bluuebunny/crossref_metadata_2025 huggingface dataset:
Highly wear resistant chemisorbed polar ultra-high-molecular-weight polyethylene thin film on Si surface for micro-system applications
Authors: Satyanarayana Nalam , Sinha Sujeet K. , Lim Seh-Chun
Published: October 2009

We report deposition and tribological studies of a chemisorbed UHMWPE (ultra-high-molecular-weight polyethylene) film on an Si surface. UHMWPE molecules containing carboxyl and hydroxyl chemical groups were chemisorbed onto an Si surface using an intermediate GPTMS SAM (glycidoxypropyltrimethoxy silane self-assembled monolayer) layer. The carboxyl and hydroxyl groups of UHMWPE molecules react with the terminal epoxy groups of GPTMS SAM during chemisorption. The resultant film (∼1.4 µm thick) has shown low coefficient of friction (∼0.1) and high wear life (exceeding 100,000 cycles) in a sliding test against a 4 mm diameter Si3N4 ball at a normal load of 0.3 N and a sliding velocity of 0.042 m/s measured on a micro-tribometer. In contrast, bare Si or GPTMS SAM modified Si has shown a higher coefficient of friction and failed within a few tens of sliding cycles. The high wear durability of the chemisorbed polymer film is attributed to the excellent adhesion of the UHMWPE film with the substrate due to chemisorption and to the good lubrication properties of UHMWPE molecules. This wear resistant film has potential applications in micro-electro-mechanical systems made of Si.
Thermochemistry of lanthanum zirconate pyrochlore
Authors: Radha A.V. , Ushakov Sergey V. , Navrotsky Alexandra
Published: October 2009

A thermodynamic study was carried out to resolve discrepancies in the enthalpy of formation and related parameters for lanthanum zirconate pyrochlore. The homogeneity field for single phase pyrochlore formation was determined to be ∼33–35 mol% La2O3 at 1500 °C. High-temperature oxide melt drop solution calorimetry was performed in sodium molybdate and lead borate solvents on three compositions ranging from La1.98Zr2.01O7 to La2.07Zr1.95O7. The enthalpy of formation from oxides at 25 °C, ΔH0f,ox, for stoichiometric lanthanum zirconate pyrochlore is −107.3 ± 5.1 kJ/mol, and the standard enthalpy of formation from elements, ΔH0f,el, is −4102.2 ± 6.0 kJ/mol. La2Zr2O7 pyrochlore was found by differential thermal analysis to be stable up to its melting point. The melting point and the fusion enthalpy of La2Zr2O7 pyrochlore were measured as 2295 ± 10 °C and ∼350 kJ/mol, respectively.
Nanostructural C-Al-N thin films studied by x-ray photoelectron spectroscopy, Raman and high-resolution transmission electron microscopy
Authors: Han Y.F. , Fu T. , Shen Y.G.
Published: October 2009

The effects of Al incorporation and post-deposition annealing on the structural properties of C-Al-N thin films prepared by reactive unbalanced dc-magnetron sputtering were investigated using x-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and high-resolution transmission electron microscopy (HRTEM). XPS studies demonstrated the presence of abundant Al-N bonds in addition to C-C and N-C bonds. At low incorporations of Al and N, the films were found to be essentially amorphous. By Raman and HRTEM, the formation of ∼5 nm fullerene-like carbon nitride (FL-CNx) nanostructures in an amorphous (C, CNx) matrix was evidenced with increasing Al content in the films. Crystalline improvement of FL-CNx nanostructures was seen, as well as the precipitation of ∼3–4 nm face centered cubic (fcc-) AlN nanograins by thermal annealing at 500 °C or above. Through these improvements, C-Al-N nanocomposite thin films were achieved. The effects of the incorporated Al and annealing on stabilizing fcc-AlN nanograins and FL-CNx nanostructures are elucidated and explained through the use of thermodynamic considerations.
High-resolution transmission-electron-microscopy study of ultrathin Al-induced crystallization of amorphous Si
Authors: Wang Zumin , Jeurgens Lars P.H. , Wang Jiang Y. , Phillipp Fritz , Mittemeijer E.J.
Published: October 2009

The process of ultrathin Al-induced crystallization of amorphous Si (a-Si) has been investigated by using high-resolution transmission electron microscopy and Auger electron spectroscopic depth profiling. Ultrathin Al overlayers, with thicknesses of 2.0 and 4.5 nm, have been shown to be capable of inducing full crystallization of an a-Si bottom layer as thick as 40 nm at temperatures as low as 320 °C. After full crystallization of a-Si, the Al of the original 2.0-nm Al overlayer completely moved through the Si layer, leaving a high-purity, large-grained crystalline Si layer above it. Such movement of Al also occurs for the originally 4.5-nm Al overlayer, but in this case the crystallized Si layer is relatively fine-grained and contains ∼5.0 at.% of residual Al nanocrystals distributed throughout the layer. The observations have been interpreted on the basis of sites available for nucleation of crystalline Si in the microstructure of the Al/Si layer system upon annealing.
Mesoporous Co–B amorphous alloy films with enhanced catalytic efficiency prepared from a mixed-surfactant solution
Authors: Li Hui , Liu Jun , Yang Haixia , Li Hexing
Published: October 2009

