Crystallographic study of grain refinement in aluminum alloys using the edge-to-edge matching model

The edge-to-edge matching model for describing the interfacial crystallographic characteristics between two phases that are related by reproducible orientation relationships has been applied to the typical grain refiners in aluminum alloys. Excellent atomic matching between Al3Ti nucleating substrates, known to be effective nucleation sites for primary Al, and the Al matrix in both close packed directions and close packed planes containing these directions have been identified. The crystallographic features of the grain refiner and the Al matrix are very consistent with the edge-to-edge matching model. For three other typical grain refiners for Al alloys, TiC (when a = 0.4328 nm), TiB2 and AIB(2), the matching only occurs between the close packed directions in both phases and between the second close packed plane of the Al matrix and the second close packed plane of the refiners. According to the model, it is predicted that Al3Ti is a more powerful nucleating substrate for Al alloy than TiC, TiB2 and AlB2. This agrees with the previous experimental results. The present work shows that the edge-to-edge matching model has the potential to be a powerful tool in discovering new and more powerful grain refiners for Al alloys. (C) 2004 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Comments on edge-to-edge matching and the equivalence of the invariant line, Delta g and Moire fringe approaches to the crystallographic features of precipitates

Three apparently distinct and different approaches have been proposed to account for the crystallographic features of diffusion-controlled precipitation. These three models are based on (a) an invariant line in the habit plane, (b) the parallelism of a pair of Deltags that are perpendicular to the habit plane and (c) the parallelism of a pair of Moire fringes that are in turn parallel to the habit plane. The purpose of the present paper is to show that these approaches are in fact absolutely equivalent and that when certain conditions are satisfied they are essentially the same as the recent edge-to-edge matching model put forward by the authors. (C) 2004 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Edge-to-edge matching and its applications - Part I. Application to the simple HCP/BCC system

The edge-to-edge matching crystallographic model has been used to predict all the orientation relationships (OR) between crystals that have simple hexagonal close packed (HCP) and body-centered cubic (BCC) structures. Using the critical values for the interatomic spacing misfit along the matching directions and the cl-value mismatch between matching planes, the model predicted all the four common ORs, namely the Burgers OR, the Potter OR, the Pitsch-Schrader OR and the Rong Dunlop OR, together with the corresponding habit planes. Taking the c(H)/a(H) and a(H)/a(B) ratios as variables, where H and B denote the HCP and BCC structures respectively, the model also predicted the relationship between these variables and the four ORs. These predictions are perfectly consistent with the published experimental results. As was the case in the FCC/BCC system, the edge-to-edge matching model has been shown to be a powerful tool for predicting the crystallographic features of diffusion-controlled phase transformations. (C) 2004 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Edge-to-edge matching and its applications - Part II. Application to Mg-Al, Mg-Y and Mg-Mn alloys

A model for the crystallography and morphology of diffusion-controlled phase transformations - edge-to-edge matching - has been used to predict the orientation relationships (OR) and habit planes of precipitates Mg17Al12 in Mg-Al alloy, Mg24Y5 in Mg-Y alloy and alpha-Mn in Mg-Mn alloy. Based on the crystal structures and lattice parameters only, the model predicts that the possible ORs between Mg17Al12 and Mg matrix are the near Burgers OR, the Potter OR, the Gjonnes-Ostmoe OR and the Crawley OR. In the Mg-Y alloy, the OR between Mg24Y5 precipitates and the Mg matrix is predicted to be the Burgers OR only. The model also predicts that there are no reproducible ORs between alpha-Mn and Mg in the Mg-Mn alloy. Combining the edge-to-edge matching model and W. Zhang's Deltag approach, the habit plane and side facets of the precipitate for each OR can be determined. All the predicted ORs and the corresponding habit planes in Mg-Al and Mg-Y alloys agree very well with the experimental results. (C) 2004 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Application of edge-to-edge matching model to understand the in-plane texture of TiSi2 (C49) thin films on (001)(Si) surface

The edge-to-edge matching model, which was originally developed for predicting crystallographic features in diffusional phase transformations in solids, has been used to understand the formation of in-plane textures in TiSi2 (C49) thin films on Si single crystal (001)si surface. The model predicts all the four previously reported orientation relationships between C49 and Si substrate based on the actual atom matching across the interface and the basic crystallographic data only. The model has strong potential to be used to develop new thin film materials. (c) 2006 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Understanding the crystallography of the eutectoid microstructure in a Zn-Al alloy using the edge-to-edge matching model

The orientation relationship (OR) between the beta(Zn) phase and the alpha(Al) phase and the corresponding habit planes in a Zn-Al eutectoid alloy were accurately determined using convergent beam Kikuchi line diffraction patterns. In addition to the previously reported OR. [11 (2) over bar0](beta)parallel to[110](alpha), (0002)(beta)parallel to ((1) over bar 11)alpha, two new ORs were observed. They are: [11 (2) over bar0](beta)parallel to [110], ((1) over bar 101)(beta) 0.82 degrees from (002)(alpha) and [(1) over bar 100](beta)parallel to[112](alpha), (0002)(beta) 4.5 degrees from (111)(alpha). These ORs can be explained and understood using the recently developed edge-to-edge matching model. (c) 2006 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Edge-to-edge matching - The fundamentals

