loading conditions: normal walking, climbing stairs and descending stairs. Ceramic-on-ceramic bearing partners show superior lubrication potential compared to hard-on-hard bearings that work with at least one articulating metal component. Lubrication regimes during the investigated activities are shown to strongly depend on the kinematics and loading conditions. The outcome from the ISO gait is not fully confirmed by the normal walking data and more challenging conditions show evidence of inferior lubrication. These findings may help to explain the differences between the in vitro predictions using the ISO gait cycle and the clinical outcome of some hard-on-hard bearings, e.g., using metal-on-metal.

Sonntag, Robert; Reinders, Jorn; Rieger, Johannes S.; Heitzmann, Daniel W. W.; Kretzer, J. Philippe

2013-01-01

260

Dimensional crossover of hard parallel cylinders confined on cylindrical surfaces  

NASA Astrophysics Data System (ADS)

We derive, from the dimensional-crossover criterion, a fundamental-measure density functional for parallel hard curved rectangles moving on a cylindrical surface. We derive it from the density functional of circular arcs of length ? with centers of mass located on an external circumference of radius R0. The latter functional in turn is obtained from the corresponding two-dimensional functional for a fluid of hard disks of radius R on a flat surface with centers of mass confined onto a circumference of radius R0. Thus the curved length of closest approach between the two centers of mass of hard disks on this circumference is ?=2R0sin-1(R/R0), the length of the circular arcs. From the density functional of circular arcs, and by applying a dimensional expansion procedure to the spatial dimension orthogonal to the plane of the circumference, we finally obtain the density functional of curved rectangles of edge lengths ? and L. Along with the derivation, we show that, when the centers of mass of the disks are confined to the exterior circumference of a circle of radius R0, (i) for R0>R, the exact Percus one-dimensional (1D) density functional of circular arcs of length 2R0sin-1(R/R0) is obtained, and (ii) for R0R, the obtained functional is equivalent to that of parallel hard rectangles on a flat surface of the same lengths, except that now the density profile of curved rectangles is a periodic function of the azimuthal angle, ?(?,z)=?(?+2?,z). The phase behavior of a fluid of aligned curved rectangles is obtained by calculating the free-energy branches of smectic, columnar, and crystalline phases for different values of the ratio R0/R in the range 1

Martínez-Ratón, Yuri; Velasco, Enrique

2013-05-01

261

Dimensional crossover of hard parallel cylinders confined on cylindrical surfaces.  

PubMed

We derive, from the dimensional-crossover criterion, a fundamental-measure density functional for parallel hard curved rectangles moving on a cylindrical surface. We derive it from the density functional of circular arcs of length ? with centers of mass located on an external circumference of radius R(0). The latter functional in turn is obtained from the corresponding two-dimensional functional for a fluid of hard disks of radius R on a flat surface with centers of mass confined onto a circumference of radius R(0). Thus the curved length of closest approach between the two centers of mass of hard disks on this circumference is ?=2R(0)sin(-1)(R/R(0)), the length of the circular arcs. From the density functional of circular arcs, and by applying a dimensional expansion procedure to the spatial dimension orthogonal to the plane of the circumference, we finally obtain the density functional of curved rectangles of edge lengths ? and L. Along with the derivation, we show that, when the centers of mass of the disks are confined to the exterior circumference of a circle of radius R(0),(i) for R(0)>R, the exact Percus one-dimensional (1D) density functional of circular arcs of length 2R(0)sin(-1)(R/R(0)) is obtained, and (ii) for R(0)R, the obtained functional is equivalent to that of parallel hard rectangles on a flat surface of the same lengths, except that now the density profile of curved rectangles is a periodic function of the azimuthal angle, ?(?,z)=?(?+2?,z). The phase behavior of a fluid of aligned curved rectangles is obtained by calculating the free-energy branches of smectic, columnar, and crystalline phases for different values of the ratio R(0)/R in the range 1

Martínez-Ratón, Yuri; Velasco, Enrique

2013-05-31

262

Influence of polymerization time and depth of cure of resin composites determined by Vickers hardness  

PubMed Central

Background: Adequate polymerization of resin composites could be considered as a crucial factor in obtaining good clinical performance, particularly in stress-bearing areas. An insufficient curing degree affects the resin composite's chemical properties The current in vitro study evaluated the influence of polymerization time and depth of cure of six commercial resin composites by Vickers microhardness (VK). Materials and Methods: Six resin composites were selected: Three microhybrid (Esthet.X HD, Amaris, Filtek Silorane), two nanohybrid (Grandio, Ceram.X mono), and one nanofilled (Filtek Supreme XT). The VK of the surface was determined by a microhardness tester using a Vickers diamond indenter and a 200 g load applied for 15 s. The bottom to top mean VK ratio was calculated using the formula: Hardness ratio = VK of bottom surface/VK of top surface. Vickers hardness values of test materials during exposure time of 20 and 40 s and depths of cure of 2 and 3 mm were determined and compared. Data were analyzed using analysis of variance (ANOVA) test. Results: For all the tested materials and with all the exposure time periods, hardness ratio was higher than the minimum value indicated in literature (0.8). Exposure time and depth of cure did not affect hardness ratio values for Filtek Silorane, Grandio, and Filtek Supreme XT. Conclusion: Among the materials tested, the nanofilled and the nanohybrid resin composites were rather insensible to thickness variations. Miicrohybrid composites, instead, had features different from one another.

Lombardini, Marco; Chiesa, Marco; Scribante, Andrea; Colombo, Marco; Poggio, Claudio

2012-01-01

263

A survey for hard spectrum Rosat sources  

NASA Astrophysics Data System (ADS)

We have performed a survey of 188 Rosat fields looking for sources significantly harder than the X-ray background (?~0.5), with the aim of understanding the nature of sources that produce its remaining unresolved fraction. Our sample of 147 hard sources has a steeper-than-Euclidean log N-log S. We have spectroscopic identifications for 62 of the hard sources: 28 are broad line AGN, 12 are narrow emission line galaxies, and the remainder are galaxies without emission lines, clusters of galaxies, and Galactic stars. The properties of these sources are discussed. Contrary to currently favored theories for the production of the X-ray background, we do not find a single example of a high redshift type 2 QSO. .

Page, M. J.; Mittaz, J. P. D.; Carrera, F. J.

2001-12-01

264

Soft contributions to hard pion photoproduction  

SciTech Connect

Hard, or high transverse momentum, pion photoproduction can be a tool for probing the parton structure of the beam and target. The authors estimate the soft contributions to this process, with an eye toward delineating the region where perturbatively calculable processes dominate. Their soft process estimate is based on vector meson dominance and data based parameterizations of semiexclusive hadronic cross sections. They find that soft processes dominate in single pion photoproduction somewhat past 2 GeV transverse momentum at a few times 10 GeV incoming energy. The recent polarization asymmetry data is consistent with the perturbative asymmetry being diluted by polarization insensitive soft processes. Determining the polarized gluon distribution using hard pion photoproduction appears feasible with a few hundred GeV incoming energy (in the target rest frame).

Andrei Afanasev; Carl E. Carlson; Christian Wahlquist

1999-03-01

265

Soft contributions to hard pion photoproduction  

SciTech Connect

Hard, or high transverse momentum, pion photoproduction can be a tool for probing the parton structure of the beam and target. We estimate the soft contributions to this process, with an eye toward delineating the region where perturbatively calculable processes dominate. Our soft process estimate is based on vector meson dominance and data based parametrizations of semiexclusive hadronic cross sections. We find that soft processes dominate in single pion photoproduction somewhat past 2 GeV transverse momentum at a few times 10 GeV incoming energy. The recent polarization asymmetry data are consistent with the perturbative asymmetry being diluted by polarization insensitive soft processes. Determining the polarized gluon distribution using hard pion photoproduction appears feasible with a few hundred GeV of incoming energy (in the target rest frame). (c) 2000 The American Physical Society.

Afanasev, Andrei [Department of Physics, North Carolina Central University, Durham, North Carolina 27707 (United States); Thomas Jefferson National Accelerator Facility, 12000 Jefferson Avenue, Newport News, Virginia 23606 (United States); Carlson, Carl E. [Nuclear and Particle Theory Group, Physics Department, College of William and Mary, Williamsburg, Virginia 23187-8795 (United States); Wahlquist, Christian [Nuclear and Particle Theory Group, Physics Department, College of William and Mary, Williamsburg, Virginia 23187-8795 (United States)

2000-02-01

266

The hard-disk melting transition  

NASA Astrophysics Data System (ADS)

Melting in two spatial dimensions, as realized in thin films or at interfaces, represents one of the most fascinating phase transitions in nature, but it remains poorly understood. Even for the fundamental hard-disk model, the melting mechanism has not been agreed upon after 50 years of studies. A recent Monte Carlo algorithm [1] allows us to thermalize systems large enough to access the thermodynamic regime. I will show that melting in hard disks proceeds in two steps with a liquid phase, a hexatic phase, and a solid. The hexatic-solid transition is continuous while, surprisingly, the liquid-hexatic transition is of first order [2]. This melting scenario solves one of the fundamental statistical-physics models, which is at the root of a large body of theoretical, computational, and experimental research. 1. Bernard, E. P.; Krauth, W. & Wilson, D. B. Phys. Rev. E., 2009, 80, 056704 2. Bernard, E. P. & Krauth, W. Phys. Rev. Lett., 2011, 107, 155704

Bernard, Etienne; Krauth, Werner

2012-02-01

267

Demosaicing: heterogeneity-projection hard-decision adaptive interpolation using spectral-spatial correlation  

NASA Astrophysics Data System (ADS)

A novel heterogeneity-projection hard-decision adaptive interpolation (HPHD-AI) algorithm is proposed in this paper for color reproduction from Bayer mosaic images. The proposed algorithm aims to estimate the optimal interpolation direction and perform hard-decision interpolation, in which the decision is made before interpolation. To do so, a new heterogeneity-projection scheme based on spectral-spatial correlation is proposed to decide the best interpolation direction from the original mosaic image directly. Exploiting the proposed heterogeneity-projection scheme, a hard-decision rule can be designed easily to perform the interpolation. We have compared this technique with three recently proposed demosaicing techniques: Lu's, Gunturk's and Li's methods, by utilizing twenty-five natural images from Kodak PhotoCD. The experimental results show that HPHD-AI outperforms all of them in both PSNR values and S-CIELab ??*ab measures.

Tsai, Chi-Yi; Song, Kai-Tai

2006-02-01

268

Redox and Lewis acid-base activities through an electronegativity-hardness landscape diagram.  

PubMed

Chemistry is the science of bond making and bond breaking which requires redistribution of electron density among the reactant partners. Accordingly acid-base and redox reactions form cardinal components in all branches of chemistry, e.g., inorganic, organic, physical or biochemistry. That is the reason it forms an integral part of the undergraduate curriculum all throughout the globe. In an electronegativity (?)- hardness (?) landscape diagram the diagonal ??=?? line separates reducing agents from oxidizing agents as well as Lewis acids from Lewis bases. While electronegativity is related to the degree of electron transfer between two reactants, hardness is related to the resistance to that process. Accordingly the electronegativities of oxidizing agents/Lewis acids are generally greater than the corresponding hardness values and the reverse is true for reducing agents/Lewis bases. Electrophiles and nucleophiles are also expected to follow similar trends. PMID:24043544

Das, Ranjita; Vigneresse, Jean-Louis; Chattaraj, Pratim Kumar

2013-09-17

269

Phase transition, equation of state, and limiting shear viscosities of hard sphere dispersions  

NASA Astrophysics Data System (ADS)

Despite an interparticle potential consisting of only an infinite repulsion at contact, the thermodynamics and dynamics of concentrated dispersions of hard spheres are not yet fully understood. Colloidal poly-(methyl methacrylate) spheres with a grafted layer of poly-(12-hydroxy stearic acid) (PMMA-PHSA) comprise a common model for investigating structural, dynamic, and rheological properties. These highly monodisperse spheres can be index matched in nonaqueous solvents, reducing van der Waals forces and allowing characterization via light scattering. In this work, we test the behavior of these dispersions against expectations for hard spheres through observations of the phase behavior, x-ray densitometry of equilibrium sediments, and Zimm viscometry. We set the effective hard sphere volume fraction by the disorder-order transition, thereby accounting for the polymer layer, any swelling due to the solvent, and polydispersity. The melting transition then occurs close to the expected value and the equation of state for the fluid phase, extracted from the equilibrium sediment with x-ray densitometry, conforms to the Carnahan-Starling equation. However, the osmotic pressure of the crystalline phase lies slightly above that calculated for a single fcc crystal even after accounting for polydispersity. Likewise the high shear viscosity of the fluid compares well with other hard sphere dispersions, but the low shear viscosity for PMMA-PHSA hard spheres exceeds those for polystyrene and silica hard spheres, e.g., a relative viscosity of 45+/-3 at ?=0.50 rather than 24. Our low shear viscosities are consistent with other PMMA-PHSA data after rescaling for both the polymer layer thickness and polydispersity, and may represent the true hard sphere curve. We anticipate that the equation of state for the crystal deviates due to polycrystallinity or a direct effect of polydispersity.

Phan, See-Eng; Russel, William B.; Cheng, Zhengdong; Zhu, Jixiang; Chaikin, Paul M.; Dunsmuir, John H.; Ottewill, Ronald H.

1996-12-01

270

Dynamic hardness tester and cure meter  

NASA Astrophysics Data System (ADS)

The Shore hardness tester is used extensively throughout industry to determine the static modulus of materials. The new apparatus described here extends the capability of an indentor-type tester into the dynamic regime, and provides a measurement of the dynamic shear or Young's modulus and loss factor as a function of frequency. The instrument, model and data of typical rubber samples are given and compared to other dynamic measurements.

Madigosky, Walter M.; Fiorito, Ralph B.

1993-02-01

271

Hard tissue barrier formation after pulp capping?  

Microsoft Academic Search

Data sourcesSearches for relevant studies were made using Medline and the Cochrane Controlled Trials Register (CENTRAL). Reference lists of identified articles were searched.Study selectionStudies selected were those carried out on human teeth, with or without caries, that were treated using a pulp-capping procedure and where the hard tissue and pulp were analysed with the aid of a microscope. Reviews of

Lynnsey E Crane

2006-01-01

272

Hard metal pneumoconiosis with spontaneous bilateral pneumothorax.  

PubMed

Hard metal pneumoconiosis, first described in 1964, is a diffuse disease caused by the inhalation of cobalt particles. The disease can manifest as occupational asthma, interstitial disease or allergic alveolitis. We report the case of a young male, working as a tool sharpener, who presented with dry cough and progressive dyspnea for one year, as well as with spontaneous bilateral pneumothorax at admission. The diagnosis was confirmed by open lung biopsy. PMID:20209319

Moreira, Maria Auxiliadora Carmo; Cardoso, Amanda da Rocha Oliveira; Silva, Daniela Graner Schuwartz Tannus; Queiroz, Maria Conceição de Castro Antonelli Monteiro de; Oliveira, Albino Alegro; Noleto, Tiago Marinho Almeida

273

Viscosity coefficients of nematic hard particle fluids  

NASA Astrophysics Data System (ADS)

Enskog kinetic theory is applied to the calculation of the Miesowicz viscosities and the Leslie coefficients of a nematic liquid crystal comprised of hard ellipsoidal particles. The anisotropies in the calculated viscosities are consistent with those derived from computer simulation, affine transformation theory and from experiment. When the Miesowicz viscosities are combined with the diffusion coefficients for a nematic, approximate Stokes-Einstein relations are found.

Evans, Glenn T.

1998-01-01

274

Structure of crystals of hard colloidal spheres  

SciTech Connect

We report light-scattering measurements of powder diffraction patterns of crystals of essentially hard colloidal spheres. These are consistent with structures formed by stacking close-packed planes of particles in a sequence of permitted lateral positions, {ital A},{ital B},{ital C}, which shows a high degree of randomness. Crystals grown slowly, while still containing many stacking faults, show a tendency towards face-centered-cubic packing: possible explanations for this observation are discussed.

Pusey, P.N.; van Megen, W.; Bartlett, P.; Ackerson, B.J.; Rarity, J.G.; Underwood, S.M. (Royal Signals and Radar Establishment, Malvern, WR14 3PS, United Kingsom (GB) Department of Applied Physics, Royal Melbourne Institute of Technology, Melbourne, Victoria, Australia School of Chemistry, Bristol University, Bristol, BS8 1TS, United Kingdom Department of Physics, Oklahoma State University, Stillwater, Oklahoma 74078)

1989-12-18

275

Structure of crystals of hard colloidal spheres  

Microsoft Academic Search

We report light-scattering measurements of powder diffraction patterns of crystals of essentially hard colloidal spheres. These are consistent with structures formed by stacking close-packed planes of particles in a sequence of permitted lateral positions, {ital A},{ital B},{ital C}, which shows a high degree of randomness. Crystals grown slowly, while still containing many stacking faults, show a tendency towards face-centered-cubic packing:

P. N. Pusey; W. van Megen; P. Bartlett; B. J. Ackerson; J. G. Rarity; S. M. Underwood

1989-01-01

276

Structure of crystals of hard colloidal spheres  

Microsoft Academic Search

We report light-scattering measurements of powder diffraction patterns of crystals of essentially hard colloidal spheres. These are consistent with structures formed by stacking close-packed planes of particles in a sequence of permitted lateral positions, A,B,C, which shows a high degree of randomness. Crystals grown slowly, while still containing many stacking faults, show a tendency towards face-centered-cubic packing: possible explanations for

P. N. Pusey; W. van Megen; P. Bartlett; B. J. Ackerson; J. G. Rarity; S. M. Underwood

1989-01-01

277

Diamond growth on hard carbon films  

Microsoft Academic Search

A three-step process for enhancing the nucleation density of diamond on unscratched silicon substrates using microwave-plasma-enhanced chemical vapor deposition is described. Hard diamond-like carbon (dlc) films with thickness in the range 5–100 nm were first formed on smooth (100) silicon surfaces using a vacuum-arc plasma deposition technique at room temperature. The dlc-coated silicon substrates were subsequently subjected to a low-temperature

Z. Feng; S. Anders; A. Anders; J AGERIII; I. G. Brown; K. Komvopoulos; D. B. Bogy

1996-01-01

278

Nuclear hardness assurance for aeronautical systems  

Microsoft Academic Search

Nuclear hardness assurance for aircraft and airborne systems is considered from the point of view of an affordable research program's formulation and management prior to systems acquisitions. Among the threats to aircraft primary and secondary structures, flight crews, and electronics are: (1) blast overpressures of 1-3 psi for a 1 megaton blast, (2) blast-generated gusts of 75-100 ft\\/sec, (3) thermal

R. P. Patrick; J. M. Ferry

1980-01-01

279

Magnified hard X-ray microtomography  

Microsoft Academic Search

Summary form only given. In the field of hard X-ray microtomography one goal is the enhancement of resolution. Several ways can be followed to obtain this objective. One possibility is the use of high-resolution X-ray films or detector screens coupled with a microscope optical system. The limitation of resolution is either given by the grain size of the X-ray film

C. Rau; T. Weitkamp; A. Snigirev; C. G. Schroer; J. Tummler; B. Lengeler

2000-01-01

280

Effective isotropic potential for dipolar hard spheres.  

PubMed

A new effective isotropic potential is proposed for the dipolar hard-sphere fluid, on the basis of recent results by others for its angle-averaged radial distribution function. The new effective potential is shown to exhibit oscillations even for moderately high densities and moderately strong dipole moments, which are absent from earlier effective isotropic potentials. The validity and significance of this result are briefly discussed. PMID:23552475

Teixeira, P I C

2013-04-03

281

Hard and soft osteo-arthritis  

PubMed Central

This short paper attempts to show how the X-ray appearance influences the choice and success of operative procedures performed on the hip and knee joints for osteo-arthritis. If the bones look ‘soft’ the only methods likely to succeed are those in which total replacement coupled with the use of cement ensure firm anchorage and wide distribution of stress. When bones look ‘hard’ simpler methods are usually satisfactory. ImagesFig. 1Fig. 2

Broad, C. P.

1968-01-01

282

Is cannabis a gateway to hard drugs?  

Microsoft Academic Search

The gateway hypothesis proposes that use of cannabis directly increases the risk of consuming hard drugs. We test this controversial,\\u000a but influential, hypothesis on a sample of cannabis users, exploiting a unique set of drug price data. A flexible approach\\u000a is developed to identify the causal gateway effect using a bivariate survival model with shared frailty estimated using a\\u000a latent

Hans Olav Melberg; Andrew M. Jones; Anne Line Bretteville-Jensen

2010-01-01

283

Hard spheres on the gyroid surface.  

PubMed

We find that 48/64 hard spheres per unit cell on the gyroid minimal surface are entropically self-organized. Striking evidence is obtained in terms of the acceptance ratio of Monte Carlo moves and order parameters. The regular tessellations of the spheres can be viewed as hyperbolic tilings on the Poincaré disc with a negative Gaussian curvature, one of which is, equivalently, the arrangement of angels and devils in Escher's Circle Limit IV. PMID:24098841

Dotera, Tomonari; Kimoto, Masakiyo; Matsuzawa, Junichi

2012-01-18

284

Hard spheres on the gyroid surface  

PubMed Central

We find that 48/64 hard spheres per unit cell on the gyroid minimal surface are entropically self-organized. Striking evidence is obtained in terms of the acceptance ratio of Monte Carlo moves and order parameters. The regular tessellations of the spheres can be viewed as hyperbolic tilings on the Poincaré disc with a negative Gaussian curvature, one of which is, equivalently, the arrangement of angels and devils in Escher's Circle Limit IV.

Dotera, Tomonari; Kimoto, Masakiyo; Matsuzawa, Junichi

2012-01-01

285

Non-Conventional Tungsten-Base Hard Metal.  

National Technical Information Service (NTIS)

A novel hard-metal composition comprising borides and carbides of tungsten, nickel, and iron is made by reaction hot pressing mixtures of elemental tungsten, nickel, and iron powders with small quantities of boron carbide. The hardness of these compositio...