Co–B films were synthesized through the solvent evaporation-assisted chemical reduction method by using a mixed-surfactant solution containing Span 40 and (1S)-(+)-10-camphorsulfonic acid. With the characterization of x-ray diffraction, selected-area electron diffraction, x-ray photoelectron spectroscopy, scanning electron micrography, and transmission electron micrography, the resulting Co–B films were identified to be amorphous alloys with mesoporous structure. The synergistic effect of two kinds of surfactants is essential for the formation of mesoporous structure. During liquid-phase cinnamaldehyde hydrogenation to cinnamyl alcohol, the mesoporous Co–B amorphous alloy films exhibited a much higher activity and better selectivity than the solid Co–B nanoparticles prepared by direct reduction of cobalt ions with borohydride. The enhanced activity is attributed to both the mesoporous and the film structure, which provides more Co active sites for the adsorption and diffusion of reactant molecules. The improved selectivity may be related to the difference in surface curvature.
A thermally sensitive energy-absorbing composite functionalized by nanoporous carbon
Authors: Lu Weiyi , Punyamurtula Venkata K. , Han Aijie , Kim Taewan , Qiao Yu
Published: October 2009

A polypropylene-matrix composite material functionalized by nanoporous particulates was produced. When the temperature is relatively low, the matrix dominates the system behavior. When the temperature is relatively high, with a sufficiently large external pressure the polymer phase can be intruded into the nanopores, providing an energy absorption mechanism.
Mechanics-based analysis of selected features of the exoskeletal microstructure ofPopillia japonica
Authors: Cheng Liang , Wang Liyun , Karlsson Anette M.
Published: October 2009

We explore key mechanical responses of the layered microstructure found in selected parts of the exoskeletons (pronotum, leg and elytron) ofPopillia japonica(Japanese beetle). Image analyses of exoskeleton cross-sections reveal four distinct layered regions. The load-bearing inner three regions (exocuticle, mesocuticle, and endocuticle) consist of multiple chitin-protein layers, in which chitin fibers align in parallel. The exocuticle and mesocuticle have a helicoidal structure, where the stacking sequence is characterized by a gradual rotation of the fiber orientation. The endocuticle has a pseudo-orthogonal structure, where two orthogonal layers are joined by a thin helicoidal region. The mechanics-based analyses suggest that, compared with the conventional cross-ply structure, the pseudo-orthogonal configuration reduces the maximum tensile stress over the exoskeleton cross-section and increases the interfacial fracture resistance. The coexistence of the pseudo-orthogonal and helicoidal structures reveals a competition between the in-plane isotropy and the interfacial strength in nature’s design of the biocomposite.
Air-stable, unoxidized, hydrocarbon-dispersible boron nanoparticles
Authors: Van Devener Brian , Perez Jesus Paulo L. , Anderson Scott L.
Published: October 2009

Here we describe a simple method to produce boron nanoparticles with control over surface chemistry and dispersiblity in different solvents, with potential applications ranging from high energy density fuels to neutron capture therapy. The methodology should be adaptable to many hard materials; indeed, we have produced hydrocarbon-dispersible silicon nanoparticles using a procedure similar to that described below. The method, based on high-energy milling, with subsequent sedimentation to separate aggregates, produces gram quantities of nanoparticles in a narrow distribution of particle sizes centered around 50 nm, and should be readily scalable to industrial scale production.
Effects of sample geometry on deformation modes of bulk metallic glasses at the nano/micrometer scale
Authors: Ye Jianchao , Lu Jian , Yang Yong , Liaw Peter K.
Published: October 2009

Intense debates have been prompted concerning whether homogeneous deformation can be achieved in bulk metallic glasses at room temperature through the suppression of shear bands at the submicron scale. In this short communication, we demonstrate that multiple shear banding can be successfully attained via a proper modification of the microsample geometry, resulting in the appearance of a homogeneous deformation mode at the submicron scale. However, the apparent deformation homogeneity in our microcompression experiment is a manifestation of the sample geometry effect on the propagation rather than nucleation of shear bands.
Unidirectional solidification of Zn-rich Zn-Cu hypoperitectic alloy
Authors: Kaya Hasan , Engin Sevda , Böyük U. , Çadırlı Emin , Maraşlı Necmettin
Published: October 2009

Zn-0.7 wt.% Cu-hypoperitectic alloy was prepared in a graphite crucible under a vacuum atmosphere. Unidirectional solidification of the Zn-0.7 wt.% Cu-hypoperitectic alloy was carried out by using a Bridgman-type directional solidification apparatus under two different conditions: (i) with different temperature gradients (G = 3.85–9.95 K/mm) at a constant growth rate (41.63 μm/s) and (ii) with different growth rate ranges (G = 8.33–435.67 μm/s) at a constant temperature gradient (3.85 K/mm). The microstructures of the directionally solidified Zn-0.7 wt.% Cu-hypoperitectic samples were observed to be a cellular structure. From both transverse and longitudinal sections of the samples, cellular spacing (λ) and cell-tip radius (R) were measured. The effects of solidification-processing parameters (G and V) on the microstructure parameters (λ and R) were obtained by using a linear regression analysis. The present experimental results were also compared with the current theoretical and numerical models and similar previous experimental results.
Extensive deformation behavior of an all-oxide Al2O3-TiO2 nanostructured multilayer ceramic at room temperature
Authors: Dericioglu Arcan F. , Liu Y.F. , Kagawa Yutaka
Published: October 2009