The basis of the present authors' edge-to-edge matching model for understanding the crystallography of partially coherent precipitates is the minimization of the energy of the interface between the two phases. For relatively simple crystal structures, this energy minimization occurs when close-packed, or relatively close-packed, rows of atoms match across the interface. Hence, the fundamental principle behind edge-to-edge matching is that the directions in each phase that correspond to the edges of the planes that meet in the interface should be close-packed, or relatively close-packed, rows of atoms. A few of the recently reported examples of what is termed edge-to-edge matching appear to ignore this fundamental principle. By comparing theoretical predictions with available experimental data, this article will explore the validity of this critical atom-row coincidence condition, in situations where the two phases have simple crystal Structures and in those where the precipitate has a more complex structure.

Stability and continuity of women's core beliefs and psychopathological symptoms from pregnancy to one year postpartum

Unhealthy core beliefs are theorized to be stable constructs throughout the life-span, but no research to date, outside of the context of clinical intervention, has addressed this claim over a period of greater than 6 weeks. This study explores the stability and continuity of core beliefs and psychopathological symptoms in a group of women over a major life event and for 1 year subsequently. Eighty-seven women completed measures assessing their core beliefs and psychopathological symptoms during pregnancy and at 6 and 12 months after giving birth. General maternal psychopathological symptoms significantly decreased across the group between pregnancy and 6 months postpartum, and between pregnancy and 1 year, but showed evidence of stability in the ranks of individuals across time. The majority of core beliefs remained both stable and continuous throughout this period of major transition. These findings generally support the theoretical contention that core beliefs are relatively stable and continuous self-constructs. Science+Business Media, LLC.

Megtakarítások és külső finanszírozás az amerikai gazdaságban. A hitelpiaci válság háttere (1997-2007) (Savings and external financing in the American economy. The background to the credit-market crisis (1997–2007))

A tanulmány nem az aktuális hitelpiaci válság enyhítésének kérdésével foglalkozik, hanem az amerikai gazdaság elmúlt négy évtizedének általános és az utolsó tíz évének konkrét beruházási-megtakarítási és növekedési tendenciáit igyekszik feltárni. Azt vizsgálja, hogy milyen mélyebb, belföldi eredetű szerkezeti okai vannak a nemzetközivé dagadt jelzáloghitel-válságnak. A cikk a nyitott gazdaság külső finanszírozással összefüggő mérlegazonosságainak alapján arra a következtetésre jut, hogy az ingatlanpiaci visszaesés és a kibocsátás zsugorodása az Egyesült Államok gazdaságában már több mint másfél évtizede kialakult kedvezőtlen, de még tovább romló belföldi megtakarítási folyamatok következménye. A jelzálogpiac krízise és a lakásépítés drámai visszaesése a túlfogyasztásra és túlhitelezésre ösztönző pénzügyi környezet eredménye. A lakáspiaci és a hitelezési ciklusok pénzügyi innovációkkal történő megnyújtása inkább növelte, mint csökkentette a kibocsátásingadozás érzékenységét. A legfőbb hitelezők Kína, Japán, Németország inkább dolláralapú amerikai vállalati felvásárlásokkal ellensúlyozták a dollárgyengülésből elszenvedett veszteségeiket. 1997-2007 között az Amerikából külföldön befektetett dolláraktívák - javarészt a valuta leértékelődése nyomán - jelentős hozamemelkedést élveztek, és számottevően tompították a belföldön képződött jövedelmek csökkenését. A dollárleértékelődés az eszköz- (és nemcsak az áruexport) oldalon is előnyöket hozott számos nagyvállalatnak. / === / Rather than dealing with the immediate policy steps to dampen the crisis, this paper attempts to reveal the worsening savings/consumption pattern of the US economy over the last ten years. Based on the closed logic of open-economy GDP-accounting, it argues that the current crisis is deeply rooted in shrinking public and private savings trends discernible as early as 1997. The current mortgage-market crisis and deep fall in new residential housing are products of a distorted financial environment that encourages over-borrowing and over-consumption. Expansion of the credit cycle through successive financial innovations has increased, not decreased output volatility. But the main foreign lenders to the US—Japan, China and Germany—have managed to offset their losses on US securities by buying into US companies. Large US firms have also benefited from rapid dollar depreciation as USD-denominated yields on their foreign assets experienced strong run-ups. The weak dollar has also helped American firms with large assets on foreign markets. So there were strong benefits for the US, not just on the goods-export side, but on the asset side, an aspect rarely emphasized.