H. Sheinberg

1981-01-01

286

Shock waves in dense hard disk fluids  

NASA Astrophysics Data System (ADS)

Media composed of colliding hard disks (2D) or hard spheres (3D) serve as good approximations for the collective hydrodynamic description of gases, liquids and granular media. In the present study, the compressible hydrodynamics and shock dynamics are studied for a two-dimensional hard-disk medium at both the continuum and discrete particle level descriptions. For the continuum description, closed form analytical expressions for the inviscid hydrodynamic description, shock Hugoniot, isentropic exponent and shock jump conditions were obtained using the Helfand equation of state. The closed-form analytical solutions permitted us to gain physical insight into the role of the material's density on its compressibility, i.e. how the medium compresses under mechanical loadings and sustains wave motion. Furthermore, the predictions were found in excellent agreement with calculations using the event driven molecular dynamics method involving 30,000 particles over the entire range of compressibility spanning the dilute ideal gas and liquid phases. In all cases, it was found that the energy imparted by the piston motion to the thermalized medium behind the propagating shock was quasi-independent of the medium's packing fraction, with a correction vanishing with increasing shock Mach numbers.

Sirmas, N.; Tudorache, M.; Barahona, J.; Radulescu, M. I.

2012-05-01

287

Microscopic dynamics of thin hard rods.  

PubMed

We analyze the microscopic dynamics and transport properties of a gas of thin hard rods. Based on the collision rules for hard needles we derive a hydrodynamic equation that determines the coupled translational and rotational dynamics of a tagged thin rod in an ensemble of identical rods. Specifically, based on a pseudo-Liouville operator for binary collisions between rods, the Mori-Zwanzig projection formalism is used to derive a continued fraction representation for the correlation function of the tagged particle's density, specifying its position and orientation. Truncation of the continued fraction gives rise to a generalized Enskog equation, which can be compared to the phenomenological Perrin equation for anisotropic diffusion. Only for sufficiently large density do we observe anisotropic diffusion, as indicated by an anisotropic mean-square displacement, growing linearly with time. For lower densities, the Perrin equation is shown to be an insufficient hydrodynamic description for hard needles interacting via binary collisions. We compare our results to simulations and find excellent quantitative agreement for low densities and qualitative agreement for higher densities. PMID:16674265

Otto, Matthias; Aspelmeier, Timo; Zippelius, Annette

2006-04-21

288

Size dependent hardness of silver single crystals  

NASA Astrophysics Data System (ADS)

The hardness of thick, high-purity, epitaxially grown silver on sodium chloride is found to be dependent on the size of the indentation for sizes below approximately 10 micron. The measurement of the size effect has been made in two ways. In one, the hardness has been calculated from the load-displacement curve obtained from an instrumented microhardness testing machine and assuming a geometric self-similarity in the indenter shape. In the other measurement, the hardness was obtained from the load exerted by the microhardness tester divided by the indentation impression area as measured by atomic force microscopy. The observed variation in microhardness with indentation size is consistent with a simplified strain gradient plasticity model in which the densities of the geometrically necessary and statistically stored dislocations are fitting parameters. An equally good fit can also be made with a simple geometric scaling relationship. Transmission electron microscopy observations of a thin (approximately 50 nm) epitaxial gold film embedded in the silver layers revealed that the deformation was primarily restricted to the sharp edges of the indentation. In addition, deformation twinning within the indentation impression was observed on the /111/ planes.

Ma, Qing; Clarke, David R.

1995-04-01

289

Hard X-ray Microscopic Images of the Human Hair  

SciTech Connect

The better visualization of the human organs or internal structure is challenging to the physicist and physicians. It can lead to more understanding of the morphology, pathophysiology and the diagnosis. Conventionally used methods to investigate cells or architectures, show limited value due to sample processing procedures and lower resolution. In this respect, Zernike type phase contrast hard x-ray microscopy using 6.95keV photon energy has advantages. We investigated hair fibers of the normal healthy persons. Coherence based phase contrast images revealed three distinct structures of hair, medulla, cortex, and cuticular layer. Some different detailed characters of each sample were noted. And further details would be shown and these results would be utilized as basic data of morphologic study of human hair.

Goo, Jawoong; Jeon, Soo Young; Oh, Tak Heon; Hong, Seung Phil; Lee, Won-Soo [Department of Dermatology and Institute of Hair and Cosmetic Medicine, Yonsei University Wonju College of Medicine, Wonju (Korea, Republic of); Yon, Hwa Shik [Pohang Accelerator Laboratory, Pohang University of Science and Technology, Pohang (Korea, Republic of)

2007-01-19

290

Hard X-ray Microscopic Images of the Human Hair  

NASA Astrophysics Data System (ADS)

The better visualization of the human organs or internal structure is challenging to the physicist and physicians. It can lead to more understanding of the morphology, pathophysiology and the diagnosis. Conventionally used methods to investigate cells or architectures, show limited value due to sample processing procedures and lower resolution. In this respect, Zernike type phase contrast hard x-ray microscopy using 6.95keV photon energy has advantages. We investigated hair fibers of the normal healthy persons. Coherence based phase contrast images revealed three distinct structures of hair, medulla, cortex, and cuticular layer. Some different detailed characters of each sample were noted. And further details would be shown and these results would be utilized as basic data of morphologic study of human hair.

Goo, Jawoong; Jeon, Soo Young; Oh, Tak Heon; Hong, Seung Phil; Yon, Hwa Shik; Lee, Won-Soo

2007-01-01

291

New York Sea Grant's Hard Clam Research Initiative  

NSDL National Science Digital Library

This New York Sea Grant website hosts the Hard Clam Research Initiative, a program launched in October 1999 to investigate the population dynamics of hard clams in Long Island's south shore estuary. The site features links to program information, the research projects involved, facts about hard clams and the hard clam industry, a list of publications, media links, and contact information. It also includes a "What's New" column that highlights current events associated with the project.

Focazio, Paul C.; Grant, New Y.

292

Chronic toxicity of chloride to freshwater species: effects of hardness and implications for water quality guidelines.  

PubMed

Toxicity tests using nine freshwater species (Ceriodaphnia dubia, Daphnia magna, Oncorhynchus mykiss, Pimephales promelas, Lumbriculus variegatus, Tubifex tubifex, Chironomus dilutus, Hyallela azteca, and Brachionus calyciflorus) were conducted to evaluate their sensitivity to chloride. Acute-to-chronic ratios (ACRs) from these tests indicate the ACR of 7.59 employed by the United States Environmental Protection Agency (U.S. EPA) in deriving its water quality guideline for chloride may be conservative; a revised ACR of 3.50 is presented here. The endpoints used to calculate the ACR included 24-h to 96-h median lethal concentrations (LC50s) for acute tests, and 48-h to 54-d inhibition concentration (ICx) values for growth or reproduction for chronic exposures. Data from the present chronic toxicity tests, and other investigators, were used to propose a water quality guideline for long-term exposure to chloride using a species sensitivity distribution (SSD) approach. The 5th percentile from the SSD was calculated as 307?mg/L and proposed as the water quality guideline. Cladocerans were the most sensitive species in the dataset. Ceriodaphnia dubia was used to evaluate the relationship between water hardness and sensitivity to chloride. A strong relationship was observed and was used to establish a hardness-related equation to modify the proposed water quality guideline on the basis of water hardness, resulting in values ranging from 64?mg/L chloride at 10?mg/L hardness to 388?mg/L chloride at 160?mg/L hardness (as CaCO?). These data suggest that current water quality guidelines for chloride may be overly conservative in water with moderate-to-high hardness, and may not be sufficiently protective under soft-water conditions. PMID:20872898

Elphick, James R F; Bergh, Kelli D; Bailey, Howard C

2011-01-01

293

Runaway electron energy measurement using hard x-ray spectroscopy in 'Damavand' tokamak  

SciTech Connect

Set of experiments has been developed to study existing runaway electrons in ''Damavand'' tokamak plasma upon characteristics of hard x-ray emissions produced by collision of the runaway electrons with the plasma particles and limiters. As a first step, spatial distribution of hard x-ray emissions on the equatorial plane of the torus was considered. Obtained spectra of hard x-ray emissions for different alignments of shielded detector indicate isotropic emissivity in the equatorial plane. This is in agreement with wide angle cone of bremsstrahlung radiations, deduced from the mean value of energy of the runaway electrons. The mean energy was calculated from the slope of the energy spectrum of hard x-ray photons. In the second stage in order to investigate time evolution of energy of the runaway electrons, similar technique were applied to obtain hard x-ray energy in every 3 ms intervals, from the beginning to the end of plasma. The mean energy of the runaway electrons increases during the ramp up phase and reaches its maximum between 3 and 9 ms after plasma formation. Also considering the time dependence of the counted photons in each energy range shows that energetic photons are emitted during the ramp up phase of the plasma current in Damavand tokamak.

Rasouli, C.; Farahbod, A. H.; Rasouli, H.; Lamehi, M. [School of Plasma Physics and Nuclear Fusion, Institute of Nuclear Science and Technology, AEOI, P.O. Box 14155-1339, Tehran (Iran, Islamic Republic of); Iraji, D. [Centre de Recherches en Physique des Plasmas, Association EURATOM-Confederation Suisse, Ecole Polytechnique Federale de Lausanne, CH-1015 (Switzerland); Akhtari, K. [Department of Physics, Sharif University of Technology, P.O. Box 11365-9161, Tehran (Iran, Islamic Republic of); Modarresi, H. [Department of Mechanical Engineering, Sharif University of Technology, P.O. Box 11365-9567, Tehran (Iran, Islamic Republic of)

2009-01-15

294

Runaway electron energy measurement using hard x-ray spectroscopy in "Damavand" tokamak.  

PubMed

Set of experiments has been developed to study existing runaway electrons in "Damavand" tokamak plasma upon characteristics of hard x-ray emissions produced by collision of the runaway electrons with the plasma particles and limiters. As a first step, spatial distribution of hard x-ray emissions on the equatorial plane of the torus was considered. Obtained spectra of hard x-ray emissions for different alignments of shielded detector indicate isotropic emissivity in the equatorial plane. This is in agreement with wide angle cone of bremsstrahlung radiations, deduced from the mean value of energy of the runaway electrons. The mean energy was calculated from the slope of the energy spectrum of hard x-ray photons. In the second stage in order to investigate time evolution of energy of the runaway electrons, similar technique were applied to obtain hard x-ray energy in every 3 ms intervals, from the beginning to the end of plasma. The mean energy of the runaway electrons increases during the ramp up phase and reaches its maximum between 3 and 9 ms after plasma formation. Also considering the time dependence of the counted photons in each energy range shows that energetic photons are emitted during the ramp up phase of the plasma current in Damavand tokamak. PMID:19191433

Rasouli, C; Iraji, D; Farahbod, A H; Akhtari, K; Rasouli, H; Modarresi, H; Lamehi, M

2009-01-01

295

Effect of Austenitizing Heat Treatment on the Microstructure and Hardness of Martensitic Stainless Steel AISI 420  

NASA Astrophysics Data System (ADS)

The effect of austenitizing on the microstructure and hardness of two martensitic stainless steels was examined with the aim of supplying heat-treatment guidelines to the user that will ensure a martensitic structure with minimal retained austenite, evenly dispersed carbides and a hardness of between 610 and 740 HV (Vickers hardness) after quenching and tempering. The steels examined during the course of this examination conform in composition to medium-carbon AISI 420 martensitic stainless steel, except for the addition of 0.13% vanadium and 0.62% molybdenum to one of the alloys. Steel samples were austenitized at temperatures between 1000 and 1200 °C, followed by oil quenching. The as-quenched microstructures were found to range from almost fully martensitic structures to martensite with up to 35% retained austenite after quenching, with varying amounts of carbides. Optical and scanning electron microscopy was used to characterize the microstructures, and X-ray diffraction was employed to identify the carbide present in the as-quenched structures and to quantify the retained austenite contents. Hardness tests were performed to determine the effect of heat treatment on mechanical properties. As-quenched hardness values ranged from 700 to 270 HV, depending on the amount of retained austenite. Thermodynamic predictions (using the CALPHAD™ model) were employed to explain these microstructures based on the solubility of the carbide particles at various austenitizing temperatures.

Barlow, L. D.; Du Toit, M.

2012-07-01

296

Density functional theory for colloidal mixtures of hard platelets, rods, and spheres  

NASA Astrophysics Data System (ADS)

A geometry-based density-functional theory is presented for mixtures of hard spheres, hard needles, and hard platelets; both the needles and platelets are taken to be of vanishing thickness. Geometrical weight functions that are characteristic for each species are given, and it is shown how convolutions of pairs of weight functions recover each Mayer bond of the ternary mixture and hence ensure the correct second virial expansion of the excess free-energy functional. The case of sphere-platelet overlap relies on the same approximation as does Rosenfeld’s functional for strictly two-dimensional hard disks. We explicitly control contributions to the excess free energy that are of third order in density. Analytic expressions relevant for the application of the theory to states with planar translational and cylindrical rotational symmetry—e.g., to describe behavior at planar smooth walls—are given. For binary sphere-platelet mixtures, in the appropriate limit of small platelet densities, the theory differs from that used in a recent treatment [L. Harnau and S. Dietrich, Phys. Rev. E 71, 011504 (2004)]. As a test case of our approach we consider the isotropic-nematic bulk transition of pure hard platelets, which we find to be weakly first order, with values for the coexistence densities and the nematic order parameter that compare well with simulation results.

Esztermann, Ansgar; Reich, Hendrik; Schmidt, Matthias

2006-01-01

297

Aperiodic Task Scheduling for Hard Real-Time Systems  

Microsoft Academic Search

 A real-time system consists of both aperiodic and periodic tasks. Periodic tasks have regular arrival times and hard deadlines. Aperiodic tasks have irregular arrival times and either soft or hard deadlines. In this article, we present a new algorithm, the Sporadic Server algorithm, which greatly improves response times for soft deadline aperiodic tasks and can guarantee hard deadlines for both

Brinkley Sprunt; Lui Sha; John P. Lehoczky

1989-01-01

298

Hard metal lung disease in an oil industry worker.  

PubMed

Hard metal lung disease, which manifests as giant cell interstitial pneumonia, is caused by exposure to hard metal dust. We report the case of an oil industry worker diagnosed with hard metal lung disease. The diagnosis was based on the clinical, radiological and anatomopathological analysis, as well as on pulmonary function testing. PMID:20126930

Bezerra, Patrícia Nunes; Vasconcelos, Ana Giselle Alves; Cavalcante, Lílian Loureiro Albuquerque; Marques, Vanessa Beatriz de Vasconcelos; Nogueira, Teresa Neuma Albuquerque Gomes; Holanda, Marcelo Alcantara

2009-12-01

299

Geotechnical basis for underground energy storage in hard rock  

Microsoft Academic Search

Underground pumped hydroelectric storage requires the excavation of caverns in hard rock. Hard rock caverns, also, are one option for compressed air stoage. Preliminary design studies for both technologies at a specific site were completed. The geotechnical aspects of these storage systems are discussed from a generic viewpoint. Information about effective use of hard rock openings, including tunnels and shafts,

O. C. Farquhar

1982-01-01

300

Evaluation of Deloro Stellite Hard Facing Fuse Paste C.  

National Technical Information Service (NTIS)

An evaluation of Deloro Stellite hard facing fuse paste C has been carried out as part of an evaluation program of hard facing processes. It has been shown that a hard wear resistant surface can be successfully produced in one layer requiring no further t...

J. Smart B. S. Butler

1975-01-01

301

The ideal strength and mechanical hardness of solids  

Microsoft Academic Search

Relationships between intrinsic mechanical hardness and atomic-scale properties are reviewed. Hardness scales closely and linearly with shear modulus for a given class of material (covalent, ionic or metallic). A two-parameter fit and a Peierls-stress model produce a more universal scaling relationship, but no model can explain differences in hardness between the transition metal carbides and nitrides. Calculations of \\

Christopher Robert Krenn

2000-01-01

302

The hardness of decoding linear codes with preprocessing  

Microsoft Academic Search

Absfract -The problem of maximum likelihood decoding of linear block codes is known to be hard (3). It is shown that the problem remains hard even if the code is known in advance, and can be preprocessed for as long as desired in order to devise a decoding algorithm. The hardness is based on the fact that existence of a

Jehoshua Bruck; Moni Naor

1990-01-01

303

Easiness Assumptions and Hardness Tests: Trading Time for Zero Error  

Microsoft Academic Search

We propose a new approach toward derandomization in the uniform setting, where it is computationally hard to find possible mistakes in the simulation of a given probabilistic algorithm. The approach consists in combining both easiness and hardness complexity assumptions: if a derandomization method based on an easiness assumption fails, then we obtain a certain hardness test that can be used

Valentine Kabanets

2001-01-01

304

Future for Hard Fibers and Competition from Synthetics.  

National Technical Information Service (NTIS)

The world's hard-fibers economy, already in a period of crisis, faces an uncertain future. Severe pressure from synthetic substitutes threatens the very future of the hard-fibers industry. The paper examines the structure of the hard-fibers economy, as we...

E. R. Grilli

1975-01-01

305

RESEARCH NOTE Radial distribution functions of hard sphere mixtures  

Microsoft Academic Search

A simple method is proposed to determine radial distribution functions of pure hard sphere fluids and mixtures of hard spheres of different diameters. The range of centre-centre distances of a pair of hard spheres is divided into two parts: that from the closest approach up to the distance xm of the first minimum, and that for distances x > xm.

Tomas Boublik

1997-01-01

306

Surface Integrity of Hard Metal Parts Machined by WEDM  

Microsoft Academic Search

Hard metal is characterised by having a extremely high hardness and high wear resistance, and those characteristics make difficult conventional machining. Electrical Discharge Machining (EDM) has become an attractive and feasible method for the manufacturing of precision hard metal tooling, and it is now an alternative to classical diamond grinding. This is due to the thermal nature of material removal

S. Plaza; B. Izquierdo; J. A. Sanchez; N. Ortega; J. M. Ramos

2009-01-01

307

From Value Chain to Value Network  

Microsoft Academic Search

The concept of a value chain has assumed a dominant position in the strategic analysis of industries. However, the value chain is underpinned by a particular value creating logic and its application results in particular strategic postures. Adopting a network perspective provides an alternative perspective that is more suited to New Economy organisations, particularly for those where both the product

Anna Rylander

2006-01-01

308

Interfacial free energy of a hard-sphere fluid in contact with curved hard surfaces  

NASA Astrophysics Data System (ADS)

Using molecular-dynamics simulation, we have calculated the interfacial free energy ? between a hard-sphere fluid and hard spherical and cylindrical colloidal particles, as functions of the particle radius R and the fluid packing fraction ?=??3/6, where ? and ? are the number density and hard-sphere diameter, respectively. These results verify that Hadwiger's theorem from integral geometry, which predicts that ? for a fluid at a surface, with certain restrictions, should be a linear combination of the average mean and Gaussian surface curvatures, is valid within the precision of the calculation for spherical and cylindrical surfaces up to ??0.42. In addition, earlier results for ? for this system [Bryk , Phys. Rev. EPLEEE81539-375510.1103/PhysRevE.68.031602 68, 031602 (2003)] using a geometrically based classical density functional theory are in excellent agreement with the current simulation results for packing fractions in the range where Hadwiger's theorem is valid. However, above ??0.42, ?(R) shows significant deviations from the Hadwiger form indicating limitations to its use for high-density hard-sphere fluids. Using the results of this study together with Hadwiger's theorem allows one, in principle, to determine ? for any sufficiently smooth surface immersed in a hard-sphere fluid.

Laird, Brian B.; Hunter, Allie; Davidchack, Ruslan L.

2012-12-01

309

Development of method for evaluating cell hardness and correlation between bacterial spore hardness and durability  

PubMed Central

Background Despite the availability of conventional devices for making single-cell manipulations, determining the hardness of a single cell remains difficult. Here, we consider the cell to be a linear elastic body and apply Young’s modulus (modulus of elasticity), which is defined as the ratio of the repulsive force (stress) in response to the applied strain. In this new method, a scanning probe microscope (SPM) is operated with a cantilever in the “contact-and-push” mode, and the cantilever is applied to the cell surface over a set distance (applied strain). Results We determined the hardness of the following bacterial cells: Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and five Bacillus spp. In log phase, these strains had a similar Young’s modulus, but Bacillus spp. spores were significantly harder than the corresponding vegetative cells. There was a positive, linear correlation between the hardness of bacterial spores and heat or ultraviolet (UV) resistance. Conclusions Using this technique, the hardness of a single vegetative bacterial cell or spore could be determined based on Young’s modulus. As an application of this technique, we demonstrated that the hardness of individual bacterial spores was directly proportional to heat and UV resistance, which are the conventional measures of physical durability. This technique allows the rapid and direct determination of spore durability and provides a valuable and innovative method for the evaluation of physical properties in the field of microbiology.

2012-01-01

310

Interfacial free energy of a hard-sphere fluid in contact with curved hard surfaces.  

PubMed

Using molecular-dynamics simulation, we have calculated the interfacial free energy ? between a hard-sphere fluid and hard spherical and cylindrical colloidal particles, as functions of the particle radius R and the fluid packing fraction ?=??(3)/6, where ? and ? are the number density and hard-sphere diameter, respectively. These results verify that Hadwiger's theorem from integral geometry, which predicts that ? for a fluid at a surface, with certain restrictions, should be a linear combination of the average mean and Gaussian surface curvatures, is valid within the precision of the calculation for spherical and cylindrical surfaces up to ? ? 0.42. In addition, earlier results for ? for this system [Bryk et al., Phys. Rev. E 68, 031602 (2003)] using a geometrically based classical density functional theory are in excellent agreement with the current simulation results for packing fractions in the range where Hadwiger's theorem is valid. However, above ? ? 0.42, ?(R) shows significant deviations from the Hadwiger form indicating limitations to its use for high-density hard-sphere fluids. Using the results of this study together with Hadwiger's theorem allows one, in principle, to determine ? for any sufficiently smooth surface immersed in a hard-sphere fluid. PMID:23367884

Laird, Brian B; Hunter, Allie; Davidchack, Ruslan L

2012-12-20

311

Enacting objects for plant-wide HARD real-time online distributed control system (P-hard-RODCS): Oosim  

Microsoft Academic Search

Distributed control networks running in real-life industrial environments that can support the development of plant-wide hard real-time online distributed control system (P-hard-RODCS) are rare. Due to the lack of practicalities, traditional simulation method is not feasible for realistic utilization. The practicality of constructing object-oriented nodes to simulate the plant-wide HARD real-time online distributed control system (Oosim\\/P-hard-RODCS) is the main concern

N. C. Low; K. T. Ng

1993-01-01

312

Evaluation of degree of conversion and hardness of dental composites photo-activated with different light guide tips  

PubMed Central

Objective: The aim of this study was to evaluate the degree of conversion and hardness of different composite resins, photo-activated for 40 s with two different light guide tips, fiber optic and polymer. Methods: Five specimens were made for each group evaluated. The percentage of unreacted carbon double bonds (% C?C) was determined from the ratio of absorbance intensities of aliphatic C?C (peak at 1637 cm?1) against internal standard before and after curing of the specimen: aromatic C-C (peak at 1610 cm?1). The Vickers hardness measurements were performed in a universal testing machine. A 50 gf load was used and the indenter with a dwell time of 30 seconds. The degree of conversion and hardness mean values were analyzed separately by ANOVA and Tukey’s test, with a significance level set at 5%. Results: The mean values of degree of conversion for the polymer and fiber optic light guide tip were statistically different (P<.001). The hardness mean values were statistically different among the light guide tips (P<.001), but also there was difference between top and bottom surfaces (P<.001). Conclusions: The results showed that the resins photo-activated with the fiber optic light guide tip promoted higher values for degree of conversion and hardness.