An all-oxide Al2O3-TiO2 ceramic multilayer composed of 10–100 nm thick alternating layers was fabricated using the reactive magnetron sputtering process. Microindentation tests were carried out on the multilayer ceramic followed by microstructural observations of the cross-sections of the indented sites to characterize the indentation response of the system. During the observations, it was noted that an extensive room temperature “deformation” occurred in the multilayer ceramic material. The material shows a thickness reduction of as much as ∼40% under a conical indenter at 300 mN of load without microcracking and dislocation-assisted deformation. The room temperature deformation mechanism is governed by the relative movement and rearrangement of the anisotropic nanoscale columnar grains along the intergranular boundaries containing elongated voids. The relative sliding along the intergranular boundaries, and the subsequent granular rotation under indentation were well captured by finite element simulation.
Is there a hexagonal-close-packed (hcp) → face-centered-cubic (fcc) allotropic transformation in mechanically milled Group IVB elements?
Authors: Seelam Uma M.R. , Barkhordarian Gagik , Suryanarayana Challapalli
Published: October 2009

Allotropic hexagonal-close-packed (hcp) → face-centered-cubic (fcc) transformations were reported in Group IVB elements titanium (Ti), zirconium (Zr), and hafnium (Hf) subjected to mechanical milling in a high-energy SPEX shaker mill. Although the transformation was observed in powders milled under regular conditions, no such phase transformation was observed when the powders were milled in an ultrahigh purity environment by placing the powder in a milling container under a high-purity argon atmosphere, which was in turn placed in an argon-filled glove box for milling. From a critical analysis of the results, it was concluded that the hcp → fcc phase transformation was, at least partially, due to pick-up of interstitial impurities by the powder during milling of these powders to the nanocrystalline state.
War Is Culture: Global Counterinsurgency, Visuality, and the Petraeus Doctrine
Authors: Mirzoeff Nicholas
Published: October 2009

In one of his signature reversals of accepted wisdom, Michel Foucault modulated Carl von Clausewitz's well-known aphorism on war and politics to read, “Politics is the continuation of war by other means” (48). That is to say, even in peace, the law is enacted by force. In conditions of state-determined necessity, that force appears as a direct actor in legitimizing what Giorgio Agamben calls “the state of exception.” In English law the term would be “martial law” (Agamben 7). By extension, if globalization has again become the “global civil war” (Arendt, qtd. in Agamben 1) that was the cold war or has created a new state of “permanent war” (Retort 78), then war is global politics. So what kind of war is the war in Iraq (Reid)? It is now being waged by the United States as a global counterinsurgency. In the field manual Counterinsurgency issued by the United States Army in December 2006 at the instigation of General David Petraeus (Bacevich), counterinsurgency is explicitly a cultural war, to be fought in the United States as much as it is in Iraq. Cultural war, with visuality playing a central role, takes “culture” to be the means, location, and object of warfare. In his classic novel 1984, George Orwell coined the slogan “war is peace” (199), anticipating the peacekeeping missions, surgical strikes, defense walls, and “coalitions of the willing” that demarcated much of the twentieth century. In the era of United States global policing, war is counterinsurgency, and the means of counterinsurgency are cultural. War is culture. Globalized capital uses war as its means of acculturating citizens to its regime, requiring both acquiescence to the excesses of power and a willingness to ignore what is palpably obvious. Counterinsurgency has become a digitally mediated version of imperialist techniques to produce legitimacy. Its success in the United States is unquestioned: who in public life is against counterinsurgency, even if they oppose the war in Iraq or invasions elsewhere? War is culture.
War Poems from 1914
Authors: Ben-Merre David , Scholes Robert
Published: October 2009

In October 1912 the first issue of Harriet Monroe's new journal, Poetry: A magazine of verse, appeared. The last has yet to come. In an era when little magazines came and went like mayflies, Poetry came and has refused to go. The journal had it all—in its early years it was at the forefront of debates about imagism, vers libre, and other issues concerning the “proper” form and content for poetry. Monroe, its editor, is still insufficiently appreciated as a major figure in literary modernism. We hope to change that. Supported by a grant from the National Endowment for the Humanities, the Modernist Journals Project (MJP) has completed a digital edition of the first eleven years of this distinguished journal, using original copies provided by the University of Chicago Library, supplemented in some instances by copies from the University of Wisconsin, Madison, and the University of Tulsa's McFarlin Library. Those of us working on this edition have discovered many interesting things, including the first publication of Joyce Kilmer's “Trees,” which Cleanth Brooks and Robert Penn Warren later used as the primary example of bad poetry in their New Critical textbook, Understanding Poetry (274–78).
The Library of Congress Variant of “The Shield of Achilles”
Authors: Auden W. H. , Severn Stephen E.
Published: October 2009