Az exportpiac-orientáció előzményei és annak exportteljesítményre gyakorolt hatása a magyar felsőoktatási intézményekben (Antecedents to the export market orientation of Hungarian higher education institutions, and their export performance consequences)

A felsőoktatás nemzetközi versenyképességének vizsgálata azt mutatja, hogy egyre szélesebb körben alkalmazzák a sikeres egyetemek azokat a megközelítéseket, amelyeket az elmúlt fél évszázadban a menedzsmentirodalom az üzleti szférában meghonosított. A szerzők a felsőoktatási ágazatra terjesztik ki az exportpiac- orientáció elméletét, és azt vizsgálják, hogy milyen előzmények vezetnek annak kialakulásához. Elemzik továbbá, hogy az exportpiac-orientáció milyen hatással van a felsőoktatási intézmények exportteljesítményére. A tanulmány továbbá kitér az exportpiac-orientáció és az exportteljesítmény kapcsolatát befolyásoló környezeti tényezők hatásának vizsgálatára is. A szerzők az említett összefüggéseket két almintán vizsgálják (a nemzetköziesedésben és a tudományos kutatásban vezető egyetemek vs. az előbbi dimenziókban gyengébben teljesítő felsőoktatási intézmények). Az eredmények alapján megállapítják, hogy az exporttapasztalat mindkét egyetemi csoportnál az exportteljesítmény szignifikáns előrejelzője, míg az exportkoordináció csupán a nemzetköziesedésben gyengébben teljesítő egyetemek csoportjánál magyarázza az exportpiac-orientáció változását. Megfigyelhető továbbá, hogy az exportpiac-orientáció exportteljesítményre gyakorolt hatása erősebb a nemzetköziesedésben vezető magyar egyetemeknél, míg a nemzetközi piacokon tapasztalható verseny intenzitása fokozza a nemzetközi irányultság kialakulását ugyanezen csoportnál. ______ The authors extend the theory of export market orientation to the higher education sector, and explore the association between export coordination, export experience, export market orientation, export performance and the competitive environment in the context of Hungarian higher education sector. The aforementioned relations are analyzed on two subsamples (universities with a top performance vs. universities with a lower performance in regard of internationalization and scientific research). Based on the results, the authors conclude that export experience is a significant predictor of export performance in both groups of institutions, while export coordination can only explain changes in export market orientation for the group comprising the universities that lag behind in terms of internationalization. They observe, moreover, that export market orientation becomes stronger as competitive forces in the environment intensify.

Comparison of two mentoring programs for at -risk Black adolescents: A traditional one -to -one mentoring program and a school -to -work transitional program

The purposes of this study were: (a) to compare the impact of One-to-One (OTO) mentoring interventions administered in the high school setting, and the workplace of the students who participated in the School-to-Work (STW) transitional program, and (b) to identify how the participants perceived their experience in the OTO mentoring program and the STW transitional program. A qualitative approach was used to identify how participants perceived their mentoring experiences with the STW and OTO mentoring programs by utilizing focus groups and content analysis. A quantitative approach was used to compare the statistical differences of outcomes between the STW and OTO mentoring programs, by utilizing descriptive statistics, independent samples t-tests, chi-square analyses, and logistic regression. The sample was limited to participants in the STW and OTO mentoring programs resulting in 21 participants for the qualitative approach and 114 participants for the quantitative approach. ^ Results from the qualitative approach indicated that focus group participants in the STW program were satisfied with the program and the relationship with their mentors. They also suggested that the STW program be lengthened to include the entire academic year. Participants from the OTO focus group were dissatisfied with their program due to inadequate mentor involvement. Results from the quantitative approach showed that the increase in school attendance for the STW program's at-risk Black male youth was statistically significant compared to the OTO program participants; the STW program participants displayed a better outlook for attending college that was statistically significant compared to those in the OTO program; and the OTO program participants displayed a better outlook for permanent employment compared to those in the STW program. ^ Therefore, this study finds that mentoring can contribute to reducing school absences and high school completion in order for at-risk Black adolescents to attend college. It is recommended that the OTO program be restructured to eliminate the disparity that exists regarding the administration of the STW program and the OTO program. ^

Authentication of concast communication

In this paper we tackle the problem of finding an efficient signature verification scheme when the number of signatures is signi.- cantly large and the verifier is relatively weak. In particular, we tackle the problem of message authentication in many-to-one communication networks known as concast communication. The paper presents three signature screening algorithms for a variant of ElGamal-type digital signatures. The cost for these schemes is n applications of hash functions, 2n modular multiplications, and n modular additions plus the verification of one digital signature, where n is the number of signatures. The paper also presents a solution to the open problem of finding a fast screening signature for non-RSA digital signature schemes.

Detection of sinkhole attack in wireless sensor networks

Generally wireless sensor networks rely of many-to-one communication approach for data gathering. This approach is extremely susceptible to sinkhole attack, where an intruder attracts surrounding nodes with unfaithful routing information, and subsequently presents selective forwarding or change the data that carry through it. A sinkhole attack causes an important threat to sensor networks and it should be considered that the sensor nodes are mostly spread out in open areas and of weak computation and battery power. In order to detect the intruder in a sinkhole attack this paper suggests an algorithm which firstly finds a group of suspected nodes by analyzing the consistency of data. Then, the intruder is recognized efficiently in the group by checking the network flow information. The proposed algorithm's performance has been evaluated by using numerical analysis and simulations. Therefore, accuracy and efficiency of algorithm would be verified.