Galvao, Marilia Regalado; Caldas, Sergei Godeiro Fernandes Rabelo; Bagnato, Vanderlei Salvador; de Souza Rastelli, Alessandra Nara; de Andrade, Marcelo Ferrarezi

2013-01-01

313

Turning values into valuation : Can corporate social responsibility survive hard times and emerge intact?  

Microsoft Academic Search

Purpose – This article aims to explore the recent evolution of corporate social responsibility (CSR) from fringe philosophy to corporate buzzword. Design\\/methodology\\/approach – For the period 2008 to mid-2009, the author surveyed articles in mainstream media and business periodicals focusing on corporate social responsibility; reviewed polls for methodology and results; searched press releases for mention of corporate social responsibility; and

Warren Strugatch

2011-01-01

314

Interactions between linear alkylbenzene sulfonates and water hardness ions. II. Reducing hardness sensitivity by the addition of micelle promotion agents  

Microsoft Academic Search

Agents which promote micellization of linear alkylbenzene sulfonates (LAS) improve LAS hard-water detergency performance by\\u000a reducing water hardness sensitivity. A model is proposed which correlates micellization and water hardness tolerance. The\\u000a ability of inorganic salts and cosurfactants to act as micelle promotion agents is discussed.

Michael F. Cox; K. Lee Matheson

1985-01-01

315

HARD-SOFT-HARD FLARE SPECTRA AND THEIR ENERGY DEPENDENCE IN SPECTRAL EVOLUTION OF A SOLAR HARD X-RAY FLARE  

SciTech Connect

In this Letter, we studied the time evolution of the energy-dependent spectral indices for the 2004 November 3 solar hard X-ray flare observed by RHESSI. The common soft-hard-soft (SHS) pattern spectra were found at the lower energies, while a new feature, hard-soft-hard (HSH), was found at higher energies for each subpeak. As the energy increases, the SHS pattern is gradually converted into the HSH pattern. Some possible explanations for the spectral evolution and its energy dependence are discussed, such as the return current.

Shao Chengwen; Huang Guangli [Purple Mountain Observatory, Chinese Academy of Sciences (CAS), Nanjing, 210008 (China)], E-mail: chengwenshao@yahoo.com.cn, E-mail: glhuang@pmo.ac.cn

2009-04-01

316

Evaluation of Vickers hardness and depth of cure of six composite resins photo-activated with different polymerization modes  

PubMed Central

Aim: The current in vitro study evaluated Vickers hardness (VK) and depth of cure (hardness ratio) of six resin composites, polymerized with a light-emitting diode (LED) curing unit by different polymerization modes: Standard 20 s, Standard 40 s, Soft-start 40 s. Materials and Methods: Six resin composites were selected for the present study: three microhybrid (Esthet.X HD, Amaris, Filtek Silorane), two nanohybrid (Grandio, Ceram.X mono) and one nanofilled (Filtek Supreme XT). The VK of the surface was determined with a microhardness tester using a Vickers diamond indenter and a 200 g load applied for 15 seconds. The mean VK and hardness ratio of the specimens were calculated using the formula: hardness ratio = VK of bottom surface / VK of top surface. Results: For all the materials tested and with all the polymerization modes, hardness ratio was higher than the minimum value indicated in literature in order to consider the bottom surface as adequately cured (0.80). Curing time did not affect hardness ratio values for Filtek Silorane, Grandio and Filtek Supreme XT. Conclusion: The effectiveness of cure at the top and bottom surface was not affected by Soft-start polymerization mode.

Poggio, C; Lombardini, M; Gaviati, S; Chiesa, M

2012-01-01

317

Fate of Mycobacterium avium subsp. paratuberculosis in Swiss Hard and Semihard Cheese Manufactured from Raw Milk  

PubMed Central

Raw milk was artificially contaminated with declumped cells of Mycobacterium avium subsp. paratuberculosis at a concentration of 104 to 105 CFU/ml and was used to manufacture model hard (Swiss Emmentaler) and semihard (Swiss Tisliter) cheese. Two different strains of M. avium subsp. paratuberculosis were tested, and for each strain, two model hard and semihard cheeses were produced. The survival of M. avium subsp. paratuberculosis cells was monitored over a ripening period of 120 days by plating out homogenized cheese samples onto 7H10-PANTA agar. In both the hard and the semihard cheeses, counts decreased steadily but slowly during cheese ripening. Nevertheless, viable cells could still be detected in 120-day cheese. D values were calculated at 27.8 days for hard and 45.5 days for semihard cheese. The most important factors responsible for the death of M. avium subsp. paratuberculosis in cheese were the temperatures applied during cheese manufacture and the low pH at the early stages of cheese ripening. Since the ripening period for these raw milk cheeses lasts at least 90 to 120 days, the D values found indicate that 103 to 104 cells of M. avium subsp. paratuberculosis per g will be inactivated.

Spahr, U.; Schafroth, K.

2001-01-01

318

Effects of professionally applied topical fluorides on surface hardness of composite-based restoratives.  

PubMed

This study investigated the effects of professionally applied topical fluorides on the surface hardness of a composite (Spectrum TPH), a compomer (DyractAP) and a giomer (Reactmer). Thirty specimens of each material were fabricated and stored in distilled water at 37 degrees C for one week. These specimens were then randomly divided into five groups of six and treated for 36 hours at 37 degrees C with one of the following: distilled water (control), 1.23% acidulated phosphate fluoride (APF) foam, 0.9% neutral foam, 1.23% APF gel and 0.4% stannous fluoride gel. The treated specimens were subsequently subjected to microhardness testing (load = 500 gf; dwell time = 15 seconds). Results were analyzed using ANOVA/Scheffe's test (p<0.05). The effects of topical fluoride application on surface hardness was material dependent. For all materials, treatment with APF gel and foam significantly reduced surface hardness when compared to the control. KHN values after exposure to APF gel were consistently the lowest and ranged from 4.53 to 15.97. Control KHN values were higher, ranging from 32.88 to 47.47. The surface hardness of the compomer was also significantly reduced after exposure to neutral foam. Therefore, the use of professionally applied topical fluorides, especially APF gel and foam, may be detrimental to the long-term durability of composite-based restoratives. PMID:12413222

Yap, Adrian U J; Mok, Betty Y Y

319

CONDENSED MATTER: STRUCTURE, MECHANICAL AND THERMAL PROPERTIES: Crystal Structure and High Hardness Mechanism of Orthorhomic Si2N2O  

NASA Astrophysics Data System (ADS)

A quasi-single-phase orthorombic Si2N2O compound is obtained by hot-pressing sintering using homogeneous precursors as raw materials under nitrogen atmosphere. The bulk hardness of orthorombic Si2N2O (o-Si2N2O) is investigated by a nanoindenter experiment; the results show that o-Si2N2O with maximal value about 19GPa has a high hardness covalent crystal besides ?-Si3N4. It is discovered that the high hardness is mainly attributed to the unique crystal structure. The bridging O atoms in the o-Si2N2O are responsible for decreasing hardness. It is found that the Si-O bonds in the open tetrahedral crystal structure are more easily broken and tilted than other bonds.

Xiong, Lan-Tian; Cao, Mao-Sheng; Hou, Zhi-Ling

2009-07-01

320

The nonuniform hard-rod fluid revisited  

NASA Astrophysics Data System (ADS)

The statistical mechanics of the one-dimensional nonuniform pure hard-core fluid is formulated in the spirit of the Reiss-Frisch-Lebowitz (RFL) scaled particle theory. By emphasizing the importance of the core dependence, a more intuitive and simpler derivation can be given. The Wiener-Hopf-type construction of the pair direct correlation function is formulated via the Dyson variational method of inverse scattering theory, which is compared with the particle-hole theory. The new approach allows us to lift the global free energy functional into a larger space where all the symmetries become apparent.

Zhang, M. Q.

1991-06-01

321

Hard X ray observations of galactic sources  

NASA Astrophysics Data System (ADS)

A number of galactic sources observed by the hard X-ray telescope Mifrasco during the course of two balloon flights from the Milo base in Trapani (Sicily) in July 1986 and 1987 are presented. Emission spectra was measured over the energy range 15 to 300 keV from the Crab nebula and the transient source A0535+26, and timing analyses were performed. Upper limits to the emission from the X-ray puslsar Her X-1 and the peculiar emission line object SS 433 were obtained.

Bazzano, A.; Carstairs, I. R.; Coe, M. J.; Court, A.; Davies, S. R.; Dean, A. J.; Dipper, N.; Lewis, R.; Maggioli, P.; Norton, A. J.

1989-11-01

322

Hardness assurance statistical methodology for semiconductor devices  

NASA Astrophysics Data System (ADS)

A statistical method is developed for determining electrical end-point limits for semiconductor devices subjected to radiation stress. The approach utilizes multiple lot radiation data and can be applied where lot-to-lot variations in radiation response are large compared to variations within a lot. Such limits may be used as design parameter limits or as failure limits for lot acceptance testing of future hardness-assured, semiconductor production lots. The method was applied for neutron and total gamma dose effects on low power bipolar transistors, digital TTL ICs, and a power transistor for which an adequate multiple-lot radiation database existed.

Arimura, I.; Namenson, A. I.

1983-12-01

323

Friction and wear characteristics of hard coatings  

Microsoft Academic Search

The friction and wear behavior of four hard coatings (Metco, Diamalloy, Stellite, and Zn?SiC) was determined using a pin-on-disk machine. The coatings were thermal sprayed on cast iron disks. The coating compositions were Ni?17Cr?2.5Fe?2.5Si?2.5B?0.15C (Metco), Fe?30Mo?2C (Diamalloy), Co?30Cr?12W?2.4C (Stellite), and Zn?50SiC (Zn?SiC). Sliding was performed between cylindrical pins machined from non-asbestos organic (NAO) brake lining and the coated and uncoated

Malcolm K Stanford; Vinod K Jain

2001-01-01

324

Hard pion bremsstrahlung in the Coulomb region  

SciTech Connect

Hard high-energy pion-nucleus bremsstrahlung, {pi}{sup -}+A{yields}{pi}{sup -}+{gamma}+A, is studied in the Coulomb region, i.e., the small-angle region where the nuclear scattering is dominated by the Coulomb interaction. Special attention is focussed on the possibility of measuring the pion polarizability in such reactions. We study the sensitivity to the structure of the underlying pion-Compton amplitude through a model with {sigma},{rho}, and a{sub 1} exchanges. It is found that the effective energy in the virtual pion-Compton scattering is often so large that the threshold approximation does not apply.

Faeldt, Goeran; Tengblad, Ulla [Department of Nuclear and Particle Physics, Uppsala University, Box 535, S-751 21 Uppsala (Sweden)

2007-12-15

325

Hard Exclusive Vector Meson Leptoproduction At HERMES  

SciTech Connect

The HERMES experiment at DESY, Hamburg collected a set of data on hard exclusive vector meson ({rho}{sup 0}{phi},{omega}) leptoproduction using the 27.6 GeV longitudinally polarized lepton beam of HERA accelerator and longitudinally or transversely polarized or unpolarized gas targets. Measurements of exclusive vector meson production provide access to the structure of the nucleon since the process can be described in terms of Generalized Parton Distributions (GPDs). An overview of the HERMES results on exclusive vector mesons production is presented.

Golembiovskaya, M. [DESY, Notkestrasse 85, 22607, Hamburg (Germany)

2011-07-15

326

Magnetic susceptibility and hardness of Au-xPt-yNb alloys for biomedical applications.  

PubMed

Metal devices in the human body induce serious metal artifacts in magnetic resonance imaging (MRI). Metals artifacts are mainly caused by a volume magnetic susceptibility (?v) mismatch between a metal device and human tissue. In this research, Au-xPt-yNb alloys were developed for fabricating MRI artifact-free biomedical metal devices. The magnetic properties, hardness and phase constitutions of these alloys were investigated. The Au-xPt-8Nb alloys showed satisfactory ?v values. Heat treatments did not clearly change the ?v values for Au-xPt-8Nb alloys. The Vickers hardness (HV) of these two alloys was much higher than that of high-Pt alloys; moreover, aging at 700°C increased the HV values of these two alloys. A dual phase structure consisting of face-centered cubic ?1 and ?2 phases was observed and aging at 700°C promoted phase separation. The Au-5Pt-8Nb and Au-10Pt-8Nb alloys showed satisfactory ?v values and high hardness and are thus suggested as candidates for MRI artifact-free alloys for biomedical applications. PMID:23747327

Uyama, Emi; Inui, Shihoko; Hamada, Kenichi; Honda, Eiichi; Asaoka, Kenzo

2013-06-04

327

Effects of explosions in hard rocks  

SciTech Connect

This work relates to explosions in hard rocks (ex: basalt, granite, limestone{hor_ellipsis}). Hard rock masses typically have a blocky structure created by the existence of geologic discontinuities such as bedding contacts, faults, and joints. At very high pressure-hundreds of kilobars and above-these discontinuities do not act separately, and the rock appears to be an equivalent continuous medium. At stress of a few tens of kilobars and below, the geologic discontinuities control the kinematics of the rock masses. Hence, the simulation of rock dynamics, anywhere but in the very-near source region, should account for those kinematics. In the very high pressure range continuum-based analysis is appropriate. In the discrete motion range one could consider: an equivalent continuum approach with anisotropy and plasticity. However, this is unlikely to provide the right kinematics; embedding discontinuities in continuum models, such as using joint elements and slip surfaces in finite elements. Typically, these are limited in terms of the separation of elements which may reconnect arbitrarily to new elements; complete discrete methods; ex: discrete elements, discontinuous displacement analysis (DDA). Discrete elements have progressed further than DDA We have chosen to develop and apply discrete elements models to explosion phenomenology in rocks.

Heuze, F.E.; Walton, O.R.; Maddix, D.M.; Shaffer, R.J.; Butkovich, T.R.

1993-05-01

328

Generalized Flory theory for hard alkane fluids  

NASA Astrophysics Data System (ADS)

Generalized Flory-dimer (GF-D) theory is extended to hard n-alkane fluids modelled as fused hard spheres constrained according to the rotational isomeric state approximation. Theoretical predictions for the second to the fifth virial coefficients for each conformer from n-butane to n-octane are compared with numerical results. Predictions for the second viral coefficient are in excellent agreement with recent simulation results; however, GF-D theory systematically overpredicts the third virial coefficient and underpredicts the fourth and the fifth virial coefficients. GF-D predictions for the compressibility factor for n-alkanes from n-butane to n-octane are compared with molecular dynamic simulation results for a closely related model. Despite the over- and underprediction of the individual virial coefficients, excellent agreement is observed between theory and simulation for the compressibility factors of n-butane and n-pentane using no adjustable parameters. However, in the cases of n-hexane, n-heptane and n-octane, GF-D theory slightly underpredicts the pressure at high volume fractions. Theoretical considerations suggest that probably the predictions of GF-D theory will deteriorate with increasing chain length.

Mehta, Sameer D.; Honnell, Kevin G.

329

Values Clarification: An Appraisal  

ERIC Educational Resources Information Center

|Presents a critique of the values clarification model as developed by Louis E. Raths and associates in such works as "Values and Teaching: Working with Values in the Classroom" and "Values Clarification: A Handbook of Suggestions". They are critically evaluated with reference to theoretical considerations and to other models of moral and values…

Harrison, John L.

1976-01-01

330

A multi-step system for screening and localization of hard exudates in retinal images  

NASA Astrophysics Data System (ADS)

The number of people being affected by Diabetes mellitus worldwide is increasing at an alarming rate. Monitoring of the diabetic condition and its effects on the human body are therefore of great importance. Of particular interest is diabetic retinopathy (DR) which is a result of prolonged, unchecked diabetes and affects the visual system. DR is a leading cause of blindness throughout the world. At any point of time 25 - 44% of people with diabetes are afflicted by DR. Automation of the screening and monitoring process for DR is therefore essential for efficient utilization of healthcare resources and optimizing treatment of the affected individuals. Such automation would use retinal images and detect the presence of specific artifacts such as hard exudates, hemorrhages and soft exudates (that may appear in the image) to gauge the severity of DR. In this paper, we focus on the detection of hard exudates. We propose a two step system that consists of a screening step that classifies retinal images as normal or abnormal based on the presence of hard exudates and a detection stage that localizes these artifacts in an abnormal retinal image. The proposed screening step automatically detects the presence of hard exudates with a high sensitivity and positive predictive value (PPV ). The detection/localization step uses a k-means based clustering approach to localize hard exudates in the retinal image. Suitable feature vectors are chosen based on their ability to isolate hard exudates while minimizing false detections. The algorithm was tested on a benchmark dataset (DIARETDB1) and was seen to provide a superior performance compared to existing methods. The two-step process described in this paper can be embedded in a tele-ophthalmology system to aid with speedy detection and diagnosis of the severity of DR.

Bopardikar, Ajit S.; Bhola, Vishal; Raghavendra, B. S.; Narayanan, Rangavittal

2012-02-01

331

Phase transition induced by a shock wave in hard-sphere and hard-disk systems.  

PubMed

Dynamic phase transition induced by a shock wave in hard-sphere and hard-disk systems is studied on the basis of the system of Euler equations with caloric and thermal equations of state. First, Rankine-Hugoniot conditions are analyzed. The quantitative classification of Hugoniot types in terms of the thermodynamic quantities of the unperturbed state (the state before a shock wave) and the shock strength is made. Especially Hugoniot in typical two possible cases (P-1 and P-2) of the phase transition is analyzed in detail. In the case P-1 the phase transition occurs between a metastable liquid state and a stable solid state, and in the case P-2 the phase transition occurs through coexistence states, when the shock strength changes. Second, the admissibility of the two cases is discussed from a viewpoint of the recent mathematical theory of shock waves, and a rule with the use of the maximum entropy production rate is proposed as the rule for selecting the most probable one among the possible cases, that is, the most suitable constitutive equation that predicts the most probable shock wave. According to the rule, the constitutive equation in the case P-2 is the most promising one in the dynamic phase transition. It is emphasized that hard-sphere and hard-disk systems are suitable reference systems for studying shock wave phenomena including the shock-induced phase transition in more realistic condensed matters. PMID:18698913

Zhao, Nanrong; Sugiyama, Masaru; Ruggeri, Tommaso

2008-08-01

332

Nanoindentation hardness of soft films on hard substrates: Effects of the substrate  

SciTech Connect

The ability to accurately measure the mechanical properties of thin metallic films is important in the semiconductor industry as it relates to device reliability issues. One popular technique for measuring thin film mechanical properties is nanoindentation. This technique has the advantage of being able to measure properties such as hardness and elastic modulus without removing a film from its substrate. However, according to a widely-held rule of thumb, intrinsic film properties can be measured in a manner which is not influenced by the substrate only if the indentation depth is kept to less than 10% of the film thickness, which is often not practical. In this work, a method for making substrate independent hardness measurements of soft metallic films on hard substrates is proposed. The primary issue to be addressed is the substrate-induced enhancement of indentation pile-up and the ways in which this pile-up influences the contact area determined from analyses of nanoindentation load- displacement data. Based on experimental observations of soft aluminum films on silicon, glass, and sapphire substrates, a simple empirical relationship is derived which relates the amount of pile-up to the contact depth. From this relationship, a simple method is developed which allows the intrinsic hardness of the film to be measured by nanoindentation methods even when the indenter penetrates through the film into the substrate.

Tsui, T.Y. [Advanced Micro Devices, Sunnyvale, CA (United States); Ross, C.A. [Massachusetts Institute of Technology, Cambridge, MA (United States). Dept. of Materials Science and Engineering; Pharr, G.M. [Rice Univ., Houston, TX (United States). Dept. of Materials Science

1997-06-01

333

Capillary nematization of hard colloidal platelets confined between two parallel hard walls  

Microsoft Academic Search

We use density functional theory to study the capillary phase behaviour of a discotic system of colloidal platelets that are confined in a planar slit pore. The model plates have circular shape, continuous orientations and vanishing thickness; they interact via hard-core repulsion with each other and with the walls which induces homeotropic wall anchoring of the nematic director. We find

Hendrik Reich; Matthias Schmidt

2007-01-01

334

Hard-Boiled for Hard Times in Leonardo Padura Fuentes's Detective Fiction  

ERIC Educational Resources Information Center

Focusing on Leonardo Padura Fuentes's hard-boiled fiction, this essay traces the origin and evolution of the genre in Cuba. Padura Fuentes has challenged the officially sanctioned socialist "literatura policial" that became popular in the 1970s and 1980s. creating a new model of criticism that is not afraid to confront the island's socio-economic…

Song, H. Rosi

2009-01-01

335

Hard-Boiled for Hard Times in Leonardo Padura Fuentes's Detective Fiction  

ERIC Educational Resources Information Center

|Focusing on Leonardo Padura Fuentes's hard-boiled fiction, this essay traces the origin and evolution of the genre in Cuba. Padura Fuentes has challenged the officially sanctioned socialist "literatura policial" that became popular in the 1970s and 1980s. creating a new model of criticism that is not afraid to confront the island's socio-economic…

Song, H. Rosi

2009-01-01

336

Phase transition induced by a shock wave in hard-sphere and hard-disk systems  

NASA Astrophysics Data System (ADS)

Dynamic phase transition induced by a shock wave in hard-sphere and hard-disk systems is studied on the basis of the system of Euler equations with caloric and thermal equations of state. First, Rankine-Hugoniot conditions are analyzed. The quantitative classification of Hugoniot types in terms of the thermodynamic quantities of the unperturbed state (the state before a shock wave) and the shock strength is made. Especially Hugoniot in typical two possible cases (P-1 and P-2) of the phase transition is analyzed in detail. In the case P-1 the phase transition occurs between a metastable liquid state and a stable solid state, and in the case P-2 the phase transition occurs through coexistence states, when the shock strength changes. Second, the admissibility of the two cases is discussed from a viewpoint of the recent mathematical theory of shock waves, and a rule with the use of the maximum entropy production rate is proposed as the rule for selecting the most probable one among the possible cases, that is, the most suitable constitutive equation that predicts the most probable shock wave. According to the rule, the constitutive equation in the case P-2 is the most promising one in the dynamic phase transition. It is emphasized that hard-sphere and hard-disk systems are suitable reference systems for studying shock wave phenomena including the shock-induced phase transition in more realistic condensed matters.