As part of poetry magazine's annual poetry day, wealthy patrons of the arts gathered in chicago on 19 november 1960 for a private auction of books and manuscripts that benefited the Modern Poetry Association. Among the items available for bidding were handwritten fair copies of W. H. Auden's “The Shield of Achilles,” “Musée des Beaux Arts,” and “The Unknown Citizen,” all on 8½-by-11-inch sheets of unlined white typing paper, the poet's signature conspicuously appended to the bottom right corner of each page. Having been recognized earlier in the day as Poetry's “Poet of Honor,” Auden had written the copies for the charity event. Hyman J. Sobiloff, a successful industrialist and published poet, purchased the collection for one thousand dollars. In January 1961, he donated the pieces to the Library of Congress, where they remain to this day. At the time, the collection proved somewhat newsworthy: Poetry, the Chicago Tribune, the Washington Post and Times-Herald, and the Library of Congress Information Bulletin all ran brief articles on the auction and donation. Since then, however, the documents have been essentially lost to history. Few, if any, other written records of them remain, Auden's biographers have ignored the manuscripts, and no critical analysis of their content has yet been published.
Regarding the Pain of Women: Questions of Gender and the Arts of Holocaust Memory
Authors: Young James E.
Published: October 2009

My Title, a variation on Susan Sontag's regarding the pain of others, is meant as an homage to sontag and as an extension of her searing critique of war photography and its reflexive objectification of suffering, its conversion of victims into objets d'art. But why, in particular, the pain of women Holocaust victims here? Because we have finally begun to amass a large and profound critical literature on gender and the Holocaust, which, alongside Sontag's work on photography, might help us look at how and why the public gaze of photographers, curators, historians, and museumgoers continues to turn women into objects of memory, idealized casts of perfect suffering and victimization, and even emblems of larger Jewish suffering during the Holocaust.
Martial Art
Authors: Brown Bill
Published: October 2009

A large crowd stood around, enjoying the dancing magic, as in the middle two acrobats led on the dance, springing, and whirling, and tumbling.

—Homer, The Iliad

Western Literature's most magnificent object stages an intimacy between struggle and tranquillity. A gift to no soldier, but to his mother, requiting her ancient kindness, the shield of Achilles proffers a drama of war and of peace. The city of peace vibrates with the sound of flute and lyre, a wedding celebration, deliberations at assembly; the city of war quivers with well-armored soldiers, women and children perched atop the walls, beyond the walls an ambush laid along the river just where flocks of cattle come to drink (Il. 18.478–608). Homer teaches this truth about the object world: in the moment of their manufacture, weapons already manifest both prosperity and pain, technology and ceremony. Sweating, and longing, and grieving; springing, and whirling, and tumbling. The worlds inscribed on the shield figure those worlds out of which weaponry as such is forged. Could some new ekphrastic pedagogy disclose such worlds in the Hummer, the Abrams tank, the M-16, the B-52—revealing the quotidian histories they both congeal and obscure? If not, must we settle for Auden's lament, the mother pained now by what, for modernity, the god has wrought: “there on the shining shield / His hands had set no dancing-floor / But a weed-choked field” (294 [“The Shield of Achilles”]). Is the modern artifact so bereft of people?
Dismantling Heroism: The Exhaustion of War in Don Quijote
Authors: Fuchs Barbara
Published: October 2009

A la guerra me llevami necesidad;si tuviera dinerosno fuera en verdad.My poverty takes me off to war;if I had money, believe me, I wouldn�t go.

War is everywhere and nowhere in don quijote. It consumes don quijote's thoughts but seldom appears in the guise he expects. War animates the protagonist's most elaborate, potent fantasy of self-aggrandizement and social climbing, in which he lends his strong arm to a king to help him fight his wars and is rewarded with the king's daughter (Cervantes, Don Quijote 211–15). Yet as Don Quijote sets about trying to make his name through daring feats, actual war seems both elusive and overwhelming. Instead, Cervantes gives us a series of fantasies that ironize the conventional representation of heroism in a romance key, registering the anachronism of the single knight in a world marked by the collective allegiances of epic. At the same time, through a series of burlesque battles, the text reflects on the incommensurability of humanist pieties about war and its actual experience. Finally, in its engagement with problems of religious and ethnic difference, Don Quijote registers the contrast between war as it might be and the conflicts Spain actually experienced both within and beyond its borders.
The Thug, the Barbarian, and the Work of Injury in Imperial Warfare
Authors: Liu Lydia H.
Published: October 2009

In the modern english lexicon, the curious wordthugis usually traced to Hindi. In the early days of the antithug military campaign in India, William Henry Sleeman, the British architect of the campaign, brought out a thug lexicon entitledRamaseeana; or, A Vocabulary of the Peculiar Language Used by the Thugsin 1836. This lexicon represents the first systematic attempt to identify who the thugs are and how they communicate with one another in secret society. It appears to provide hard linguistic evidence for a newly discovered threat to the British presence in India, cobbling together a large collection of predominantly Hindi words and phrases and building them into a coherent image of the thug that attests to the authenticity of Hindu thuggism. The graphic details of thugs' cold-blooded strangling of innocent travelers are as numerous as the amount of verbs and nouns that have found their way into the book and into subsequent embellishments by popular media. That the wordthugis of Hindi origin (thag, theg, orthak) seems sufficient to prove that thugs exist and pose a threat. (Echoes of this argument can be found in the justifications for the United States–led war against the terrorist network al-Qaeda.) But as Martine Van Woerkens and other scholars have shown, thuggism was actually invented by the British who tried to seize criminal jurisdiction in areas that had been in the hands of the Mogul rulers. In the course of extending their control over a mobile population, the British used the construction of thug monstrosity to lay the foundation of “a ritual of conjuration” in the play of mirrors between them and the colonized (Van Woerkens 292).
1848/1898: Memorial Day, Places of Memory, and Imperial Amnesia
Authors: Greenberg Amy S.
Published: October 2009

Mr. Speaker, I believe that as we sow so shall we reap; and if in the minds of the present generation of boys and girls, young men and women, we sow the seeds of lukewarm patriotism, in the next we will reap a race of men and women who will care very little for love of country.…I would have this nation the absolute master of the commerce of the world. … [I]t is impossible to look up without having a feeling of pride steal over you for the patriots of '76, the sailors of '12, the boys in blue of '61, the courage of the boys in gray.…

—Representative Edmund H. Driggs to Congress, 8 March 1898

On 15 February 1898, the USS Maine exploded in Havana harbor, killing 266 crewmen. American journalists clamored for vengeance against the Spanish authorities they wrongly blamed for the accident. Three weeks later the Fifty-Fifth Congress unanimously voted in support of President McKinley's $50 million bill for the “national defense” (Morgan 275). By May, Spain and the United States were at war.
Quantification of geosynthetic behavior
Authors: Giroud J. P.
Published: October 2009

This paper presents state-of-the-art examples to show that, in a wide variety of cases, the behavior of geosynthetics can be quantified using theoretical analyses. Seven examples are reviewed: geotextile filter retention, geotextile filter clogging, geomembrane stress–strain behavior, geomembrane strain concentrations, geomembrane stress cracking pattern, geomembrane wrinkles, and geosynthetic resistance to differential settlement. The selected examples are such that the important behavioral aspect is not the behavior of the structure in which the geosynthetic is incorporated, but the behavior of the geosynthetic itself. In each case, the phenomenon or problem is described, the theoretical analysis is presented, and the results are discussed. An important message conveyed by this paper is that the solution of engineering problems can only result from rational analyses, not from common sense. Note: This paper is an updated version of a paper initially published as a Special Lecture in the proceedings of the Fifth International Conference on Geotextiles Geomembranes and Related Products, held in Singapore in 1994.
Assessing the performance of prefabricated vertical drain with vacuum and heat preloading
Authors: Saowapakpiboon J. , Bergado D.T. , Thann Y.M. , Voottipruex P.
Published: October 2009

ABSTRACT: This paper presents the effects of vacuum and heat preloading of a prefabricated vertical drains (PVD) that are used to accelerate consolidation of soft Bangkok clay. Laboratory model tests were conducted in small-scale consolidometers with undisturbed and reconstituted specimens of untreated (PVD), vacuum-treated (vacuum-PVD) and temperature treated (thermo-PVD) materials. The flow parameters were back-calculated using the Hansbo (Ground Engineering, 12, No. 5, 16–25, 1979) method in terms of the horizontal coefficient of consolidation (Ch) and the ratio of the horizontal hydraulic conductivity in the undisturbed zone (Kh) to the horizontal hydraulic conductivity in the smear zone (Ks) or (Kh/Ks). From the results of the laboratory tests, the increased hydraulic conductivity of the smear zone of undisturbed specimens using vacuum-PVD and thermo-PVD resulted in a decrease in Kh/Ks of about 11 and 12%, and an increase in Ch of 2 and 13%, respectively. On the other hand, the increased hydraulic conductivity of the smear zone of the reconstituted specimens using vacuum-PVD and thermo-PVD resulted in a decrease in Kh/Ks of about 20 and 22%, and an increase in Ch of 34 and 54%, respectively. The horizontal coefficient of consolidation of PVD with vacuum pressure was higher than for the untreated PVD due to the increased horizontal hydraulic conductivity in the smear zone. In addition, the higher temperatures led to reduced viscosity of water, which was attributed to the increase in the horizontal hydraulic conductivity within the smear zone surrounding the PVD. The high temperatures combined with PVD yielded faster rates of consolidation and higher magnitudes of settlement.
The Early History of Circular Sliding Surfaces
Authors: Petterson Knut E.
Published: October 2009

Synopsis

The Paper describes the work at Gothenburg leading to the introduction, in 1916, of the use of circular sliding surfaces in the analysis of stability problems in clay. This assumption has become very widely adopted, and the history of its early days is therefore a matter of considerable interest, both to specialists in soil mechanics and to civil engineers generally.