Zhao, Nanrong; Sugiyama, Masaru; Ruggeri, Tommaso

2008-08-01

337

Chemical-potential route: a hidden Percus-Yevick equation of state for hard spheres.  

PubMed

The chemical potential of a hard-sphere fluid can be expressed in terms of the contact value of the radial distribution function of a solute particle with a diameter varying from zero to that of the solvent particles. Exploiting the explicit knowledge of such a contact value within the Percus-Yevick theory, and using standard thermodynamic relations, a hitherto unknown Percus-Yevick equation of state, p/?k(B)T = -(9/?) ln(1-?)-(16-31?)/2(1-?)(2), is unveiled. This equation of state turns out to be better than the one obtained from the conventional virial route. Interpolations between the chemical-potential and compressibility routes are shown to be more accurate than the widely used Carnahan-Starling equation of state. The extension to polydisperse hard-sphere systems is also presented. PMID:23005929

Santos, Andrés

2012-09-17

338

Chemical-Potential Route: A Hidden Percus-Yevick Equation of State for Hard Spheres  

NASA Astrophysics Data System (ADS)

The chemical potential of a hard-sphere fluid can be expressed in terms of the contact value of the radial distribution function of a solute particle with a diameter varying from zero to that of the solvent particles. Exploiting the explicit knowledge of such a contact value within the Percus-Yevick theory, and using standard thermodynamic relations, a hitherto unknown Percus-Yevick equation of state, p/?kBT=-(9/?)ln?(1-?)-(16-31?)/2(1-?)2, is unveiled. This equation of state turns out to be better than the one obtained from the conventional virial route. Interpolations between the chemical-potential and compressibility routes are shown to be more accurate than the widely used Carnahan-Starling equation of state. The extension to polydisperse hard-sphere systems is also presented.

Santos, Andrés

2012-09-01

339

The value of GOLD  

Microsoft Academic Search

You worked hard the past few years and finally graduated. You landed a job and picked out where you are going to live. Everything has been planned out and what you've missed you'll figure out after you have moved. If you're like me when I graduated, then you'll likely be surprised at how your life is about to change. Graduation

Uri Moszkowicz

2009-01-01

340

Debating Propositions of Value.  

ERIC Educational Resources Information Center

|Advances a rationale for debating propositions of value in interscholastic contests. Considers implications for burden of proof, presumption, and the location of issues in value propositions, and proposes a preliminary system for the analysis of value propositions. (JMF)|

Matlon, Ronald J.

1978-01-01

341

Fluid-solid transition in hard hypersphere systems  

NASA Astrophysics Data System (ADS)

In this work we present a numerical study, based on molecular dynamics simulations, to estimate the freezing point of hard spheres and hypersphere systems in dimension D = 4, 5, 6, and 7. We have studied the changes of the radial distribution function (RDF) as a function of density in the coexistence region. We started our simulations from crystalline states with densities above the melting point, and moved down to densities in the liquid state below the freezing point. For all the examined dimensions (including D = 3), it was observed that the height of the first minimum of the RDF changes in an almost continuous way around the freezing density and resembles a second order phase transition. With these results we propose a numerical method to estimate the freezing point as a function of the dimension D using numerical fits and semiempirical approaches. We find that the estimated values of the freezing point are very close to the previously reported values from simulations and theoretical approaches up to D = 6, reinforcing the validity of the proposed method. This was also applied to numerical simulations for D = 7 giving new estimations of the freezing point for this dimensionality.

Estrada, C. D.; Robles, M.

2011-01-01

342

Voronoi neighbor statistics of homogeneously sheared inelastic hard disks and hard spheres  

NASA Astrophysics Data System (ADS)

In this work we extend our earlier Voronoi neighbor analysis [J. Chem. Phys. 123, 074502 (2005)] to homogeneously sheared inelastic hard-particle structures, the simplest model for rapid granular matter. The pair distribution function is partitioned into the nth neighbor coordination number (Cn) , and the nth neighbor position distribution [fn(r)] . The distribution of the number of Voronoi faces (Pn) is also considered since C1 is its mean. We report the Cn and Pn for the homogeneously sheared inelastic hard-disk and hard-sphere structures. These statistics are sensitive to shear ordering transition, the nonequilibrium analogue of the freezing transition. In the near-elastic limit, the sheared fluid statistics approach that of the thermodynamic fluid. On shear ordering, due to the onset of order, the Cn for sheared structures approach that of the thermodynamic solid phase. The suppression of nucleation by the homogeneous shear is evident in these statistics. As inelasticity increases, the shear ordering packing fraction increases. Due to the topological instability of the isotropically perturbed face-centered cubic lattice, polyhedra with faces 12 to 18, with a mean at 14, coexist even in the regular close packed limit for the thermodynamic hard-sphere solid. In shear ordered inelastic hard-sphere structures there is a high incidence of 14-faceted polyhedra and a consequent depletion of polyhedra with faces 12, 13, 15-18, due to the formation of body-centered-tetragonal (bct) structures. These bct structures leave a body-centered-cubic-like signature in the Cn and Pn data. On shear ordering, close-packed layers slide past each other. However, with a velocity-dependent coefficient of restitution, at a critical shear rate these layers get disordered or amorphized. We find that the critical shear rate for amorphization is inversely proportional to the particle diameter, as compared to the inverse square scaling observed in dense colloidal suspensions.

Senthil Kumar, V.; Kumaran, V.

2006-05-01

343

Confinement of hot, hard x-ray producing electrons in solar flares  

Microsoft Academic Search

Possible thermal models for solar, hard X-ray emission, consisting of small volumes in which the electrons are rapidly heated to 4 x 10⁸ K, are examined to determine under what conditions such models can be more efficient than nonthermal models. The primary energy-loss mechanism in these models is source expansion due to heat conduction which deviates from its classical value

D. F. Smith; C. G. Lilliequist

1979-01-01

344

Friction and the development of hard alloy surface microstructures during wear  

NASA Astrophysics Data System (ADS)

Investigations of wear in sliding friction of WC-Hadfield steel hard alloy against cast tool steel have been carried out in a broad range of velocities and pressure values. Structural and phase composition variations have been revealed. Friction-affected zone was found to be 450 µm in depth. Structural ? ? ?, ? ? transformation regions are located within 100 ?m of the surface. These transformations contributed to the total solid solution deformation hardening.

Gnyusov, S. F.; Tarassov, S. Yu.

1997-12-01

345

Competitive analysis of online real-time scheduling algorithms under hard energy constraint  

Microsoft Academic Search

In this paper, we undertake the competitive analysis of the online real-time scheduling problems under a given hard energy\\u000a constraint. Specifically, we derive worst-case performance bounds that apply to any online algorithm, when compared to an\\u000a optimal algorithm that has the knowledge of the input sequence in advance. First, by focusing on uniform value-density settings,\\u000a we prove that no online

Vinay Devadas; Fei Li; Hakan Aydin

2010-01-01

346

HIGHER ORDER HARD EDGE END FIELD EFFECTS.  

SciTech Connect

In most cases, nonlinearities from magnets must be properly included in tracking and analysis to properly compute quantities of interest, in particular chromatic properties and dynamic aperture. One source of nonlinearities in magnets that is often important and cannot be avoided is the nonlinearity arising at the end of a magnet due to the longitudinal variation of the field at the end of the magnet. Part of this effect is independent of the longitudinal of the end. It is lowest order in the body field of the magnet, and is the result of taking a limit as the length over which the field at the end varies approaches zero. This is referred to as a ''hard edge'' end field. This effect has been computed previously to lowest order in the transverse variables. This paper describes a method to compute this effect to arbitrary order in the transverse variables, under certain constraints.

BERG,J.S.

2004-09-14

347

Directional Entropic Forces in Hard Colloids  

NASA Astrophysics Data System (ADS)

Based on known results from the literature of hard particles we introduce the concept of entropically patchy particles -- particles that bind with angular specificity entirely due to their geometry via directional entropic forces or ``bonds''. Unlike ordinary patchy particles, in which ``valence'' vis-a-vis angular specificity is dictated by microscopic energetic considerations (sticky patches), entropic forces causing the binding of particles at entropic patch sites are emergent. Using basic examples we show both theoretically and computationally that we can alter the geometry of a particle to create an entropic patch and tune the resulting effective pair potential in such a way that it can lead to angularly specific binding, even in the absence of depletants.

van Anders, Greg; Ahmed, Khalid; Smith, Ross; Engel, Michael; Glotzer, Sharon

2013-03-01

348

Crystallization in glassy suspensions of hard ellipsoids.  

PubMed

We have carried out computer simulations of overcompressed suspensions of hard monodisperse ellipsoids and observed their crystallization dynamics. The system was compressed very rapidly in order to reach the regime of slow, glass-like dynamics. We find that, although particle dynamics become sub-diffusive and the intermediate scattering function clearly develops a shoulder, crystallization proceeds via the usual scenario: nucleation and growth for small supersaturations, spinodal decomposition for large supersaturations. In particular, we compared the mobility of the particles in the regions where crystallization set in with the mobility in the rest of the system. We did not find any signature in the dynamics of the melt that pointed towards the imminent crystallization events. PMID:24089787

Dorosz, Sven; Schilling, Tanja

2013-09-28

349

Using Cell Phone Keyboards Is (NP) Hard  

NASA Astrophysics Data System (ADS)

Sending text messages on cell phones which only contain the keys 0 through 9 and # and * can be a painful experience. We consider the problem of designing an optimal mapping of numbers to sets of letters to act as an alternative to the standard {2?{abc}, 3?{def}...}. Our overall goal is to minimize the expected number of buttons that must be pressed to enter a message in English. Some variations of the problem are efficiently solvable, either by being small instances or by being in P, but the most realistic version of the problem is NP hard. To prove NP-completeness, we describe a new graph coloring problem UniquePathColoring. We also provide numerical results for the English language on a standard corpus which describe several mappings that improve upon the standard one. With luck, one of these new mappings will achieve success similar to that of the Dvorak layout for computer keyboards.

Boothe, Peter

350

Crystallization in glassy suspensions of hard ellipsoids  

NASA Astrophysics Data System (ADS)

We have carried out computer simulations of overcompressed suspensions of hard monodisperse ellipsoids and observed their crystallization dynamics. The system was compressed very rapidly in order to reach the regime of slow, glass-like dynamics. We find that, although particle dynamics become sub-diffusive and the intermediate scattering function clearly develops a shoulder, crystallization proceeds via the usual scenario: nucleation and growth for small supersaturations, spinodal decomposition for large supersaturations. In particular, we compared the mobility of the particles in the regions where crystallization set in with the mobility in the rest of the system. We did not find any signature in the dynamics of the melt that pointed towards the imminent crystallization events.

Dorosz, Sven; Schilling, Tanja

2013-09-01

351

Nanomechanics of hard films on compliant substrates.  

SciTech Connect

Development of flexible thin film systems for biomedical, homeland security and environmental sensing applications has increased dramatically in recent years [1,2,3,4]. These systems typically combine traditional semiconductor technology with new flexible substrates, allowing for both the high electron mobility of semiconductors and the flexibility of polymers. The devices have the ability to be easily integrated into components and show promise for advanced design concepts, ranging from innovative microelectronics to MEMS and NEMS devices. These devices often contain layers of thin polymer, ceramic and metallic films where differing properties can lead to large residual stresses [5]. As long as the films remain substrate-bonded, they may deform far beyond their freestanding counterpart. Once debonded, substrate constraint disappears leading to film failure where compressive stresses can lead to wrinkling, delamination, and buckling [6,7,8] while tensile stresses can lead to film fracture and decohesion [9,10,11]. In all cases, performance depends on film adhesion. Experimentally it is difficult to measure adhesion. It is often studied using tape [12], pull off [13,14,15], and peel tests [16,17]. More recent techniques for measuring adhesion include scratch testing [18,19,20,21], four point bending [22,23,24], indentation [25,26,27], spontaneous blisters [28,29] and stressed overlayers [7,26,30,31,32,33]. Nevertheless, sample design and test techniques must be tailored for each system. There is a large body of elastic thin film fracture and elastic contact mechanics solutions for elastic films on rigid substrates in the published literature [5,7,34,35,36]. More recent work has extended these solutions to films on compliant substrates and show that increasing compliance markedly changes fracture energies compared with rigid elastic solution results [37,38]. However, the introduction of inelastic substrate response significantly complicates the problem [10,39,40]. As a result, our understanding of the critical relationship between adhesion, properties, and fracture for hard films on compliant substrates is limited. To address this issue, we integrated nanomechanical testing and mechanics-based modeling in a program to define the critical relationship between deformation and fracture of nanoscale films on compliant substrates. The approach involved designing model film systems and employing nano-scale experimental characterization techniques to isolate effects of compliance, viscoelasticity, and plasticity on deformation and fracture of thin hard films on substrates that spanned more than two orders of compliance magnitude exhibit different interface structures, have different adhesion strengths, and function differently under stress. The results of this work are described in six chapters. Chapter 1 provides the motivation for this work. Chapter 2 presents experimental results covering film system design, sample preparation, indentation response, and fracture including discussion on the effects of substrate compliance on fracture energies and buckle formation from existing models. Chapter 3 describes the use of analytical and finite element simulations to define the role of substrate compliance and film geometry on the indentation response of thin hard films on compliant substrates. Chapter 4 describes the development and application of cohesive zone model based finite element simulations to determine how substrate compliance affects debond growth. Chapter 5 describes the use of molecular dynamics simulations to define the effects of substrate compliance on interfacial fracture of thin hard tungsten films on silicon substrates. Chapter 6 describes the Workshops sponsored through this program to advance understanding of material and system behavior.

Reedy, Earl David, Jr. (Sandia National Laboratories, Albuquerque, NM); Emerson, John Allen (Sandia National Laboratories, Albuquerque, NM); Bahr, David F. (Washington State University, Pullman, WA); Moody, Neville Reid; Zhou, Xiao Wang; Hales, Lucas (University of Minnesota, Minneapolis, MN); Adams, David Price (Sandia National Laboratories, Albuquerque, NM); Yeager,John (Washington State University, Pullman, WA); Nyugen, Thao D. (Johns Hopkins University, Baltimore, MD); Corona, Edmundo (Sandia National Laboratories, Albuquerque, NM); Kennedy, Marian S. (Clemson University, Clemson, SC); Cordill, Megan J. (Erich Schmid Institute, Leoben, Austria)

2009-09-01

352

Hard scattering phenomena from RHIC to LHC  

SciTech Connect

In the Relativistic Heavy Ion Collider era the high-p{sub T} particle emerging from hard scattering became an important tool of exploration of excited nuclear medium formed in ultra-relativistic heavy ion collisions. Discovery of anomalous suppression of high-p{sub T} particle yield [1] together with an observation of disappearance of back-to-back hadron correlation in central Au+Au collisions in 2002 [2] were the key results interpreted as a manifestation of the deconfined QCD medium in heavy ion collisions. Analysis of the high-p{sub T} particle and jet production is already a standard experimental technique providing a test bench for pQCD description of the point-like constituent scattering in p+p collisions and sensitive probes of the excited nuclear medium in A+A collisions.

Rak, Jan [Jyvaeskylae University, FI-40014 Jyvaeskylae (Finland)

2011-05-23

353

Crystal nucleation of colloidal hard dumbbells  

NASA Astrophysics Data System (ADS)

Using computer simulations, we investigate the homogeneous crystal nucleation in suspensions of colloidal hard dumbbells. The free energy barriers are determined by Monte Carlo simulations using the umbrella sampling technique. We calculate the nucleation rates for the plastic crystal and the aperiodic crystal phase using the kinetic prefactor as determined from event driven molecular dynamics simulations. We find good agreement with the nucleation rates determined from spontaneous nucleation events observed in event driven molecular dynamics simulations within error bars of one order of magnitude. We study the effect of aspect ratio of the dumbbells on the nucleation of plastic and aperiodic crystal phases, and we also determine the structure of the critical nuclei. Moreover, we find that the nucleation of the aligned close-packed crystal structure is strongly suppressed by a high free energy barrier at low supersaturations and slow dynamics at high supersaturations.

Ni, Ran; Dijkstra, Marjolein

2011-01-01

354

Hard target penetration acceleration signals Time-frequency Analysis  

Microsoft Academic Search

The hard target penetration process is very complex and the various missile vibration signals are very rich. So Hard target penetration acceleration signals are non-stationary signals. We use the Hilbert-Huang transform (HHT) for Time­ frequency Analysis non-stationary signals in noisy environments. Empirical Mode Decomposition (EMD) is hard core of HHT so these maybes bring Mode Mixing. We put forward a

Huiyan Hao; Hui Zhao

2011-01-01

355

Rate-hardness: a new performance metric for haptic interfaces  

Microsoft Academic Search

Rate-hardness is introduced as a quality metric for hard virtual surfaces, and linked to human perception of hardness via a psychophysical study. A 3 degree-of-freedom haptic interface is used to present pairs of virtual walls to users for side-by-side comparison, 19 subjects are tested in a series of three blocks of trials, where different virtual walls are presented in randomly

Dale A. Lawrence; Lucy Y. Pao; Anne M. Dougherty; Mark A. Salada; Yiannis Pavlou

2000-01-01

356

Freeze-out of salts in hard-water lakes  

Microsoft Academic Search

A 1Syear series of daily measurements of pH and total alkalinity recorded at the water intake of a municipal water-treatment plant on Clear Lake, Iowa, demonstrated that rapid chemical changes occur annually as the ice cover melts. Additional measurements of total and calcium hardness on this and three other eutrophic, hard-water lakes showed that total and calcium hardness concentrations declined

DANIEL E. CANFIELD; ROGER W. BACHMANN; MARK V. HOYER

1983-01-01

357

Radiation Hard AlGaN Detectors and Imager  

SciTech Connect

Radiation hardness of AlGaN photodiodes was tested using a 65 MeV proton beam with a total proton fluence of 3x10{sup 12} protons/cm{sup 2}. AlGaN Deep UV Photodiode have extremely high radiation hardness. These new devices have mission critical applications in high energy density physics (HEDP) and space explorations. These new devices satisfy radiation hardness requirements by NIF. NSTec is developing next generation AlGaN optoelectronics and imagers.

None

2012-05-01

358

Clique-width minimization is NP-hard  

Microsoft Academic Search

Clique-width is a graph parameter that measures in a certain sense the complexity of a graph. Hard graph problems (e.g., problems expressible in Monadic Second Order Logic with second-order quantification on vertex sets, that includes NP-hard problems) can be solved efficiently for graphs of small clique-width. It is widely believed that determining the clique-width of a graph is NP-hard; in

Michael R. Fellows; Frances A. Rosamond; Udi Rotics; Stefan Szeider

2006-01-01

359

Shielding a streak camera from hard x rays  

SciTech Connect

The targets used in the hot halfraum campaign at OMEGA create many hot electrons, which result in a large flux of hard x rays. The hard x rays produce a high background in the streak camera. The background was significantly reduced by wrapping the streak camera with a high-Z material; in this case, 1/8 in. of Pb. The large hard x-ray flux also adds noise to images from framing cameras which use charge-coupled devices.

Schneider, M.B.; Sorce, C.; Loughman, K.; Emig, J.; Bruns, C.; Back, C.; Bell, P.M.; Compton, S.; Hargrove, D.; Holder, J.P.; Landen, O.L.; Perry, T.S.; Shepherd, R.; Young, B.K. [Lawrence Livermore National Laboratory, P.O. Box 808, L-472 Livermore, California 94550 (United States)

2004-10-01

360

Coendangered hard-ticks: threatened or threatening?  

PubMed Central

The overwhelming majority of animal conservation projects are focused on vertebrates, despite most of the species on Earth being invertebrates. Estimates state that about half of all named species of invertebrates are parasitic in at least one stage of their development. The dilemma of viewing parasites as biodiversity or pest has been discussed by several authors. However, ticks were omitted. The latest taxonomic synopses of non-fossil Ixodidae consider valid 700 species. Though, how many of them are still extant is almost impossible to tell, as many of them are known only from type specimens in museums and were never collected since their original description. Moreover, many hosts are endangered and as part of conservation efforts of threatened vertebrates, a common practice is the removal of, and treatment for external parasites, with devastating impact on tick populations. There are several known cases when the host became extinct with subsequent coextinction of their ectoparasites. For our synoptic approach we have used the IUCN status of the host in order to evaluate the status of specifically associated hard-ticks. As a result, we propose a number of 63 coendangered and one extinct hard-tick species. On the other side of the coin, the most important issue regarding tick-host associations is vectorial transmission of microbial pathogens (i.e. viruses, bacteria, protozoans). Tick-borne diseases of threatened vertebrates are sometimes fatal to their hosts. Mortality associated with pathogens acquired from ticks has been documented in several cases, mostly after translocations. Are ticks a real threat to their coendangered host and should they be eliminated? Up to date, there are no reliable proofs that ticks listed by us as coendangered are competent vectors for pathogens of endangered animals.

2011-01-01

361

Values: A Symposium Report.  