Ce document décrit les travax effectués à Gothenburg et qui ont conduit à l'introduction, en 1916, de l'emploi des surfaces de glissements circulaires pour l'analyse des problèmes de la stabilité dans l'argile. Cette hypothèse a été très largement adoptée par la suite et l'historique de ses débuts est done une question du plus grand intérêt à la fois pour les spécialistes de la mécanique du sol et pour les Ingénieurs du Génie Civil en général.
An Hydraulic Analogue Computer for Studying Diffusion Problems in Soil
Authors: Scott Ronald F.
Published: October 2009

Synopsis

Computing machines have become a familiar part of the modern world because of the need for practical, useful solutions to problems which are extremely difficult or impossible to solve mathematically. Such a need has arisen in the field of soil engineering, in areas where the foundation material is subject to freezing and thawing, situations in which heat transfer processes in the ground must be investigated.

An analogue computing device has been constructed in the Civil and Sanitary Engineering Department of the Massachusetts Institute of Technology, Cambridge, Mass., U.S.A., for the U.S. Army Arctic Construction and Frost Effects Laboratory to deal with non-linear diffusion problems of this nature, and this Paper describes its design and operation.

The use of the computer in the solution of consolidation problems. which are also diffusion phenomena, is briefly mentioned.

Les machines à calculer ont acquis une grande popularié dans le monde moderne vu le besoin de solutions pratiques aux problèmes extrêmement difficiles ou impossibles à résoudre mathématiquement. Un pareil besoin s'est présenté. dans le domain de la géotechnique là où le matériel de fondation est soumis an cycle du gel et du dégel, problème qui requiert l'étude de la transmission de chaleur.

Ce rapport décrit la construction et l'operation d'un appareil analogue à calculer qui a été construit pour solutionner de semblables problèmes diffusion non-rectilignes. L'emploi du calculateur aux solutions des problémes de consolidation, qui sont aussi des phénomènes de diffusion, est brièvement mentionné.
In-Situ Measurement of the Dynamic Properties of Soil by Vibration Methods
Authors: Jones Ronald
Published: October 2009

Synopsis

The Paper describes vibration methods which have been used to obtain the dynamic properties of soil in situ from measurements made at the surface.

Part I of the Paper considers the propagation of surface vibrations over test lengths of about 50 ft. It is shown that the dynamic shear modulus, and the form of its variation with depth, can be ascertained from measurements of the phase velocity of the surface vibrations within the frequency range of 35 to 400 c/s. The relation between phase velocity and frequency enables the depth to be found at which there is a marked change in elastic properties such as at a transition between clay and gravel.

In Part II of the Paper, a method is described for obtaining the dynamic shear modulus of the soil from the resonant frequency of a mass vibrating perpendicularly to the surface. This method enables localized measurements to be made which may be used to supplement the average data derived from the method described in Part I.

Le mémoire décrit méthodes de vibration qui ont été employées pour obtenir les propriétés dynamiques élastiques d'un sol in situ par des mesures faites Ala surface.

La première partie du mémoire examine la propagation des vibrations de surface sur des longueurs d'essai d'environ 15 m. On montre que l'on peut déterminer le module dynamique de cisaillement et la forme de sa variation suivant la profondeur, à l'aide de mesures de la vitesse de phase des vibrations de surface entre les limites de frèquence de 35 á 400 périodes par seconde. Le rapport entre la vitesse de phase et la frèauence permet de déterminer la profondeur à laquelle il y a un changement marqué des propriétés, comme dans le cas d'une transition entre argile et gravier.

Une méthode est décrite dans la deuxième partie du mémoire pour obtenir le module dynamique de cisaillement du sol à l'aide de la fréquence résonnante d'une masse vibrant perpendiculairement à la surface. Cette méthode permet d'effectuer des mesures localisèes qui peuveni. être utilisées pour suppléer aux données moyennes dérivées de la méthode décrite dans la premiére partie.
A Landslide in Boulder Clay at Selset, Yorkshire
Authors: Skempton A. W. , Brown J. D.
Published: October 2009

Synopsis

An analysis has been made of a long-term slip in a valley slope of the River Lune, near Middleton-in-Teesdale. The slip was entirely within a deposit of heavily overconsolidated intact boulder clay. Although a complete picture of the ground-water flow net was not obtained, sufficient information was nevertheless available to show that the field value of the cohesion intercept c′ was approximately equal to the laboratorv value measured in drained triaxial tests. This is in marked contrast to the results found from long-term slips in overconsolidated fissured clays.

Une analyse d'un glissement à long terme a été faite sur une pente de la vallée de la Lune, rivière voisine de Middleton-in-Teesdale. Le glissement s'est produit entièrement dans un dépôt d'argile de moraine à blocs intacts surconsolidée. Quoique l'on n'ait pas obtenu des renseignements complets sur le débit de l'eau souterraine, on a néanmoins rassemblé asset de renseignements pour montrer que la valeur sur le terrain de la section de cohésion c′ est à peu près égale à la valeur de laboratoire mesurée lors d'essais triaxiaux. Ceci est en opposition nette avec les résultats obtenus avec des glissements à long terme dans des argiles fissurées surconsolidées.
Measurement of Stresses in Rock
Authors: Karl Terzaghi
Published: October 2009

Synopsis

The rational design of permanent supports for tunnels and caverns in rock requires information concerning the initial state of stress in the rock surrounding the excavated space. In order to provide such information, tests have been carried out during the past three decades in a considerable number of tunnels and caverns for the purpose of determining the magnitude and orientation of the stresses which act in the rock adjacent to the cavity walls. However, even for a short length of tunnel, the scattering of individual values from the average is commonly so important that no reliable conclusions can be drawn concerning the initial state of stress in the rock adjacent to the station where the measurements were made. An exception to this generalization is found in the work of Nils Hast (1958) who measured the stresses in rock located beyond the distance to which the rock was damaged by blasting. This article contains a brief review of the short-comings of the data obtained from measurements on exposed surfaces, a description of Hast's procedures and a discussion of the benefits which can be derived from using his method of measurement in connexion with the design of the permanent lining of rock tunnels and caverns.

La conception rationnelle de supports permanents pour les tunnels et les cavernes dans le rocher demande une documentation sur la condition initiale de tension dans le rocher entourant l'espace excavé. Pour fournir ces renseignements, on a fait des essais pendant les trente dernières années dans un nombre considérable de tunnels et de cavernes afin de déterminer l'ampleur et l'orientation des tensions qui agissent dans le rocher adjacent aux murs de la cavité. Cependant, même pour une petite longueur de tunnell'écart des valeurs individuelles par rapport à la moyenne est généralement si grand qu'on ne peut tirer aucune conclusion sérieuse sur la condition initiale de tension dans le rocher adjacent à la station où les mesures ont été prises. On trouve une exception a cette généralisation dans les travaux de Nils Hast (1958) qui a mesuré les tensions dans le rocher situé au delà de la distance à laquelle le rocher a été endommagé par l'explosion. Cet article comprend un aperçu sur les imperfections des renseignements obtenus en mesurant les surfaces exposées, une description des méthodes de Hast, et une discussion sur les avantages que l'on peut obtenir en employant sa méthode de mesure en rapport avec la conception du revêtement permanent de tunnels et de cavernes dans le rocher.
Short-Term Stability of Slopes in Unweathered Jointed Clays
Authors: Esu F.
Published: October 2009

Synopsis

The short-term stability of the slopes in fissured and jointed stiff clays is analysed. The Author examines the behaviour of some typical Italian clays and points out the factors influencing the stability of cuts.

Considering some failures which occurred immediately after the end of excavations, it is concluded that jointed clays are more similar to jointed rocks than to soils. The behaviour of these clays depends on the resistance to sliding along the discontinuities, and the usual methods of stability analysis cannot be applied. Since water can seep through the discontinuities, jointed clays can be considered as permeable media and the hydrostatic pressure of the water contained in the discontinuities controls the stability of the slopes.

L'auteur examine la stabilité des talus artificiels en argiles consistantes et le comportement de quelques typiques argiles consistantes en Italie et analyse les facteurs qui déterminent la stabilité des talus.

Après avoir consideré les éboulements qui se sont verifiés immédiatement aprés la fin des certains travaux, l'auteur conclude qne les argiles fissurées consistantes presentent comportement plus voisin à celui des roches que à celui des sols. Le comportement des ces argiles est fonction de la résistence au glissement le long des surfaces de discontinuité; pourtant les méthodes normales de calcul pour les sols ne peuvent pas être appliquées dans ce cas.

Puisque l'eau peut circuler dans les fissurees, les argiles fissurées doivent être considerées des roches perméables; la stabilité des fouilles dépend de la pression hydrostatique de l'eau dans les fissures.
The Dynamic Penetration Test: A Standard that is not Standardized
Authors: Ireland H. O. , Moretto O. , Vargas M.
Published: October 2009

Synopsis

The Paper presents a description and a discussion of the technique of making the so-called standard penetration test as used in North and South America. Dynamic penetration tests such as the SPT are used widely in an effort to get results that can be interpreted by engineers on a universal basis. However, it has become evident that the results of the tests are often a compromise because of details in the test procedure which are generally not appreciated. It is common that those engaged in doing these tests change the procedure of the test or the dimensions of the tools and continue to call it standard, apparently unconscious that changes result in variations in the penetration resistance number N.

To describe the test and consider the various implications of the method properly the following items are considered independently: a procedure for boring, sounding and sampling which seems to be indicated for the test is described; the SPT in its original form is described in detail; as examples of variations, two modified and improved samplers and test procedures used in South America are mentioned; finally the applicability and the scope of the test are discussed.

Conflicting opinions between the Authors have arisen and their respective viewpoints are indicated.

L'exposé présente une description et une discussion sur la technique selon laquelle se fait le soidisant essai de pénétration standard, comme il est utilisé en Amérique du Nord et du Sud. Des essais de pénétration dynamiques tels que l'essai de pénétration standard sont largement utilisés pour tenter d'obtenir des résultats qui puissent être interprétés par les ingénieurs d'après une base universelle. I1 est toutefois devenu évident que les résultats des essais représentent souvent un compromis à cause de détails dans le processus d'essai auxquels on ne donne pas généralement leur valeur réelle. Il est courant que ceux occupeés à effectuer ces essais changent le processus de l'essai ou les tailles des outils et continuent à l'appeler ‘standard’, ignorant apparemment le fait que les changements résultent en des variations du nombre N de résistance à la pénétration.