ERIC Educational Resources Information Center

This publication brings together a set of four papers prepared for a symposium on values at the 1972 annual meeting of the American Educational Research Association. The first paper, by Fred N. Kerlinger, establishes a rationale for values research. The discussion focuses on the definition of values, relationship between values and attitudes,…

Ryan, T. A., Ed.

362

Teaching Absolute Value Meaningfully  

ERIC Educational Resources Information Center

|What is the meaning of absolute value? And why do teachers teach students how to solve absolute value equations? Absolute value is a concept introduced in first-year algebra and then reinforced in later courses. Various authors have suggested instructional methods for teaching absolute value to high school students (Wei 2005; Stallings-Roberts…

Wade, Angela

2012-01-01

363

Religion and Value Systems  

Microsoft Academic Search

Uncovering the complex relationships between religiosity and values may provide a better understanding of what it means to be religious or nonreligious. This article reviews research on values and religiosity across cultural and religious groups. Although religious groups differ in the importance they attribute to different values, the pattern of correlations between religiosity and values is strikingly consistent across monotheistic

Sonia Roccas

2005-01-01

364

On Literature and Values.  

ERIC Educational Resources Information Center

|In reviewing the ancient, well-worn debate on the relationship between literature and values, it may be seen that the current pedagogical theory of developing response to literature is parallel to the argument for helping students articulate their own values. Two approaches to clarifying values are the values clarification approach (Louis Raths,…

Beach, Richard

365

Hardness of covalent compounds: Roles of metallic component and d valence electrons  

NASA Astrophysics Data System (ADS)

Based on the detailed analysis of chemical bonds, we present a Vickers hardness expression for the covalency-dominant crystals such as transition-metal carbides and nitrides. Hardness is dependent not only on bond length, bond density, and ionicity of bond [F. M. Gao et al., Phys. Rev. Lett. 91, 015502 (2003)] but also on the metallicity of bond and orbital form in the crystal structure of a compound, and all of these parameters can be determined by first-principles calculations. The calculated hardness using our expression has a good agreement with the experimental values for known monocarbides, mononitrides of transition metals, and cubic Zr3N4 with Th3P4 structure. In addition, we have predicted the Vickers hardness of the recently predicted tetragonal BC3 and tetragonal B2CN, and the recently synthesized pyrite PtN2 and marcasite OsN2. Our method offers one useful technique to search for superhard materials in transition-metal carbides and nitrides.

Guo, Xiaoju; Li, Lei; Liu, Zhongyuan; Yu, Dongli; He, Julong; Liu, Riping; Xu, Bo; Tian, Yongjun; Wang, Hui-Tian

2008-07-01

366

Numerical investigation of airflow inside a 1-in hard disk drive  

NASA Astrophysics Data System (ADS)

The increasing application of the hard disk drive in consumer electronic devices has pushed the usage of the small form factor hard drives. At the same time, the data storage industry continues to enhance the capacity and performance of computer hard disk drive. The concerns of track mis-registration caused by various runout still remain with the form factor change. The objective of the current study is to numerically investigate the airflow characteristic inside a 1 in hard disk drive. The simulation model is constructed based on the currently available 1-in micro-drive in the market, with 3600 rpm disk rotation speed, thus the flow Reynolds number based on the disk tip radius is around 4.8×103. Two models with different actuator arm positions (outside and middle-disk) were studied. The simulation results show that the standard k-epsilon model used allows us to extract similar information and understanding as that from more developed numerical model. Good agreement in normalized velocity magnitude and flow pattern is observed between the numerical and experimental results. At different actuator arm positions, streamlines and velocity vectors plots show the effect of the actuator arm position to the flow pattern, especially around the arm. This arm position also affects the radial and tangential shear stress values over the disk, which may help to estimate the wind loss and power consumption.

Suriadi, M. A.; Tan, C. S.; Zhang, Q. D.; Yip, T. H.; Sundaravadivelu, K.

2006-08-01

367

1500 Gate standard cell compatible radiation hard gate array  

SciTech Connect

The G1500 gate array combines Sandia Labs' 4/3..mu.. CMOS silicon gate radiation hard process with a novel gate isolated standard cell compatible design for quick turnaround time, low cost, and radiation hardness. This device is hard to 5 x 10/sup 5/ rads, utilizes a configuration that provides high packing density, and is supported on both the Daisy and Mentor workstations. This paper describes Sandia Labs' radiation hard 4/3..mu.. process, the G1500's unique design, and the complete design capabilities offered by the workstations.

Mills, B.D.; Shafer, B.D.; Melancon, E.P.

1984-11-01

368

Mechanical Properties of Chocolate: How Hard is your Chocolate?  

NSDL National Science Digital Library

Hardness is probably a concept you are well familiar with. You already know that certain materials are harder than others; in fact, you prove it everyday when you chew your food and your teeth don’t break (because your teeth are harder than the foods you chew). Hardness can be defined as a material's ability to resist a change in shape. Modern hardness testers take a well-defined shape and press it into a material with a certain force, observing the indent it leaves in the material when it is removed. In this lesson, you will be performing hardness testing on different bars of chocolate.

2007-12-20

369

How to estimate hardness of crystals on a pocket calculator  

NASA Astrophysics Data System (ADS)

A generalization of the semiempirical microscopic model of hardness is presented and applied to currently studied borides, carbides, and nitrides of heavy transition metals. The hardness of OsB, OsC, OsN, PtN, RuC, RuB2 , ReB2 , OsB2 , IrN2 , PtN2 , and OsN2 crystals in various structural phases is predicted. It is found that none of the transition metal crystals is superhard, i.e., with hardness greater than 40GPa . The presented method provides materials researchers with a practical tool in the search for new hard materials.

Šim?nek, Antonín

2007-05-01

370

Pseudo hard-sphere potential for use in continuous molecular-dynamics simulation of spherical and chain molecules  

NASA Astrophysics Data System (ADS)

We present a continuous pseudo-hard-sphere potential based on a cut-and-shifted Mie (generalized Lennard-Jones) potential with exponents (50, 49). Using this potential one can mimic the volumetric, structural, and dynamic properties of the discontinuous hard-sphere potential over the whole fluid range. The continuous pseudo potential has the advantage that it may be incorporated directly into off-the-shelf molecular-dynamics code, allowing the user to capitalise on existing hardware and software advances. Simulation results for the compressibility factor of the fluid and solid phases of our pseudo hard spheres are presented and compared both to the Carnahan-Starling equation of state of the fluid and published data, the differences being indistinguishable within simulation uncertainty. The specific form of the potential is employed to simulate flexible chains formed from these pseudo hard spheres at contact (pearl-necklace model) for mc = 4, 5, 7, 8, 16, 20, 100, 201, and 500 monomer segments. The compressibility factor of the chains per unit of monomer, mc, approaches a limiting value at reasonably small values, mc < 50, as predicted by Wertheim's first order thermodynamic perturbation theory. Simulation results are also presented for highly asymmetric mixtures of pseudo hard spheres, with diameter ratios of 3:1, 5:1, 20:1 over the whole composition range.

Jover, J.; Haslam, A. J.; Galindo, A.; Jackson, G.; Müller, E. A.

2012-10-01

371

Gill surface interaction model for trace-metal toxicity to fishes: role of complexation, pH, and water hardness  

Microsoft Academic Search

A model has been developed to account for the variability in trace-metal toxicity to fishes at different values of alkalinity, hardness, and pH. The model utilizes trace-metal speciation, gill surface interaction, and competitive inhibition to predict effective, toxicant concentration (ETC). Copper, cadmium, lead, and zinc bioassay data have been utilized.

Gordon K. Pagenkopf

1983-01-01

372

Using fundamental measure theory to treat the correlation function of the inhomogeneous hard-sphere fluid.  

PubMed

We investigate the value of the correlation function of an inhomogeneous hard-sphere fluid at contact. This quantity plays a critical role in statistical associating fluid theory, which is the basis of a number of recently developed classical density functionals. We define two averaged values for the correlation function at contact and derive formulas for each of them from the White Bear version of the fundamental measure theory functional, using an assumption of thermodynamic consistency. We test these formulas, as well as two existing formulas, against Monte Carlo simulations and find excellent agreement between the Monte Carlo data and one of our averaged correlation functions. PMID:23367925

Schulte, Jeff B; Kreitzberg, Patrick A; Haglund, Chris V; Roundy, David

2012-12-28

373

Effects of food-simulating liquids on surface properties of giomer restoratives.  

PubMed

This study examined the effects of food-simulating liquid (FSL) on the hardness and roughness of giomer restoratives based on pre-reacted glass ionomer (PRG) technology. The materials investigated included a regular (Beautifil II [BT]) and a recently introduced injectable (Beautifil Flow Plus F00 [BF]) hybrid PRG composite. A direct hybrid composite (Filtek Z250 [ZT]) and an indirect hybrid composite (Ceramage [CM]) were used for comparison. The materials were placed into customized square molds (5 mm × 5 mm × 2.5 mm), covered with Mylar strips, and cured according to manufacturers' instructions. The materials were then conditioned in air (control), distilled water, 50% ethanol solution, and 0.02 N citric acid at 37°C for seven days. Specimens (n=6) were then subjected to hardness testing (Knoop) and surface profilometry. Data were analyzed using one-way analysis of variance and post hoc Scheffe test (p<0.05). Mean Knoop hardness values for the control group (air) ranged from 53.4 ± 3.4 (BF) to 89.5 ± 5.2 (ZT), while mean surface roughness values values ranged from 0.014 ± 0.002 (ZT) to 0.032 ± 0.001 (BT). All materials were significantly softened by FSL. The degree of softening by the different FSLs was material dependent. The hardness of giomers was most affected by citric acid and ethanol. The smoothest surface was generally observed with the control group. Giomer restoratives were significantly roughened by citric acid. PMID:22663197

Kooi, T J M; Tan, Q Z; Yap, A U J; Guo, W; Tay, K J; Soh, M S

2012-06-04

374

The use of the durometer to measure rock hardness in geomorphology. Advantages and limitations.  

NASA Astrophysics Data System (ADS)

The durometer is a hardness tester developed to measure hardness of metallic materials that has been recently introduced to measure rock hardness in weathering studies. Aoki & Matsukura (2007) highlight some advantages of the durometer compared with the Schmidt Rock Test Hammer: the smaller plunge allows measurements in small surfaces such as taffoni or rock carvings, the wider measurement range and the lower impact energy. This last makes it a non destructive method that can be used on relatively soft rocks. In this work the durometer Equotip (©) has been tested in different environments in the field and in the laboratory to explore its applicability and limitations. We applied the device on small rock samples of granite and limestone and a T-test showed that smaller sample size gave smaller hardness values (p < 0.01). Testing the effects of water content, there were no statistically significant differences between water saturated and dry samples. The influence of rock surface roughness was evaluated applying the durometer in ancient rock carvings in medium to coarse grain granites. We compared the values obtained inside and outside the grooves of the carvings using two different support rings, one flat and one concave. The flat ring was not able to reach the bottom of the groove, meanwhile the concave ring adjusts fairly well given its semi spherical section. A t-test confirmed the difference (p < 0.01) between lower rebound values obtained in the grooves using the flat ring and the higher and less scattered values obtained when the concave ring is used. As a very sensitive device, there are some problems in the use related with rock roughness and rock grain size. In weathered medium to coarse grained rocks, with very irregular surfaces, is not easy to get a good contact between the plunge and the rock surface. A poor contact caused by surface roughness causes the scattering and lowering of rebound values. On the contrary, in homogeneous fine grained rocks and in uniform rock surfaces the device gave very good results. The data obtained in glacial, nival and rock coastal environments showed the potential of the device in the identification of changes in rock hardness. We were able to asses the changes in the weathering degree of glacial striations and marked differences in the rock surfaces subjected or not to abrasion. A. Feal-Pérez is supported by the grant AP2006-03854 (Spanish Ministry of Education)

Feal-Pérez, Alejandra; Blanco-Chao, Ramón; Valcarcel-Díaz, Marcos; Combes, Martín. A.

2010-05-01

375

Exploring Existence Value  

NASA Astrophysics Data System (ADS)

The notion that individuals value the preservation of water resources independent of their own use of these resources is discussed. Issues in defining this value, termed "existence value," are explored. Economic models are employed to assess the role of existence value in benefit-cost analysis. The motives underlying existence value are shown to matter to contingent valuation measurement of existence benefits. A stylized contingent valuation experiment is used to study nonusers' attitudes regarding projects to improve water quality in the Chesapeake Bay. Survey results indicate that altruism is one of the motives underlying existence value and that goods other than environmental and natural resources may provide existence benefits.

Madariaga, Bruce; McConnell, Kenneth E.

1987-05-01

376

Implementing value strategy through the value chain  

Microsoft Academic Search

This article is a corollary to three articles published earlier in Management Decision. More precise definitions of a modern value chain are proposed, in terms of it being a business system that creates end-user satisfaction and realises the objectives of other member stakeholders. Comparisons are drawn with the current notion of supply chain management and an explanation is given as

David Walters; Geoff Lancaster

2000-01-01

377

Influence of plastic deformation upon the half-width of engineering metallic materials in hard state  

SciTech Connect

The half-width values of the X-ray diffract profiles are frequently used to characterize the static strength of a strengthened surface, or the depth distribution of this mechanical parameter, in a strengthened surface layer, especially in a shot-peening affected layer. However, for the unpeened surface and the base material of the shot-peened specimen of an alloy steel treated in hard state, the experimental results shown in this article indicate that uniaxial tensile or compressive plastic deformation increases the yield strengths while it decreases the half-width values. The half-width values of the shot-peened surface and surface layer greatly decrease, whereas the yield strength of this surface remarkably increases. Accordingly, in the authors` opinion, the half-width values could not correctly describe the static strengths of hard metallic materials, and, contrary to the viewpoint put forward by a lot of researchers, the shot-peened surfaces of such materials are work hardened instead of work softened. A model demonstrating that plastic deformation reduces the half-width values by decreasing the second kind internal stresses is developed.

Li, J.B.; Xu, H.B.; Chen, R.; Wang, Z.G. [Academia Sinica, Shenyang (China). State Key Lab. for Fatigue and Fracture of Materials

1996-11-01

378

36 CFR 13.1308 - Harding Icefield Trail.  

Code of Federal Regulations, 2013 CFR

... § 13.1308 Harding Icefield Trail. The Harding Icefield Trail from the junction with the main paved trail near Exit Glacier to the emergency hut near the terminus is closed toâ (a) Camping within 1/8 mile of the trail from March 1...

2013-07-01

379

Hardness measurement at penetration depths as small as 20 nm  

Microsoft Academic Search

In this paper we investigate the properties of indentation hardness on the sub-micrometre scale in nickel, gold and silicon. Indenter penetration depths as low as 20 nm are used. The area of the indents is determined by electron microscopy, and thus the Meyer hardness calculated. The indenter penetration is monitored continuously during loading and unloading. We show that indent areas,

J. B. Pethicai; R. Hutchings; W. C. Oliver

1983-01-01

380

Injury risk associated with ground hardness in junior cricket  

Microsoft Academic Search

To establish if there is an association between ground hardness and injury risk in junior cricket. Nested case-series of players who played matches on specific grounds with objective ground hardness measures, within a prospective cohort study of junior community club cricket players. Monitoring of injuries and playing exposure occurred during 434 matches over the 2007\\/2008 playing season. Objective assessment of

Dara M. Twomey; Peta E. White; Caroline F. Finch

381

DieHard: probabilistic memory safety for unsafe languages  

Microsoft Academic Search

Applications written in unsafe languages like C and C++ are vul- nerable to memory errors such as buffer overflows, dangling point- ers, and reads of uninitialized data. Such errors can lead to pro- gram crashes, security vulnerabilities, and unpredictable behavior. We present DieHard, a runtime system that tolerates these errors while probabilistically maintaining soundness. DieHard uses ran- domization and replication

Emery D. Berger; Benjamin G. Zorn

2006-01-01

382

Material hardness and ageing measurement using guided ultrasonic waves.  

PubMed

Elastic properties of materials can be easily determined from the ultrasonic wave velocity measurement. However, material hardness cannot be obtained from the ultrasonic wave speed. Heat treatment and ageing affect the microstructure of many materials changing their hardness and strength. It has been already established that ultrasonic attenuation and dispersion are also affected by the material microstructure. It is investigated in this paper if the attenuation of ultrasonic guided waves can be correlated with the material ageing or duration of heat treatment and material hardness. To this aim six identical aluminum 2024 alloy plate specimens were subjected to different durations of heat treatment at 150°C and were inspected nondestructively propagating Lamb waves through the specimens. Attenuation of the Lamb wave was found to be inversely related to the hardness. Rockwell hardness test was performed to corroborate the ultrasonic observations. In comparison to the Rockwell hardness test the ultrasonic inspection was found to be more sensitive to the heat treatment duration and material ageing. From these results it is concluded that guided wave inspection method is a reliable and probably more desirable alternative for characterizing the hardness and microstructure of heat treated materials. Earlier investigations correlated the bulk wave attenuation with the material ageing while this work is the first attempt to correlate the guided wave attenuation to the material hardness and ageing. PMID:23047018

Korde, Nilesh; Kundu, Tribikram

2012-09-18

383

A new design of hard X-ray polarimeter  

Microsoft Academic Search

A new type of polarimeter has been designed to detect polarized hard X-rays from stellar objects. The performance is investigated by computer simulations based on the characteristics of the polarimeter. The simulations show that the minimum detectable polarization of the hard X-rays from the Crab Nebula is about 13% for balloon observation over two hours. The authors report the design

S. Gunji; H. Sakurai; M. Noma; E. Takase; T. Saito; H. Misawa

1994-01-01

384

Puroindolines: the molecular genetic basis of wheat grain hardness  

Microsoft Academic Search

The variation in grain hardness is the single most important trait that determines end-use quality of wheat. Grain texture classification is based primarily on either the resistance of kernels to crushing or the particle size distribution of ground grain or flour. Recently, the molecular genetic basis of grain hardness has become known, and it is the focus of this review.

Craig F. Morris

2002-01-01

385

Proceedings of the Tungsten Workshop for Hard Target Weapons Program  

Microsoft Academic Search

The purpose of this meeting was to review and exchange information and provide technical input for improving technologies relevant to the Hard Target Weapons Program. This workshop was attended by representatives from 17 organizations, including 4 Department of Defense (DoD) agencies, 8 industrial companies, and 5 laboratories within DOE. Hard targets are defined as reinforced underground structures that house enemy

G. Mackiewicz-Ludtka; H. W. Hayden; R. M. Davis

1995-01-01

386

Equilibrium of drops (bubbles) on an oblique hard body surface  

NASA Astrophysics Data System (ADS)

A form of the energy functional is proposed which describes the equilibrium state of drops (bubbles) on an oblique hard body surface. Conditions are obtained for the loss of the stable equilibrium of drops (bubbles) on the oblique surface of a hard body with a dimensionless diameter D/a of 2 or less. The results obtained are compared with data in the literature.

Popov, V. G.

1990-10-01

387

Attachment strategies of organisms on hard substrates: A palaeontological view  

Microsoft Academic Search

Attached organisms on hard substrates have been termed sessile, fixed, encrusting, cemented. These terms reflect the palaeontological aspect of these communities, the securely fixed organisms having the best taphonomic chances of surviving fossilization in life position. Neontologists commonly refer to organisms attached to hard substrates as “fouling organisms”. However, there are numerous other styles of attachment that are characteristic of

Richard G. Bromley; Claus Heinberg

2006-01-01

388

Dough Rheology and Wet Milling of Hard Waxy Wheat Flours  

Technology Transfer Automated Retrieval System (TEKTRAN)

To realize the full potential of waxy wheat (Triticum aestivum L.), wet milling of waxy wheat flour to produce gluten and waxy wheat starch was investigated. Flours of six advanced lines of waxy hard wheats, one normal hard wheat (‘Karl 92’), and one partial waxy wheat (‘Trego’) were fractionated by...

389

Groundwater numerical simulation of total hardness in Beijing suburb  

Microsoft Academic Search

Basing on groundwater quality data collected in Beijing and groundwater chemical characteristic, the paper studies the hydrogeochemistry law of groundwater total hardness of Beijing suburb in some methods such as groundwater solute transportation simulation and the geological statistics. Set up hydrogeology conception model, mathematic model and the three-dimensional groundwater total hardness transportation model. At last, the paper forecasts evolution trend

Yu Guoqing; Chu Haibo; Yang Leilei

2011-01-01

390

Phase behavior of hard colloidal platelets using free energy calculations  

Microsoft Academic Search

We investigate the phase behavior of a model for colloidal hard platelets and rigid discotic molecules: oblate hard spherocylinders (OHSC). We perform free energy calculations using Monte Carlo simulations to map out the phase diagram as a function of the aspect ratio L\\/D of the particles. The phase diagram displays a stable isotropic phase, a nematic liquid crystal phase for

Matthieu Marechal; Alejandro Cuetos; Bruno Martínez-Haya; Marjolein Dijkstra

2011-01-01

391

Carbon hard masks for etching sub-90 nm structures  

Microsoft Academic Search

Carbon hard mask structures have been used to etch a variety of materials typically used in sub 90nm DRAM manufacture. The results indicate that carbon hard masks can be used very effectively to structure oxide, nitride and metal films giving the CD performance required for the technologies being investigated.

Kevin A. Pears; Momtchil Stavrev; Alessia Scire; Ralf Koepe; Matthias Markert; Ulrich Egger; Lee Donohue

2005-01-01

392

Thermal modeling for white layer predictions in finish hard turning  

Microsoft Academic Search

Part thermal damage is a process limitation in finish hard turning and understanding process parameter effects, especially, tool wear, on cutting temperatures is fundamental for process modeling and optimization. This study develops an analytical model for cutting temperature predictions, in particular, at the machined-surfaces, in finish hard turning by either a new or worn tool.A mechanistic model is employed to

Y. Kevin Chou; Hui Song

2005-01-01

393

Hardness Analysis. Training Module 5.215.2.77.  

ERIC Educational Resources Information Center

This document is an instructional module package prepared in objective form for use by an instructor familiar with hardness analysis using the EDTA method and the calculation of hardness given metal ion concentrations and a factor table. Included are objectives, an instructor guide, student handouts, and transparency masters. A video tape is also…

Bonte, John L.; Davidson, Arnold C.