Pour décrire l'essai et juger des différentes implications de la méthode de la façon qui convienne, les questions suivantes sont considérées indépendamment: on décrit un processus pour le forage, le sondage et l'échantillonnage qui paraît être indiqué pour l'essai; l'essai de pénétration standard dans sa forme originelle est décrit en détail; comme exemples de variations, on cite deux appareils de prise d'echantillon modifiés et améliorés et des processus d'essai utilisés en Amérique du Sud; on discute finalement des possibilités d'application et de la portée de l'essai.

Les Auteurs sont d'avis opposés et leurs opinions sont indiquées.
Incremental Numerical Solution of a Simple Deformation Problem in Soil Mechanics
Authors: Smith I. M.
Published: October 2009

Synopsis

During the past decade advances in the techniques of laboratory testing of soil materials have led to the development of constitutive theories which are perhaps lacking in generality and liable to modification as further experimental evidence comes to light. However, in principle they make possible the solution of some boundary value problems for soils throughout the range of deformations up to collapse. Concurrently computer-orientated methods of stress analysis have progressed to the point where the inherently non-linear, state dependent behaviour of soil continua can be treated on a step-by-step basis. This Paper brings together these two advances, in that the displacement finite element computation method is used to solve the boundary value problem of plane strain expansion of thick-walled hollow cylinders of soil. Drained cohesionless materials are assumed to deform consistently with the stress-dilatancy flow concept, and fully drained clays consistently with the Cam clay flow model. The predictions of the theories are compared with experimental results, and it is suggested that the approach serves as a complement to the usual limit analysis solutions prevalent in soil mechanics.

Au cours des dix dernières années, les progrès réalisés dans les techniques d'essais en laboratoire des matières du sol ont mené au développement de théories relatives à la constitution qui manquent peut-être d'une qualité de généralisation et peuvent subir des modifications à mesure que des témoignages expérimentaux ultérieurs apparaissent. Elles permettent cependant, en principe, de résoudre certains problèmes de valeur limite pour les sols dans la gamme entière des déformations jusqu'à l'affaissement. D'une façon correspondante, des méthodes utilisant des ordinateurs pour l'analyse des contraintes ont fait des progrès jusqu'au point où le comportement non linéaire d'une façon inhérente, dépendant de l'état des masses du sol, peut être traité sur une base allant de stade en stade. Le présent Exposé rapproche ces deux méthodes résultant des progrès réalisés, en ce que la méthode de calcul du déplacement de l'élément fini est utilisée pour résoudre le problème de la valeur limite de l'expansion de la déformation plane des cylindres de sol creux à paroi épaisse. Les matériaux drainés sans cohésion sont supposés se déformer d'une façon correspondant au concept du flux de dilatance par contrainte, et les argiles complètement drainées d'une façon correspondant à la maquette de flux à travers l'argile de Cam. Les prévisions des théories sont comparées aux résultats expérimentaux, et il est suggéré que la méthode d'étude sert à compléter les solutions par analyse à limite habituelle régnant dans la mécanique des Sols.
Harmonic rocking of rectangular foundations on a generalized Gibson stratum
Authors: Awojobi A. O.
Published: October 2009

The governing dual integral equations representing the mixed boundary value problem of the harmonic rocking of a rigid rectangular foundation on a generalized Gibson stratumhave been precisely formulated. The equations are shown to contain the same governing functions as in the corresponding axisymmetric problem. The work establishes that the unexpected result for the invariance of Gibson's Law (Awojobi, 1974a) is not a feature of the geometry of the foundation. Furthermore, the dominance of the surface shear modulus in the response of the foundation to harmonic excitation is not significantly affected by the stratum depth.

Sont formulées de façon précise les deux équations intégrales gouvernant le problème de la valeur de zone limitée mixte devant l'oscillation harmonique d'une fondation rigide rectangulaire posée sur une couche généralisée ‘Gibson’. On démontre que les dites équations sont pourvues des mêmes fonctions dirigeantes qui se trouvent dans le problème axi-symétrique connexe. Le travail établit que le résultat inattendu de l'invariance qui se produit d'après la Loi Gibson (Awojobi, 1974a) n'a aucun rapport avec la géométrie de la fondation. En outre, la dominance exercée par la module de cisaillement située à la surface sur la réaction ressentie à travers la fondation, suite a l'excitation harmonique, n'est pas atteinte de façon significante par la profondeur même de la couche.
Drawdown in embankments
Authors: Stephenson D
Published: October 2009

The recession of the phreatic line in an embankment following sudden drawdown of a reservoir is studied. The non-equilibrium equation for flow in porous media is simplified and solved to produce general charts indicating the variation of the water surface with time. Charts for the cases of a battered cut and a triangular embankment are presented. The point of emergence of the phreatic line is considered and the relationship between the storage coefficient and coefficient of consolidation is explained.

On étudie l'abaissement de la nappe phréatique dans un remblai à la suite d'un affaissement brutal d'un réservoir. L'équation de non-équilibre pour l'écoulement dans un milieu poreux est simplifiée et résolue pour produire des graphiques généraux indiquant la variation de la surface de l'eau avec le temps. Des graphiques pour les cas d'une coupe inclinée et d'un remblai triangulaire sont présentés. Le point d'emergence de la nappe phréatique est considéré et la relation entre le coefficient d'accumulation et le coefficient de consolidation est expliquée.