394

Fractography of critical and subcritical cracks in hard materials  

Microsoft Academic Search

In testing hard and brittle materials like hard metals and ceramics for fracture resistance, stable and unstable crack propagation can be observed. The question arises if critical and subcritical cracks proceed in the same way, and, as a corollary, if results from subcritical fracture can be used to describe catastrophic failure. Results from earlier work are re-evaluated to demonstrate the

H. E. Exner; L. Sigl; M. Fripan; O. Pompe

2001-01-01

395

Hard chromium plating of EDT mill work rolls  

Microsoft Academic Search

Hard chromium plating of cold mill work rolls is common practice in order to maintain topography and increase roll service life. The paper details the effect of hard chromium plating on electrical discharge textured (EDT) roll surface topography and surface integrity. Comparative data with corresponding non-chromium plated EDT roll samples are also presented and discussed. Irrespective of the EDT roll

J Simão; D. K Aspinwall

1999-01-01

396

The implications of food hardness for diet in bats  

Microsoft Academic Search

Summary 1. Neotropical bat communities are characterized by a broad species diversity, which can be achieved and maintained only through partitioning of the available resources. 2. Here patterns of trophic resource utilization within a single neotropical savanna bat community are investigated. Moreover, the physical properties of food items (i.e. hardness), its variation with food size, and whether food hardness differs

L. F. Aguirre; A. Herrel; R. Van Damme; E. MatThysen

2003-01-01

397

Chemical bonding in hard boron-nitride multilayers.  

National Technical Information Service (NTIS)

The oxides and nitrides of boron show great potential for use as hard, wear resistant materials. However, large intrinsic stresses and poor adhesion often accompany the hard coatings as found for the cubic boron-nitride phase. These effects may be moderat...

A. F. Jankowski J. P. Hayes

1997-01-01

398

Modeling of Residual Stress Profile in Finish Hard Turning  

Microsoft Academic Search

Mechanical components shaped by hard turning processes are commonly used under high stress and repeated loading conditions. The physical strength and fatigue life of these components is known to be significantly affected by the residual stress distributions induced by finish hard turning. A thorough understanding of the residual stress profile including both magnitude and direction along the depth of the

Jing Ying Zhang; Steven Y. Liang; Guowei Zhang; David Yen

2006-01-01

399

Calcium nephrolithiasis: effect of water hardness on urinary electrolytes  

Microsoft Academic Search

Objectives. To analyze the impact of water hardness from public water supplies on calcium stone incidence and 24-hour urine chemistries in patients with known calcium urinary stone formation. Patients are frequently concerned that their public water supply may contribute to urinary stone disease. Investigators have documented an inverse relationship between water hardness and calcium lithogenesis. Others have found no such

Bradley F Schwartz; Noah S Schenkman; Jeremy E Bruce; Stephen W Leslie; Marshall L Stoller

2002-01-01

400

Changes in Water Hardness Influence Colonization of Saprolegnia diclina  

Microsoft Academic Search

Experiments were conducted to determine the effects of different water hardness concentrations on colonization of Saprolegnia diclina in an attempt to explain some of the differences in fungal growth and antifungal chemical effectiveness observed at various fish hatcheries. Fungal growth on nonviable seeds of hemp Cannabis sativa was observed significantly sooner in water where hardness was elevated due to the

Michael E. Barnes; Audrey C. Gabel; Dan J. Durben; Timothy R. Hightower; Tate J. Berger

2004-01-01

401

“Corriendo”: Hard Boundaries, Human Rights and the Undocumented Immigrant  

Microsoft Academic Search

This article takes a critical look at the question of whether hard international boundaries that prevent migration can be justified from an ethical standpoint, or whether these hard boundaries represent a violation of human rights. The question is first addressed from a theoretical perspective, drawing on theories of justice and of boundaries. The article then examines policy decisions and the

Martha Scarpellino

2007-01-01

402

HARD RED SPRING WHEAT QUALITY REPORT: 2000/2001 CROP.  

Technology Transfer Automated Retrieval System (TEKTRAN)

Commercially grown cultivars and experimental lines of hard red spring wheat were grown by breeders at cooperative experiment stations throughout the major spring wheat growing regions of the United States. Hard spring wheat was tested for kernel, milling, flour, dough, and baking quality. In 2000...

403

Values and Public Dissent.  

National Technical Information Service (NTIS)

Using a factor-scales instrument, an index of values developed in previous pilot studies that supplies 12 scores, respondents from dissenting and defending groups were surveyed. The value scales measured approval-disapproval of decisive leadership, respon...

F. K. Berrien

1971-01-01

404

Values: Lest We Forget.  

National Technical Information Service (NTIS)

This paper examines the Army's individual values of courage, commitment, competence and candor. Each value is examined and further defined through the use of historical vignettes, anecdotes, quotations and interviews. This discussion is followed by sectio...

G. T. Greco

1993-01-01

405

Crop Values. 2008 Summary.  

National Technical Information Service (NTIS)

Crop Values includes average prices and values of production for major field crops and many specialty crops. All prices in this report are marketing year average (MYA) prices which do not include allowances or adjustments for commodities under government ...

2009-01-01

406

Crop Values. 2009 Summary.  

National Technical Information Service (NTIS)

Crop Values includes average prices and values of production for major field crops and many specialty crops. All prices in this report are marketing year average (MYA) prices which do not include allowances or adjustments for commodities under government ...

2010-01-01

407

Crop Values. 2007 Summary.  

National Technical Information Service (NTIS)

The 2007 'Crop Values' includes average prices and values of production for major field crops and many specialty crops. All prices in this report are marketing year average (MYA) prices which do not include allowances or adjustments for commodities under ...

2008-01-01

408

On the stiffness of materials containing a disordered array of microscopic holes or hard inclusions  

NASA Astrophysics Data System (ADS)

We study the macroscopic mechanical behavior of materials with microscopic holes or hard inclusions. Specifically, we deal with the effective elastic moduli of composites whose microgeometry consists of either soft or hard isolated inclusions surrounded by an elastic matrix. We approach this problem by taking the stiffness of the inclusion phase to be a complex variable, which we eventually evaluate at the soft or hard limits. Our main result states that there is a certain class of non-physical, negative-definite values of the elastic moduli of the inclusion phase for which the effective tensor does not have infinities or become otherwise singular.We present applications of this result to the estimation of effective moduli and to homogenization theorems. The first application involves using complexanalytic methods to obtain rigorous and accurate bounds on the effective moduli of the high-contrast composites under consideration. We also discuss the variational estimates of Rubenfeld & Keller, which yield a complementary set of bounds on these moduli. The best bounds are given by a combination of the analytical and variational results. As a second application, we show that certain known theorems of homogenization for materials with holes are simple consequences of our main result, and in this connection we establish corresponding new theorems for materials with hard inclusions. While our rederivation of the homogenization theorems for materials with holes can be closely related to other known constructions, it appears that certain elements provided by our main result are essential in the proof of homogenization for the hard-inclusion case.

Bruno, Oscar P.; Leo, Perry H.

1992-12-01

409

Influence of water hardness and sulfate on the acute toxicity of chloride to sensitive freshwater invertebrates.  

PubMed

Total dissolved solids (TDS) represent the sum of all common ions (e.g., Na, K, Ca, Mg, chloride, sulfate, and bicarbonate) in freshwater. Currently, no federal water quality criteria exist for the protection of aquatic life for TDS, but because the constituents that constitute TDS are variable, the development of aquatic life criteria for specific ions is more practical than development of aquatic life criteria for TDS. Chloride is one such ion for which aquatic life criteria exist; however, the current aquatic life criteria dataset for chloride is more than 20 years old. Therefore, additional toxicity tests were conducted in the current study to confirm the acute toxicity of chloride to several potentially sensitive invertebrates: water flea (Ceriodaphnia dubia), fingernail clams (Sphaerium simile and Musculium transversum), snail (Gyraulus parvus), and worm (Tubifex tubifex), and determine the extent to which hardness and sulfate modify chloride toxicity. The results indicated a significant ameliorating effect of water hardness (calcium and magnesium) on chloride toxicity for all species tested except the snail; for example, the 48-h chloride median lethal concentration (LC50) for C. dubia at 50?mg/L hardness (977?mg Cl(-) /L) was half that at 800?mg/L hardness (1,836?mg Cl(-) /L). Conversely, sulfate over the range of 25 to 600?mg/L exerted a negligible effect on chloride toxicity to C. dubia. Rank order of LC50 values for chloride at a given water hardness was in the order (lowest to highest): S. simile?

Soucek, David J; Linton, Tyler K; Tarr, Christopher D; Dickinson, Amy; Wickramanayake, Nilesh; Delos, Charles G; Cruz, Luis A

2011-02-11

410

Temperature rise during intraoral polymerization of self-cured hard denture base liners.  

PubMed

The aim of this in-vivo study was to evaluate the temperature rise during polymerization of five chairside self-cured hard denture base reliners. For the same patient, 30 identical baseplates, exposing a space on their tissue surface to accommodate the lining material, were made of a light-cured denture base material. A hole was drilled in the center of this area to enable the thermocouple wire of the temperature measuring device to have direct access to the palatal surface of the baseplate. Six baseplates were used for each of the five lining materials tested. Temperature recordings were made every 15 seconds. Data were analyzed using single factor analysis of variance (ANOVA) and the Scheffe's post-hoc analysis for multiple comparisons. The mean maximum temperature values ranged from 40.2 degrees C to 45.7 degrees C being statistically different among the materials (P<0.001). The maximum peak temperature was 53 degrees C and the lowest 39 degrees C. Also the difference between the time each material reached the peak of temperature was statistically significant (P<0.0001). A temperature range of 5.5 degrees C was demonstrated among materials, with the highest polymerization temperatures recorded for Flexacryl Hard and the lowest for Rebase and GC Reline hard. Ufi-gel hard showed the fastest polymerization cycle and was the first to reach the maximum temperature. The available chairside hard liners must be chosen with care considering the thermal effect on the oral mucosa and the discomfort of patient. PMID:20698423

Yannikakis, Stavros; Polychronakis, Nick; Zissis, Alcibiades

2010-06-01

411

The values of life.  

PubMed

In Life's Dominion Dworkin aims at defusing the controversy about abortion and euthanasia by redefining its terms. Basically it is not a dispute about the right to life, but about its value. Liberals should grant that human life has not only a personal, but also an intrinsic value; conservatives should accept the principle of toleration which requires to let people decide for themselves about matters of intrinsic value. Dworkin fails, however, to distinguish between two kinds of personal value: (1) the value of something to a person, when he actually or dispositionally desires it, or finds it pleasant; and (2) the value of something to a person, when it's objectively contributes to his well-being, as defined by reference to his personal point of view, whether or not he ever perceives it as so contributing. He also fails to distinguish between two meanings of the concept of 'intrinsic value': (3) ultimate, i.e. non-instrumental personal value of kind (2); (4) the impersonal value of something which is not good-for-anybody, but simply good, i.e. not a constituent of someone's well-being. Dworkin argues that the human fetus from conception onwards has a value, that it is not a personal value of kind (1), and therefore must be an intrinsic value. But the value of the life of the fetus is not a personal value of kind (2) either and therefore not an intrinsic value of kind (3): it is normally a constituent of the well-being of the pregnant woman, but that doesn't constitute its value, and it is not good 'for' the fetus itself in the relevant sense, because it doesn't have a personal point of view. If, however, the fetus' life is allowed to have an intrinsic value of kind (4), the conservative cannot be refuted by appeal to the principle of toleration, for this only concerns intrinsic value of kind (3). The liberal, indeed, should recognize that the fetus' life has a value, but it is neither a personal value (1) or (2), nor an impersonal value (4), but rather a relational value which gradually develops from some point substantially later than conception. PMID:11656609

Den Hartogh, Govert

1997-01-01

412

Identifying Extreme Exposure Values  

Cancer.gov

There are various perspectives on whether to exclude potentially unlikely exposure values. If the researcher chooses to do so, several approaches exist for identifying extreme values. We examined the plausibility of the reported frequencies for each food item in the NHANES 2009-10 DSQ and chose to exclude extreme values using a method that identifies them based on the actual distribution of the sample, but also minimizes the number of values excluded.

413

Place Value Rocks!  

NSDL National Science Digital Library

Play these educational math games and test your knowledge of Place Value! Can you use Place Value Blocks to help you represent different digits? Test your ability to write out given numbers into sentences with Cookies! How sharp are your place value skills? Test your knowledge with Golfing with numbers!! Be the hero of the day as you practice place value skills in the Lifeguard game! Reveal the ...

Ms.roberts

2009-03-04

414

Deposition, structure, and hardness of polycrystalline transition-metal nitride superlattice films  

SciTech Connect

Polycrystalline TiN/VN, NbN/VN, and TiN/NbN superlattices with periods {Lambda} between 2 and 160 nm were deposited onto steel substrates using an opposed-cathode reactive magnetron sputtering system. The nitrogen partial pressure and the substrate bias values were optimized in order to obtain dense stoichiometric films, which yielded the highest Vickers hardnesses H{sub V}. H{sub V} for TiN/VN and TiN/NbN superlattices reached maximum values of {approx}5000 kgf/mm{sup 2} at {Lambda}{approx}5{endash}10&hthinsp;nm, compared with {approx}2000 kgf/mm{sup 2} for homogeneous TiN, NbN, and VN films. In contrast, H{sub V}{approx}2000&hthinsp;kgf/mm{sup 2} was obtained for VN/NbN superlattices independent of {Lambda}. Model calculations in which the hardness enhancement was proportional to the difference in layer shear moduli gave good agreement with the data. The lack of hardness enhancement in VN/NbN indicates that any other hardening mechanisms, such as coherency strains and dislocation blocking by interfacial misfit dislocations, were not important. {copyright} {ital 1999 Materials Research Society.}

Chu, X.; Wong, M.S.; Sproul, W.D.; Barnett, S.A. [Department of Materials Science and Engineering and the Advanced Coating Technology Group, Northwestern University, Evanston, Illinois 60208 (United States)

1999-06-01

415

Hardness variation with indenter sharpness in an Au thin-film.  

PubMed

The effects of the indenter shape on hardness were studied from thin-film nanoindentations. Two Berkovich indenters with different operating histories were prepared and their morphologies were measured with an atomic force microscope. The curvature radii of both indenters that were measured through an image analysis were 58.8 nm and 732.2 nm, respectively. The nanoindentations were carried out on a 1.2 microm-thick Au thin-film with a Nanoindenter XP system with both indenters. Various nanoindentation data with indenter exchanges were surveyed, and they showed that the peak indentation loads under the blunter indenter were higher than those of the sharper indenter at the same indentation depths. The indenter sharpness parameter was used to correct the raw nanoindentation curves. The corrected curves overlapped well and the resulting hardness values were consistent regardless of the indenter sharpness. The intrinsic hardness values of the Au thin-film from both indenters agreed with each other, with only a 0.6% difference. This means the indenter sharpness was properly corrected and that the sharpness must be considered when the contact properties are measured at shallow indentations. PMID:22966626

Lee, Yun-Hee; Kim, Yong-Il; Hahn, Jun-Hee

2012-07-01

416

Simulating asymmetric colloidal mixture with adhesive hard sphere model  

NASA Astrophysics Data System (ADS)

Monte Carlo simulation and Percus-Yevick (PY) theory are used to investigate the structural properties of a two-component system of the Baxter adhesive fluids with the size asymmetry of the particles of both components mimicking an asymmetric binary colloidal mixture. The radial distribution functions for all possible species pairs, g11(r), g22(r), and g12(r), exhibit discontinuities at the interparticle distances corresponding to certain combinations of n and m values (n and m being integers) in the sum n?1+m?2 (?1 and ?2 being the hard-core diameters of individual components) as a consequence of the impulse character of 1-1, 2-2, and 1-2 attractive interactions. In contrast to the PY theory, which predicts the delta function peaks in the shape of gij(r) only at the distances which are the multiple of the molecular sizes corresponding to different linear structures of successively connected particles, the simulation results reveal additional peaks at intermediate distances originating from the formation of rigid clusters of various geometries.

Jamnik, A.

2008-06-01

417

Debris-Bed Friction of Hard-Bedded Glaciers  

NASA Astrophysics Data System (ADS)

Field measurements of debris-bed friction on a smooth rock tablet at the bed of Engabreen, a hard-bedded, temperate glacier in northern Norway, indicated that basal ice containing 10% debris by volume exerted local shear traction of up to 500~kPa. The corresponding bulk friction coefficient between the dirty basal ice and the tablet was between 0.05 and 0.08. A model of friction in which non-rotating spherical rock particles are held in frictional contact with the bed by bed-normal ice flow can account for these measurements if ice is Newtonian. Numerical calculations of the bed-normal drag force on a sphere in contact with a flat bed show that this force can reach values several hundred times that on a sphere isolated from the bed, thus drastically increasing frictional resistance. Various estimates of basal friction are obtained from this model. For example, the shear traction at the bed of a 200~m thick glacier sliding at 20~m a-1 with a geothermally induced melt rate of 0.006~m a-1 can exceed 100~kPa. Debris-bed friction can, therefore, be a major component of sliding resistance, contradicting the common assumption that debris-bed friction is negligible.

Cohen, D.; Iverson, N. R.; Hooyer, T. S.; Fischer, U. H.; Jackson, M.; Moore, P. L.

2004-12-01

418

Debris-bed friction of hard-bedded glaciers  

NASA Astrophysics Data System (ADS)

Field measurements of debris-bed friction on a smooth rock tablet at the bed of Engabreen, a hard-bedded, temperate glacier in northern Norway, indicated that basal ice containing 10% debris by volume exerted local shear traction of up to 500 kPa. The corresponding bulk friction coefficient between the dirty basal ice and the tablet was between 0.05 and 0.08. A model of friction in which nonrotating spherical rock particles are held in frictional contact with the bed by bed-normal ice flow can account for these measurements if the power law exponent for ice flowing past large clasts is 1. A small exponent (n < 2) is likely because stresses in ice are small and flow is transient. Numerical calculations of the bed-normal drag force on a sphere in contact with a flat bed using n = 1 show that this force can reach values several hundred times that on a sphere isolated from the bed, thus drastically increasing frictional resistance. Various estimates of basal friction are obtained from this model. For example, the shear traction at the bed of a glacier sliding at 20 m a-1 with a geothermally induced melt rate of 0.006 m a-1 and an effective pressure of 300 kPa can exceed 100 kPa. Debris-bed friction can therefore be a major component of sliding resistance, contradicting the common assumption that debris-bed friction is negligible.

Cohen, D.; Iverson, N. R.; Hooyer, T. S.; Fischer, U. H.; Jackson, M.; Moore, P. L.

2005-06-01

419

Cavities in the hard sphere crystal and fluid  

NASA Astrophysics Data System (ADS)

The number, size, surface area and shape of cavities in the hard-sphere crystal and dense fluid were studied by simulation. The number nc of cavities per sphere is given over about 60 orders of magnitude by -ln{nc} = pV/NkT - 1 + F(z) with F(z) ? - 0·6 + ln {z} in the crystal and F(z) ? - 2·5 in the dense fluid. The average cavity volume is given by ln = ?S/Nk - ln{N/V} + F(z), where ?S is the entropy relative to an ideal gas. z is the density relative to close packing. The equilibrium number of vacancies per sphere in the crystal is nv = nc/(1·2z - 0·45). The cavity shape factor a(z), defined by pV/NkT = 1 + a(z)/1/3, is close to the sphere diameter ?. The assumption that a(z) ? ? predicts the measured values of , and nc, for the crystal, to within their uncertainties.

Bowles, Richard K.; Speedy, Robin J.

420

Fuzzy and hard clustering analysis for thyroid disease.  

PubMed

Thyroid hormones produced by the thyroid gland help regulation of the body's metabolism. A variety of methods have been proposed in the literature for thyroid disease classification. As far as we know, clustering techniques have not been used in thyroid diseases data set so far. This paper proposes a comparison between hard and fuzzy clustering algorithms for thyroid diseases data set in order to find the optimal number of clusters. Different scalar validity measures are used in comparing the performances of the proposed clustering systems. To demonstrate the performance of each algorithm, the feature values that represent thyroid disease are used as input for the system. Several runs are carried out and recorded with a different number of clusters being specified for each run (between 2 and 11), so as to establish the optimum number of clusters. To find the optimal number of clusters, the so-called elbow criterion is applied. The experimental results revealed that for all algorithms, the elbow was located at c=3. The clustering results for all algorithms are then visualized by the Sammon mapping method to find a low-dimensional (normally 2D or 3D) representation of a set of points distributed in a high dimensional pattern space. At the end of this study, some recommendations are formulated to improve determining the actual number of clusters present in the data set. PMID:23357404

Azar, Ahmad Taher; El-Said, Shaimaa Ahmed; Hassanien, Aboul Ella

2013-01-26

421

Expected Relationship Value  

Microsoft Academic Search

Managing collaborative business-to-business relationships demands an understanding of how relationships create value for the firm and a method to accurately assess that value. The purpose of this research is to propose a new construct, expected relationship value, and an innovative method for its measurement. The proposed methodology relies on qualitative research techniques to gather dispersed organizational knowledge about the relationship.

John E Hogan

2001-01-01

422

Summer Place Value  

NSDL National Science Digital Library

Play some fun games with your new place value skills Match the number words to the standard form to find the place value mystery picture. Can you solve the place value puzzler? Click on easy and follow the instructions. Check your score after the picture is shown. How many tries did it take you to be able to see the picture. If it ...

Korth, Mrs.

2009-07-27

423

Values and Creativity  

Microsoft Academic Search

Does extrinsic motivation inhibit or foster creativity? Whereas previous researchers examined the effects of externally controlled extrinsic motivation on creativity, we focus on the effects of self-determined extrinsic motivation arising from one's personally held core values. In this study, we present a theoretical argument which predicts that (a) creative behavior is fostered by certain value types, inhibited by other value

Joseph Kasof; Chuansheng Chen; Amy Himsel; Ellen Greenberger

2007-01-01

424

Emergy and Nonmarket Value  

EPA Science Inventory

The purpose of this study is to better understand the differences and similarities between emergy and nonmarket economic valuation, when both are applied to value the same policies or development alternatives. The emdollar value of a good or service often exceeds the market value...

425

Extrinsic Value Orientation and \\  

Microsoft Academic Search

Two studies examined the effect of Extrinsic Value Orientation (Kasser & Ryan, 1993, 1996) upon harvesting strategies and personal profit within commons dilemmas, in which individual and group interests can be at odds. At an individual or within-group level of analysis, extrinsically oriented persons (who value money, fame, and popularity) harvested more than intrinsi- cally oriented persons (who value self-acceptance,

Kennon M. Sheldon; Holly A. McGregor

2000-01-01

426

Values and female entrepreneurship  

Microsoft Academic Search

Purpose – The purpose of this paper is to research the extent to which different types of values influence a woman's decision to become an entrepreneur. Design\\/methodology\\/approach – The paper constructs a two-stage model to capture the entrepreneurial decision. In the first stage, life values affect the decision to enter the workforce. In the second stage, work values impact the

Katherine Terrell; Michael Troilo

2010-01-01

427

59 FR- Value Engineering  

Federal Register 2010, 2011, 2012, 2013

...No. 94-12] RIN 2125-AD33 Value Engineering AGENCY: Federal Highway Administration...proposes to issue a regulation on value engineering (VE) that would require its application...the Secretary may require a value engineering or other cost reduction analysis...

1994-11-16

428

Many-Valued Logics  

Microsoft Academic Search

The paper considers the fundamental notions of many- valued logic together with some of the main trends of the recent development of inflnite valued systems, often called mathematical fuzzy logics. Besides this logical approach also a more algebraic approach is discussed. And the paper ends with some hints toward applications which are based upon actual theoretical considerations about inflnite valued

Siegfried Gottwald

429

Globalisation and Values  

Microsoft Academic Search

This paper discusses a central element in globalisation debate little addressed by economists, namely the interactions at global, national and community levels between globalisation and societally based values. Social values refer to wider notions of collective identity; religious values, attitudes towards materialism, moral beliefs, and a sense of collective awareness and are a broader and more encompassing concept than social

John Whalley

2008-01-01

430

Globalization and Values  

Microsoft Academic Search

This paper discusses a central element in globalization debate little addressed by economists, namely the interactions at global, national, and community levels between globalization and societally based values. Social values refer to wider notions of collective identity: religious values, attitudes towards materialism, moral beliefs, and a sense of collective awareness and are a broader and more encompassing concept than social

John Whalley

2005-01-01

431

Reframing Sacred Values  

Microsoft Academic Search

Sacred values differ from material or instrumental values in that they incorporate moral beliefs that drive action in ways dissociated from prospects for success. Across the world, people believe that devotion to essential or core values – such as the welfare of their family and country, or their commitment to religion, honor, and justice – are, or ought to be,

Scott Atran; Robert Axelrod

2008-01-01

432

A Rockwell hardness test for portland cement concrete  

NASA Astrophysics Data System (ADS)

The ASTM standard Superficial Rockwell hardness test using a 1/2 inch ball indenter and a 15 kgf Major Loar (15Y test) were adapted to perform nondestructive hardness tests on portland cement mortars and concrete. Correlations between the compressive strength of both materials and their hardnesses were found. The correlation for normal concrete and 3 x 6 inches compression cylinders is: 15Y hardness = 73.5 x (log compressive strength in psi) - 187 and has a correlation coefficient of 88 percent. The test can be performed on samples as thin as 2 mm, on surfaces with a radius of curvature no less than 2 cm and as close to a sample edge as 1 mm. The test uses a standard Rockwell Superficial hardness test instrument but requires a tungsten carbide indenting ball and a sufficiently large sample support to hold the size sample that is being tested.

Winslow, D. N.

1981-07-01

433

Surface Integrity of Hard Metal Parts Machined by WEDM  

NASA Astrophysics Data System (ADS)

Hard metal is characterised by having a extremely high hardness and high wear resistance, and those characteristics make difficult conventional machining. Electrical Discharge Machining (EDM) has become an attractive and feasible method for the manufacturing of precision hard metal tooling, and it is now an alternative to classical diamond grinding. This is due to the thermal nature of material removal mechanism in EDM, which is therefore independent on part hardness. This work pays attention to the analysis of surface integrity in wire EDM'ed hard metal parts. Damages on the machined surfaces have been characterised for different cutting regimes. Special attention has been paid to the heat affected zone, since it is in this zone where cracking mostly occurs. The study includes the analysis of the chemical composition of the affected layers. Additionally, the influence of successive trim cuts on surface roughness is addressed.

Plaza, S.; Izquierdo, B.; Sanchez, J. A.; Ortega, N.; Ramos, J. M.

2009-11-01

434

The Hard X ray Telescope Mission  

NASA Astrophysics Data System (ADS)

The Hard X Ray Telescope (HXT) was selected for study as a possible new intermediate size mission for the early 21st century. Its principal attributes are: (1) multiwavelength observing with a system of focussing telescopes that collectively observe from the UV to over 1 MeV, (2) much higher sensitivity and much better angular resolution in the 10100 keV band, and (3) higher sensitivity for detecting gamma ray lines of known energy in the 100 keV to 1 MeV band. The institutions collaborating in the study are: Smithsonian Astrophysical Observatory, Marshall Space Flight Center, Naval Research Laboratory, Goddard Space Flight Center, Argonne National Laboratory, Danish Space Research Institute, Osservatorio Astronomica di Brera (Merate), and Centre d'Etudes Spatiale des Rayonnements (Toulouse). The instrumentation includes several grazing incidence double conical telescopes with multilayer coatings that focus up to 100 keV and a single Laue crystal telescope that functions to 1 MeV. The detectors are CCDs, and germanium, and/or CdZnTe position sensitive arrays.

Gorenstein, Paul

1997-01-01

435

Depletion Interactions among Hard Spheres inside Vesicles  

NASA Astrophysics Data System (ADS)

We demonstrate that hard spheres diffusing inside a rigid vesicle of complex shape are pushed by entropic excluded-volume interactions to the surface of the vesicle and pushed along the vesicle's surface in the direction of increasing curvature(A.D. Dinsmore, A.G. Yodh and D.J. Pine, Nature 383), 239 (1996).. Rigid, multilamellar SOPC vesicles (3 ?m in diameter) contained water, polystyrene spheres and enough salt to screen out long-range electrostatic interactions. A lone 0.47-?m diameter sphere diffused freely inside the vesicle. When smaller spheres (0.08 ?m, volume fraction = 0.3) were present, the free energy of the mixture decreased by ? kT as the larger sphere moved from bulk to flat surface, and further decreased by kT as it moved from a flat surface to a curved region of the surface. The force will be explained within the depletion-force model by considering the volume accessible to the small spheres as a function of large-sphere position and surface shape. The possibility of membrane curvature induced by the particles will be discussed. Supported by NSF Grant No. DMR93-06814 and Materials Research Grant No. DMR91-20668. AGY also supported in part by the NSF PYI program and by the Alfred P. Sloan Foundation.

Dinsmore, A. D.; Wong, D. T.; Yodh, A. G.

1997-03-01

436

Stacking in sediments of colloidal hard spheres.  

PubMed

We use computer simulations to investigate the crystallization dynamics of sedimenting hard spheres in large systems (hundreds of thousands of particles). We show that slow sedimentation results primarily in face-centered cubic (fcc) stacked crystals, instead of random hexagonal close packed or hexagonal close packed (hcp) crystals. We also find slanted stacking faults, in the fcc regions. However, we attribute the formation of fcc to the free energy difference between fcc and hcp and not to the presence of these slanted stacking faults. Although the free energy difference between hcp and fcc per particle is small (only 10(-3) times the thermal energy), it can become considerable, when multiplied by the number of particles in each domain. The ratio of fcc to hcp obtained from dynamic simulations is in excellent agreement with well-equilibrated Monte Carlo simulations, in which no slanted stacking faults were found. Our results explain a range of experiments on colloids, in which the amount of fcc increases upon lowering the sedimentation rate or decreasing the initial volume fraction. PMID:21787016

Marechal, Matthieu; Hermes, Michiel; Dijkstra, Marjolein

2011-07-21

437

Hard X-ray Footpoint Source Sizes  

NASA Astrophysics Data System (ADS)

RHESSI has detected compact hard (25 - 100 keV) X-ray sources that are ? arcseconds (FWHM) in extent for certain flares (Dennis and Pernak (2009). These sources are believed to be at magnetic loop footpoints that are known from observations at other wavelengths to be very small. Flare ribbons seen in the UV with TRACE, for example, are 1 arcsecond in width, and white light flares show structure at the 1 arcsecond level. However, Kontar and Jeffrey (2010) have shown that the measured extent should be >6 arcseconds, even if the X-ray emitting thick-target source is point-like. This is because of the strong albedo contribution in the measured energy range for a source located at the expected altitude of 1 Mm near the top of the chromosphere. This discrepancy between observations and model predictions may indicate that the source altitude is significantly lower than assumed or that the RHESSI image reconstruction procedures are not sensitive to the more diffuse albedo patch in the presence of a strong compact source. Results will be presented exploring the latter possibility using the Pixon image reconstruction procedure and other methods based on visibilities. Dennis, B. R. and Pernak, R. L., 2009, ApJ, 698, 2131-2143. Kontar, E. P. and Jeffrey, N. L. S., 2010, A&A, in press.

Dennis, Brian R.; Kontar, E. P.; Gopie, A. A.; Tolbert, A. K.; Schwartz, R. A.

2010-05-01

438

Hardness Testing at Multiple Length Scales  

NSDL National Science Digital Library

University of Maryland, Department of Materials Science and Engineering (MSE) Lab Coordinator Robert Bonenberger, Ph.D., MSE Professor and Chair Robert M. Briber, Department of Mechanical Engineering (ME) Associate Professor Hugh Bruck, Jaime Cardena-Garcia, Ph.D., and MSE Associate Professor Luz Martinez-Miranda recently completed work on an NSF-funded project titled Development of Educational Materials and Acquisition of Equipment for a Nanoscale to Microscale Engineering Laboratory. The project, supported by the NSF's Course, Curriculum and Laboratory Improvement (CCLI) program, was used to develop new laboratory experiments that effectively engage undergraduate engineering students in the scientific processes and exploration of concepts in nanotechnology. Work funded under the proposal also helped integrate significant advances in nanotechnology research with the undergraduate engineering laboratory curriculum through the development of a new teaching lab. Two significant experimental systems were assembled to give students an enhanced laboratory experience: a pair of micro-tensile testers, used for determining the mechanical properties of micron-scale devices and materials; and an integrated nanoindentation/scanning probe microscope (SPM) testing system, used for measuring the hardness and elasticity of materials at the nanoscale, and for imaging samples. Bruck's junior-level ENME 382: Engineering Materials and Manufacturing Processes class was one of those that benefited from the new equipment and curriculum. This is one example of lab modules created for it as part of the overall project.

Martinez-Miranda, Luz

2009-11-27

439

Hazards of the 'hard cash': hypersensitivity pneumonitis.  

PubMed

Hypersensitivity pneumonitis (HP) is a nonimmunoglobulin E-related immune-mediated parenchymal lung disease. A 45-year-old woman who was a lifelong nonsmoker with a six-month history of frequent episodes of cough and dyspnea was admitted to hospital. She had been working as a money counter for 20 years at a central bank. Bibasilar crackles on lung auscultation, ground-glass opacities and a mosaic pattern on high-resolution computed tomography, restrictive abnormality on pulmonary function tests and mild hypoxemia were the prominent findings. Bronchoalveolar lavage fluid analysis revealed a predominance of CD4-positive T cells, and she tested positive on her natural challenge test. She was diagnosed with subacute HP based on established criteria. She was advised to discontinue counting fresh banknotes. Prednisolone was commenced, then tapered to discontinue in the ensuing six months. Clinical and radiological improvement was achieved within two months. To the authors' knowledge, the present report is the first to describe 'hard cash HP', possibly caused by chipping dust or printing dye. PMID:21038004

Kupeli, Elif; Karnak, Demet; Sak, Serpil Dizbay; Kayacan, Oya

440

Hazards of the 'hard cash': Hypersensitivity pneumonitis  

PubMed Central

Hypersensitivity pneumonitis (HP) is a nonimmunoglobulin E-related immune-mediated parenchymal lung disease. A 45-year-old woman who was a lifelong nonsmoker with a six-month history of frequent episodes of cough and dyspnea was admitted to hospital. She had been working as a money counter for 20 years at a central bank. Bibasilar crackles on lung auscultation, ground-glass opacities and a mosaic pattern on high-resolution computed tomography, restrictive abnormality on pulmonary function tests and mild hypoxemia were the prominent findings. Bronchoalveolar lavage fluid analysis revealed a predominance of CD4-positive T cells, and she tested positive on her natural challenge test. She was diagnosed with subacute HP based on established criteria. She was advised to discontinue counting fresh banknotes. Prednisolone was commenced, then tapered to discontinue in the ensuing six months. Clinical and radiological improvement was achieved within two months. To the authors’ knowledge, the present report is the first to describe ‘hard cash HP’, possibly caused by chipping dust or printing dye.

Kupeli, Elif; Karnak, Demet; Sak, Serpil Dizbay; Kayacan, Oya

2010-01-01

441

Quality Characteristics of Hard Red Spring and Winter Wheats. I. Differentiation by Reversed-Phase High-Performance Liquid Chromatography and Milling Properties  

Microsoft Academic Search

Cereal Chem. 67(5):480-485 Reversed-phase high-performance liquid chromatography was used to were also compared. HRS wheats showed higher values than HRW wheats analyze 15 commercial U.S. hard red spring (HRS) and hard red winter for total flour yield and milling score. Ratios of the total amount of (HRW) wheats. Protein content of these samples ranged from 12.0 to break flour to

S. ENDO; K. OKADA; S. NAGAO; B. L. D'APPOLONIA

442

Phase transitions of hard disks in external periodic potentials: a Monte Carlo study.  

PubMed

The nature of freezing and melting transitions for a system of hard disks in a spatially periodic external potential is studied using extensive Monte Carlo simulations. Detailed finite size scaling analysis of various thermodynamic quantities like the order parameter, its cumulants, etc., are used to map the phase diagram of the system for various values of the density and the amplitude of the external potential. We find clear indication of a reentrant liquid phase over a significant region of the parameter space. Our simulations therefore show that the system of hard disks behaves in a fashion similar to charge-stabilized colloids that are known to undergo an initial freezing, followed by a remelting transition as the amplitude of the imposed, modulating field produced by crossed laser beams is steadily increased. Detailed analysis of our data shows several features consistent with a recent dislocation unbinding theory of laser induced melting. PMID:11308911

Strepp, W; Sengupta, S; Nielaba, P

2001-03-26

443

Regularized 13 moment equations for hard sphere molecules: Linear bulk equations  

NASA Astrophysics Data System (ADS)

The regularized 13 moment equations of rarefied gas dynamics are derived for a monatomic hard sphere gas in the linear regime. The equations are based on an extended Grad-type moment system, which is systematically reduced by means of the Order of Magnitude Method [H. Struchtrup, ``Stable transport equations for rarefied gases at high orders in the Knudsen number,'' Phys. Fluids 16(11), 3921-3934 (2004)]. Chapman-Enskog expansion of the final equations yields the linear Burnett and super-Burnett equations. While the Burnett coefficients agree with literature values, this seems to be the first time that super-Burnett coefficients are computed for a hard sphere gas. As a first test of the equations the dispersion and damping of sound waves is considered.

Struchtrup, Henning; Torrilhon, Manuel

2013-05-01

444

Magnetic hard disk overcoats in the 3-5 nm thickness range  

NASA Astrophysics Data System (ADS)

Protective properties of 3-5 nm thick carbon overcoat layers deposited on magnetic hard disks by ion beam deposition (IBD) and plasma-enhanced chemical vapor deposition (PECVD) were investigated. It is found that these overcoats are superior to the sputtered carbon films at thicknesses below 5 nm. Low-stiction performance of 3-nm-thick IBD films without any detectable wear was observed during 50 000 contact start-stop cycles at 55 °C and 10% relative humidity. Surface concentration of cobalt ions is reduced by as much as an order of magnitude as compared to the media with sputtered overcoats. Polarization resistivity values for IBD and PECVD overcoats are by an order of magnitude higher. The results show that thickness of protective carbon overcoats on magnetic hard disks can be reduced to 3-5 nm without compromising media reliability requirements. This reduction is critical for the continuing growth of storage density.

Anoikin, E. V.; Yang, M. M.; Chao, J. L.; Russak, M. A.

1999-04-01

445

Starch granule size distribution of hard red winter and hard red spring wheat: Its effects on mixing and breadmaking quality.  

Technology Transfer Automated Retrieval System (TEKTRAN)

Starch was isolated from 98 hard red winter (HRW) wheat and 99 hard red spring (HRS) wheat. Granule size/volume distributions of the isolated starches were analyzed using a laser diffraction particle size analyzer. There were significant differences in the size distribution between HRW and HRS whe...

446

From hard to reach to how to reach: A systematic review of the literature on hard?to?reach families  

Microsoft Academic Search

This paper presents a review of the literature relating to hard?to?reach families which has been published over the last 12 years in the UK, USA, Canada and Australia. The purpose of the review was twofold: to gain insights to understandings of the term ‘hard?to?reach’ within these services – education, health and social – which might be aiming to access such

Maria Evangelou

2010-01-01

447

From hard to reach to how to reach: A systematic review of the literature on hard-to-reach families  

Microsoft Academic Search

This paper presents a review of the literature relating to hard-to-reach families which has been published over the last 12 years in the UK, USA, Canada and Australia. The purpose of the review was twofold: to gain insights to understandings of the term ‘hard-to-reach’ within these services – education, health and social – which might be aiming to access such

Gill Boag-Munroe; Maria Evangelou

2012-01-01

448

A hard look at hard laddering : A comparison of studies examining the hierarchical structure of means-end theory  

Microsoft Academic Search

Purpose – This paper aims to outline the fundamental assumptions regarding the laddering methodology (Reynolds and Gutman), examine how some “hard” laddering approaches meet or violate these assumptions, provide a review and comparison of a series of studies using “soft” and “hard” laddering approaches to examine the hierarchical structure of means-end theory, and assess if the discrepant conclusions from this

Joan M. Phillips; Thomas J. Reynolds

2009-01-01

449

Value, a nursing outcome.  

PubMed

This era of health care reform calls for the ability of hospitals to provide quality patient care while managing costs. Nursing practice is a key determinant of patient care quality and associated costs, or simply put, creating value. The value of nursing has been addressed by multiple qualified authors, yet there is no clear, consistent meaning of the term. Researchers and authors have developed some theoretical foundation for the concept of value, which evolved into important research questions that establish value as an important outcome that is sensitive to nursing practice. The opportunity to attend 2 sessions at the Harvard Business School on health care value has prompted the need for nursing to adapt to common thinking on health care value and establish its meaning for the nursing profession. This report summarizes the nursing literature on value, reflects on the executive education, and proposes direction for nursing leaders in education and practice. PMID:23454991

Pappas, Sharon H

450

Histological observation on dental hard tissue irradiated by ultrashort-pulsed laser  

NASA Astrophysics Data System (ADS)

In the field of dentistry, effectiveness of USPL irradiation is researched because USPL has less thermal side effect to dental hard tissue. In this paper, we observed morphological change and optical change of dental hard tissue irradiated by USPL for discussing the safety and effectiveness of USPL irradiation to dental hard tissues. Irradiated samples were crown enamel and root dentin of bovine teeth. Lasers were Ti:sapphire laser, which had pulse duration (Pd)of 130 fsec and pulse repetition rate (f) of 1kHz and wavelength (l) of 800nm, free electron laser (FEL), which had Pd of 15 ?sec and f of 10Hz and wavelength of 9.6?m, and Er:YAG laser, which had Pd of 250 ?sec and f of 10Hz and wavelength of 2.94?m. After laser irradiation, the sample surfaces and cross sections were examined with SEM and EDX. The optical change of samples was observed using FTIR. In SEM, the samples irradiated by USPL had sharp and accurate ablation with no crack and no carbonization. But, in FEL and Er:YAG laser, the samples has rough ablation with crack and carbonization. It was cleared that the P/Ca ratio of samples irradiated by USPL had same value as non-irradiated samples. There was no change in the IR absorption spectrum between samples irradiated by USPL and non-irradiated sample. But, they of samples irradiated by FEL and Er:YAG laser, however, had difference value as non-irradiated samples. These results showed that USPL might be effective to ablate dental hard tissue without thermal damage.

Uchizono, Takeyuki; Awazu, Kunio; Igarashi, Akihiro; Kato, Junji; Hirai, Yoshito

2006-05-01

451

The Role of Skin Hardness, Thickness, and Sensory Loss on Standing Foot Power in the Development of Plantar Ulcers in Patients with Diabetes Mellitus—A Preliminary Study  

Microsoft Academic Search

This article presents the results of a study on patients with diabetic neuropathy to find the relationships between the foot pressures characterized by power ratio (PR), foot sole hardness (Shore values), and foot sole soft tissue thickness. The results showed that the increase in PR values for diabetic patients in the upper sensation loss levels (S = 7.5 to 10

V. Jacob Thomas; K. Mothiram Patil; S. Radhakrishnan; V. B. Narayanamurthy; R. Parivalavan

2003-01-01

452

More about residual values.  

PubMed

The usual residual values are complemented by expectation values based solely on the experimental data and the number of model parameters. These theoretical R values serve as benchmark values when all of the basic assumptions for a least-squares refinement, i.e. no systematic errors and a fully adequate model capable of describing the data, are fulfilled. The prediction of R values as presented here is applicable to any field where model parameters are fitted to data with known precision. For crystallographic applications, F(2)-based residual benchmark values are given. They depend on the first and second moments of variance, intensity and significance distributions, ??(2)?, ?Io(2)?, ?Io(2)/?(2)?. Possible applications of the theoretical R values are, for example, as a data-quality measure or the detection of systematic deviations between experimental data and model predicted data, although the theoretical R values cannot identify the origin of these systematic deviations. The change in R values due to application of a weighting scheme is quantified with the theoretical R values. PMID:24132216

Henn, Julian; Schönleber, Andreas

2013-10-02

453

Size Effects in Nano-phase Hard Magnetic Materials  

NASA Astrophysics Data System (ADS)

This dissertation work was focused on the behavior of the hard magnetic materials in the nano-size and under confinement in special geometries. Three distinct systems have been examined carefully to see the effects of nano dimensions on the intrinsic and hard magnetic properties of these materials, namely Alnico thin films, Sm-Co and FePt nanoparticles. In our research work to study the spinodal decomposition of Alnico thin films prepared by sputtering on Si substrates, it has been discovered that Si diffuses into the films and gives rise to a new magnetically hard phase with TC=305°C. The phase formation occurs following the annealing at 900°C, which gave a room temperature coercivity 6.5 kOe. The maximum coercivity observed is approximately ten times larger than the bulk Alnico V value. The aim of the second project was to synthesize Sm-Co nanoparticles with high HC in the as-made state. During RT synthesis, 3.5 nm superparamagnetic SmCo5 nanoparticles have been successfully produced via the Cluster Beam Deposition (CBD) technique. Dispersion of the SmCo5 nanoparticles in a carbon matrix resulted in increase in both the coercivity and the blocking temperature. Room temperature coercivities as high as 12 kOe have been obtained for the first time in mono-layers of SmCo5 nanoparticles dispersed in C matrix. ?M plots showed that the interactions in the sample with closed packed particles are of exchange type, which lead to a decrease the overall effective anisotropy and coercivity according to the random-anisotropy model. For the third project of this dissertation, single crystal FCT FePt nanocubes have been successfully produced by a CBD technique without the need of post annealing. The nanocubes have a uniform size distribution with an average size of 6.5 nm. At 1 Torr, the particles have the FCT structure with an order parameter of 0.5 and a RT coercivity of 2 kOe. Further annealing increased the particle size to 20 nm and the RT coercivity to 10.2 kOe with perfect chemical ordering. In addition to these nanocubes, micron size rods with the FCT structure have been observed near the cluster gun. SEM analysis showed that these rods consist of nanoparticles with 20 nm average size. The new phase formation in the Alnico systems is important in view of the recent "rare earth problem" and may lead to alternative to rare earth materials for the development of high performance magnets. FePt and SmCo5 nanoparticles have a potential for use in the development of future high-density magnetic recording media because of their high coercivity, good shape and very narrow size distribution.

Akdogan, Ozan

454

Parents welcome "hard-hitting" campaign.  

PubMed

The FPA (Family Planning Association)'s recent pilot campaign to encourage parents to talk to their children about sex has generated an excellent response rate. Funded by the Department of Health as part of "The health of the nation" efforts to reduce unplanned teenage pregnancies, the campaign centered on two radio advertisements. Aired during March in Greater London and North West England, the advertisements featured a free phone number from which people could obtain free copies of the booklet "Answering your child's questions," part of the FPA's "Growing Up" series. Nearly 7500 copies of the booklet were distributed in response to over 5000 requests--2500 rang in the first week alone. Most requests were from parents (69% mothers, 31% fathers) with one to three children aged between 7 and 13. Over 1000 requests were from parents with children under 7. Hundreds of schools, youth clubs, health professionals and voluntary organizations requested multiple booklets for use in their work. Research carried out to gauge public reaction showed overwhelming support for the campaign's message, demonstrating the immense need by parents for information in this area. "Answering your child's questions" was praised for being "open, direct and easy to follow." One parent said, "The booklet arms parents with the right way of putting information across." Parents described the advertisements as "hard-hitting" and "attention-grabbing." One listener commented: "They really stopped me in my tracks." FPA director Doreen Massey said: "The favorable reaction to the campaign is extremely encouraging. We are looking at ways to relay this pilot effort into a full-scale UK-wide campaign next year." PMID:12287880

1994-01-01

455

High efficiency, radiation-hard solar cells  

SciTech Connect

The direct gap of the In{sub 1-x}Ga{sub x}N alloy system extends continuously from InN (0.7 eV, in the near IR) to GaN (3.4 eV, in the mid-ultraviolet). This opens the intriguing possibility of using this single ternary alloy system in single or multi-junction (MJ) solar cells of the type used for space-based surveillance satellites. To evaluate the suitability of In{sub 1-x}Ga{sub x}N as a material for space applications, high quality thin films were grown with molecular beam epitaxy and extensive damage testing with electron, proton, and alpha particle radiation was performed. Using the room temperature photoluminescence intensity as a indirect measure of minority carrier lifetime, it is shown that In{sub 1-x}Ga{sub x}N retains its optoelectronic properties at radiation damage doses at least 2 orders of magnitude higher than the damage thresholds of the materials (GaAs and GaInP) currently used in high efficiency MJ cells. This indicates that the In{sub 1-x}Ga{sub x}N is well-suited for the future development of ultra radiation-hard optoelectronics. Critical issues affecting development of solar cells using this material system were addressed. The presence of an electron-rich surface layer in InN and In{sub 1-x}Ga{sub x}N (0 < x < 0.63) was investigated; it was shown that this is a less significant effect at large x. Evidence of p-type activity below the surface in Mg-doped InN was obtained; this is a significant step toward achieving photovoltaic action and, ultimately, a solar cell using this material.

Ager III, J.W.; Walukiewicz, W.

2004-10-22

456

Nucleation-Mode Localization in Hard-Soft Nanocomposites  

NASA Astrophysics Data System (ADS)

Aligned hard-soft nanocomposites continue to be an active research area in permanent magnetism, challenged by demanding processing requirements but also encouraged by experimental proofs of principle. The approach was initially outlined by Kneller and Hawig (1991), who advocated hard-soft multilayers. Skomski and Coey (1993) considered three-dimensional nanostructures, such as soft spheres in a hard matrix, and predicted an upper energy-product limit of about 1000 kJ/m^3. It is well-established that the dimensions of the soft regions cannot be larger than twice the domain-wall width of the hard phase, but otherwise it was believed that geometry has a rather secondary effect. However, our recent research reveals substantial differences. Soft-in-hard geometries are better than hard-in-soft geometries and embedded soft spheres are better than multilayers. This is in close analogy to the dimensionality-dependent quantum-mechanical delocalization of electrons in an inhomogeneous potential and to the behavior of impurity states in the band gaps of solids. Transparent analytical nucleation-field solutions are found for some geometries and in the limit of very small soft inclusion as a function of the hard-phase coercivity and hysteresis-loop shape.

Skomski, Ralph; Balasubramanian, Balamurugan; Das, Bhaskar; Sellmyer, D. J.

2013-03-01

457

Guided waves for monitoring heat treatment duration and material hardness  

NASA Astrophysics Data System (ADS)

Elastic properties of materials can be easily determined from the ultrasonic wave velocity measurement. However, material hardness cannot be obtained from the ultrasonic wave speed. Heat treatment and aging affect the microstructure of materials changing their hardness and strength. In this study it is investigated how the attenuation of ultrasonic guided waves is affected by the duration of heat treatment and varying material hardness. To this aim six identical Aluminum 2024 alloy plate specimens were subjected to different durations of heat treatment at 150°C and were inspected nondestructively propagating Lamb waves through the specimens. Attenuation of the Lamb wave was found to be inversely related to the hardness. Rockwell Hardness test was performed to corroborate the ultrasonic observations. In comparison to Rockwell hardness test the ultrasonic inspection was found to be more sensitive to the heat treatment duration. From these results it is concluded that guided wave inspection method is a reliable and probably more desirable alternative for characterizing the hardness of heat treated materials.

Korde, Nilesh; Kundu, Tribikram

2012-03-01

458

Chromium nitride-silver self-lubricating nanoporous hard coatings  

NASA Astrophysics Data System (ADS)

The focus of this thesis research is to explore a new approach to adaptive solid lubrication using nanoporous hard coatings. To investigate this approach, I deposited prototype coatings for study consisting of a hard chromium nitride (CrN) matrix co-deposited with a lubricious silver (Ag) phase by reactive magnetron co-sputtering. The idea is to exploit the relative immiscibility of the two phases to create nanocomposite structures with intrinsic lubricant transport properties enabled by the presence of the nanopores. Specifically, I develop the scientific understanding of the critical growth parameters that govern nanocomposite structural evolution which in turn control mechanical properties, solid lubricant diffusion, and tribological response. Mechanical properties were analyzed by both micro and nanoindentation measurements for the composites as a function of Ag aggregate morphology. For Ts ? 500°C, hardness as measured by nanoindentation into the surface is relatively uniform giving values of 14.6, 13.6, and 14.3 GPa for Ts = 300, 400, and 500°C respectively. For Ts > 500°C, the cross-sectional microhardness increases with T s from 16.5 to 19.7 to 24.3 GPa for Ts = 500, 600, and 700°C, respectively, which is attributed to a decrease in the effective Ag concentration associated with temperature activated segregation. The average hardness for pure CrN samples is 23.8 and 27.5 GPa as measured by surface nanoindentation and cross-sectional microindentation, respectively. Lubricant transport behavior was characterized by a series of vacuum annealing experiments. Vacuum annealing experiments at Ta = 425, 525, and 625°C show that Ag diffuses to the coating surface to form lubricious surface aggregates and that the rate for Ag lubricant transport increases with increasing DeltaT (Ta - Ts) for Ta > Ts, as determined by quantitative electron microscopy surface analyses. However, the Ag remains in the CrN matrix for Ta < Ts, which is attributed to the Ag aggregate size distribution within the coating which affects the chemical potential. Friction and wear behavior were measured in ambient air at test temperatures, Tt = 20°C to 700°C to study the self-lubricating properties and tribological mechanisms of the coatings as a function of structure and lubricant transport properties. Ball-on-disk tribological tests against 100Cr6 steel at Tt = 20°C indicate that the Ag grains for Ts = 500°C are too small to facilitate an effective lubricious surface layer, resulting in a friction coefficient micro = 0.58 and a composite coating wear rate of 3.8x10-6 mm3/Nm that are nearly identical to those measured for pure CrN with micro = 0.64 and 3.6x10-6 mm3/Nm. The Ts = 600°C coating exhibits a 15% higher Ag concentration on the surface of the wear track than outside the wear track which acts as a lubricious layer that reduces micro to 0.47 and yields a 16x and 2.4x lower wear rate for coating and counterface, respectively. Replacing the steel counterface with an alumina ball results in the lowest micro = 0.50 for Ts = 500°C, attributed to the presence of Ag and the relatively low hardness of 16.5 GPa for this particular coating. High temperature tribological response during ball-on-disk sliding in ambient air against alumina was found to depend strongly on both Ts and the testing temperature Tt = 450, 550, and 650°C. At Tt < Ts, the friction coefficient micro = 0.31--0.34, which is 25--35% below pure CrN with micro = 0.45. This moderate lubrication improvement is attributed to the presence of lubricious Ag within the CrN matrix. In contrast, Tt > Ts results in Ag lubricant transport to the coating surface and the formation of an effective self-lubricating layer, reducing the friction up to 65% to micro = 0.16--0.24. However, raising Tt well above Ts causes relatively rapid lubricant transport to the surface, followed by Ag depletion which results in a short low micro regime followed by a rapid rise in micro and often mechanical collapse of the matrix. The measured wear rate also strongly depends on the Ag sol

Mulligan Christopher P

459

The Value Chain  

NSDL National Science Digital Library

From Industry Week, The Value Chain is an online publication providing up-to-date information, articles, and resources on value chain management (VCM), a theory of management that considers every step of manufacturing a product, from raw materials "right down to disposing of the packaging after use." Along with feature articles and columns about value chain management, the site also contains a FAQ, which offers excellent basic advice about VCM, a New Roundup Weblog of breaking VCM news, and short research pieces.

460

Missing Value Estimation  

Microsoft Academic Search

KNNimpute is a fast, robust, and accurate method of estimating missing values for microarray data. Both KNNimpute and SVDimpute\\u000a methods far surpass the currently accepted solutions (filling missing values with zeros or row average) by taking advantage\\u000a of the structure of microarray data to estimate missing expression values.\\u000a \\u000a We recommend KNNimpute over SVDimpute method for several reasons. First, the KNNimpute

Olga Troyanskaya; David Botstein; Russ Altman

461

Hard X-ray imaging with a slat collimated telescope.  

NASA Astrophysics Data System (ADS)

Imaging experiments with a slat collimated hard X-ray telescope are described in this paper demonstrating the feasibility of the direct demodulation imaging method used in hard X-ray scanning modulation experiments. On 25 September 1993 an X-ray raster scan observation of Cyg X-1 was performed in a balloon flight with the hard X-ray telescope HAPI-4. An experiment to image radioactive X-ray sources was previously performed in the laboratory. In both experiments the expected X-ray images were obtained, confirming the imaging capability of this method.

Lu, Zhuguo; Wang, Jianzhong; Li, Yanguo; Shen, Peiruo; Zhu, Zian; Yang, Jawei; Yang, Huzhi; Lin, Baojun; Zhang, Xiyuan; Li, Chenug; Bin, Zhangmo; Wu, Mei; Li, Tipei; Staubert, R.; Kotov, Yu. D.; Suslov, A. Yu.

1995-08-01

462

Hard X-ray imaging with a slat collimated telescope  

NASA Astrophysics Data System (ADS)

Imaging experiments with a slat collimated hard X-ray telescope are described in this paper demonstrating the feasibility of the direct demodulation imaging method used in hard X-ray scanning modulation experiments. On 25 September 1993 an X-ray raster scan observation of Cyg X-1 was performed in a balloon flight with the hard X-ray telescope HAPI-4. An experiment to image radioactive X-ray sources was performed in the laboratory before. In both experiments the expected X-ray images were obtained, confirming the imaging capability of this method.

Zhuguo, Lu; Jianzhong, Wang; Yanguo, Li; Peiruo, Shen; Zian, Zhu; Jawei, Yang; Huzhi, Yang; Baojun, Lin; Xiyuan, Zhang; Bin, Liu; Chengmo, Zhang; Mei, Wu; Tipei, Li; Staubert, R.; Kotov, Yu. D.; Suslov, A. Yu.

1995-02-01

463

A scaling rule of indentation hardness of semiconductors  

Microsoft Academic Search

We report a scaling rule of the indentation hardness of semiconductor crystals from room temperature to their melting. The Vickers hardness of fifteen semiconductors, Si, Ge, SiC, AlN, GaN, GaP, GaAs, GaSb, InP, InAs, InSb, ZnO, ZnSe, ZnTe and CdTe, has been investigated from room temperature to their melting points. The temperature dependences of the hardness H v of eleven

Ichiro Yonenaga; Takayoshi Suzuki

2003-01-01

464

Non-conventional tungsten-base hard metal  

SciTech Connect

A novel hard-metal composition comprising borides and carbides of tungsten, nickel, and iron is made by reaction hot pressing mixtures of elemental tungsten, nickel, and iron powders with small quantities of boron carbide. The hardness of these compositions is in the range of the hardest conventional tungsten carbide-cobalt compositions. It was subsequently determined that molybdenum can be substituted for all the tungsten in the composition, and elemental boron can be substituted for the boron carbide with a minimum reduction in hardness. The new composition can be used in high-pressure anvils; it sustains higher pressures than commercial carbides without plastic deformation.

Sheinberg, H.

1981-01-01

465

Connection between micro and macro hardness pearlitic-ferritic steel  

NASA Astrophysics Data System (ADS)

Many physical and mechanical properties of materials are closely related to their microstructure, technologies to control the microstructure of materials have been well developed to obtain suitable properties. We measured the volume fraction of perlite and ferrite, micro Vickers hardness in pearlite and ferrite and macro hardness using different sample with different carbon content. The volume fraction of pearlite increases by increasing carbon content. By increasing carbon content, micro and macro hardness increase. We can conclude that for those conditional the mixing rule can't be use.

Duka, Edlira; Oettel, Heinrich; Dilo, Teuta

2012-09-01

466

The plain, hard truth about pathogen monitoring  

Microsoft Academic Search

Pathogen monitoring has concerned microbiologists for nearly a century. Over several years, numerous factors have inflated the value of pathogen monitoring for public health protection and led to such developments as the promulgation of the Information Collection Rule (ICR). Eighteen months of ICR data have only served to underscore the monitoring method's limitations. Methods 1622 and 1623 represent significant improvements

Martin J. Allen; Jennifer L. Clancy; Eugene W. Rice

2000-01-01

467

Lessons of Diversity Learned the Hard Way  

ERIC Educational Resources Information Center

Through experiences training teachers across the country, the author gains insight into the necessity to accommodate diverse Native American learners. Sensitivity to Native American learning styles and values enables the author to better meet individual needs and learn valuable lessons in diversity. The author tells the story of her experiences…

Morrison, Kathy

2009-01-01

468

Study of the compaction mechanisms of lactose-based direct compression excipients using indentation hardness and Heckel plots.  

PubMed

Indentation hardness of tablet surfaces has been used to determine the consolidation mechanisms of the lactose-based excipients Fast Flo Lactose, Ludipress, Cellactose and Tablettose. The Leuenberger equation has been modified to obtain values of compressibility and compactability by using a value of compactability obtained from a tablet at maximum applied force and by substituting deformation resistance by relative deformation resistance. Also, parameters obtained from plots of the Heckel tablet-indie and ejected-tablet methods were calculated in order to establish the comparative consolidation mechanisms in the lactose-based excipients under study. The possibility of using the absolute value of the difference between upper and lower surface hardnesses of the tablets made on an eccentric press is suggested as an alternative method to determine the comparative consolidation mechanisms of different substances. PMID:8027923

Monedero Perales, M D; Muñoz-Ruiz, A; Velasco Antequera, M V; Jiménez-Castellanos Ballesteros, M R

1994-03-01

469

Estimation of calcified tissues hardness via calcium and magnesium ionic to atomic line intensity ratio in laser induced breakdown spectra  

NASA Astrophysics Data System (ADS)

Calcified tissues representing three different matrices, namely enamel of human teeth, shells and eggshell, have been studied via Laser Induced Breakdown Spectroscopy (LIBS) technique. The experimental CaII/CaI and MgII/MgI ratios have been measured, in view of the expected correlation between the extent of ionization caused by the laser induced shock wave (SW) and the hardness of the target. The ratio CaII/CaI between the ionic calcium line at 373.69 nm and the neutral line at 428.9 nm is obtained for enamel, shells and eggshell spectra, as well as the ratio MgII/MgI between the ionic magnesium line at 280.26 nm and the neutral line at 285.22 nm. The results show that such spectral lines intensities ratio differs for different matrices and is indeed related to the target materials hardness. It is also found that the MgII/MgI ratio is preferable as an indicator of hardness since these lines are less affected by self absorption. The SW front speed has been measured in the three cases and the obtained values confirm the proportionality to the target hardness. The results here obtained suggest the feasibility of the quantitative estimation of hardness for any other calcified tissues.

Abdel-Salam, Z. A.; Galmed, A. H.; Tognoni, E.; Harith, M. A.

2007-12-01

470

Effect of water hardness on surface tension and dilational visco-elasticity of sodium dodecyl sulphate solutions.  

PubMed

The complementary drop and bubble profile analysis and maximum bubble pressure tensiometry are used to measure the dynamic surface tension of aqueous SDS solutions in the presence of hardness salts (CaCl(2) and MgCl(2) in the ratio of 2:1 at concentrations of 6 and 40FH). The presence of hardness salts results in an essential increase of the SDS adsorption activity, which indicates the formation of Ca(DS)(2) and Mg(DS)(2) in the SDS solutions. The surface tension isotherms of SDS in presence of Ca(DS)(2) and Mg(DS)(2) are described using the generalised Frumkin model. The presence of hardness salts accelerates the ageing of SDS solutions as compared with the addition of 0.01 M NaCl due to a faster hydrolysis and hence formation of dodecanol. These results are used to estimate the possible concentration of dodecanol in the studied SDS solutions. The buoyant bubble profile method with harmonic surface oscillations is used to measure the dilational rheology of SDS solutions in presence of hardness salts in the frequency range between 0.005 Hz and 0.2 Hz. The visco-elasticity modulus in the presence of hardness salts is higher as compared with its values in the presence of 0.01 M NaCl additions. The ageing of SDS solutions leads to an essential increase of the visco-elastic modulus. PMID:22484167

Fainerman, V B; Lylyk, S V; Aksenenko, E V; Kovalchuk, N M; Kovalchuk, V I; Petkov, J T; Miller, R

2012-03-20

471

Currency Value Game  

NSDL National Science Digital Library

With this interactive game students practice identifying names and values of US currency. It provides a picture of one of the U.S. coins or the dollar bill, and a question prompt, both printed and voiced, that asks the value. Sound clips reward correct responses or encourage another try. The game comprises a five question set.

Petro, Brian

2004-09-28

472

Sustaining NCTE Values  

ERIC Educational Resources Information Center

NCTE's core values, posted on the website (http://www.ncte.org), are writing, literature, diversity, integrated language arts, knowledgeable and caring teachers, advocacy, and public education ("NCTE Core Values"). In this article, the author focuses only on writing, diversity, and advocacy, considering just a few ways in which the organization…

Logan, Shirley Wilson

2011-01-01

473

Ecology and Human Values.  

ERIC Educational Resources Information Center

|"Ecology and Human Values" is an interdisciplinary course designed for senior year high school students in social studies and/or science. Its main thrust is the investigation of human values as they relate to the environment, although rooted in the natural sciences as a means of understanding the complexities inherent in the environment. Use is…

1970

474

Judgments of Relative Values  

Microsoft Academic Search

Three scales of statements were devised to test the capacity for judging relative values, namely, (1) Reasons for going to high school. (2) Reasons for saving money. (3) Reasons for reading good literature. School grades 6, 7 and 8 were tested with these scales. In grades 6 and 7 the capacity for judging relative values is represented by a coefficient

J. C. Chapman

1920-01-01

475

Dance: Verities, Values, Visions.  

ERIC Educational Resources Information Center

|The Binational Dance Conference was organized into three focal themes--verities, values, and visions in dance--to emphasize the known and accepted worth and value of dance, and to stimulate through knowledge and idea exchange, imaginative directions for dance in the future of both the United States and Canada. This thematic structure is also the…

Boorman, Joyce, Ed.; Harris, Dorothy, Ed.

476

Looking for Core Values  

ERIC Educational Resources Information Center

|People who view themselves as leaders, not just managers or teachers, are innovators who focus on clarifying core values and aligning all aspects of the organization with these values to grow their vision. A vision for an organization can't be just one person's idea. Visions grow by involving people in activities that help them name and create…

Carter, Margie

2010-01-01