Contact Situations Research Articles

A Static Friction Model for Unlubricated Contact of Random Rough Surfaces at Micro/Nano Scale.

A novel static friction model for the unlubricated contact of random rough surfaces at micro/nano scale is presented. This model is based on the energy dissipation mechanism that states that changes in the potential of the surfaces in contact lead to friction. Furthermore, it employs the statistical theory of two nominally flat rough surfaces in contact, which assumes that the contact between the equivalent rough peaks and the rigid flat plane satisfies the condition of interfacial friction. Additionally, it proposes a statistical coefficient of positional correlation that represents the contact situation between the equivalent rough surface and the rigid plane. Finally, this model is compared with the static friction model established by Kogut and Etsion (KE model). The results of the proposed model agree well with those of the KE model in the fully elastic contact zone. For the calculation of dry static friction of rough surfaces in contact, previous models have mainly been based on classical contact mechanics; however, this model introduces the potential barrier theory and statistics to address this and provides a new way to calculate unlubricated friction for rough surfaces in contact.

Oppositional Identity and Back-Vowel Fronting in a Triethnic Context: The Case of Lumbee English

This study considers the dynamic trajectory of fronting of the back vowels boot and boat for 27 speakers in a unique, longstanding context of a substantive, triethnic contact situation involving American Indians, European Americans, and African Americans over three disparate generations in Robeson County, North Carolina. The results indicate that the earlier status of Lumbee English fronting united them with the African American vowel system, particularly for the boot vowel, but that more recent generations have shifted toward alignment with European American speakers. Given that the biracial Southeastern United States historically identified Lumbee Indians as “free persons of color” and the persistent skepticism about the Lumbee Indians as merely a mixed group of European Americans and African Americans, the movement away from the African American pattern toward the European American pattern was interpreted as a case of oppositional identity in which Lumbee Indians disassociate themselves from African American vowel norms in subtle but socially meaningful ways.

Bidirectionality of language contact: Spanish and Catalan vowels

The disproportionate number of studies in Barcelona and the Balearic Islands observing Spanish contact effects in Catalan production, rather than Catalan contact effects in Spanish production, is an oversight of bidirectionality and the probabilistic nature of social factors in situations of language contact. Accordingly, the present study analyzes both Catalan and Spanish mid front vowel production data from Barcelona to investigate whether Catalan contact effects occur in Spanish via a process of dissimilation, and whether such effects are strengthened in younger speakers due to the relatively recent implementation of Catalan linguistic policy in the educational and public spheres. The results are suggestive of dissimilation, where phonetic distinctions are maintained between Spanish /e/ and the two Catalan mid front vowels across both F1 and F2. Additionally, analyses of variance across F1 and F2 reveal that Spanish /e/ productions across F1 are more diffuse in younger speakers and Catalan mid front vowels across F2 are less diffuse, providing evidence of reciprocity in contact effects. These results underscore the bidirectional nature of language contact and advocate for the use of variance of F1 and F2 as a metric of phonological contact effects.

THE LINGUISTIC ADAPTION IN AN IMMIGRANT LANGUAGE SETTING IN MAKASSAR, INDONESIA

Historically, the immigrant has been living and interacting with Makassar people and others in Makassar since 2014 until today. These interactions result unique way of how these immigrant use language to communicate. This article mainly aimed to describe how was the language used among immigrant in Makassar. The data were collected through observation by recording the conversation and interviewing some of the participants to confirm how and why they used certain dialect during the conversation. These interactions by using some language variation or dialects can be called a language contact situation. In their early presence that immigrant used English (Eng) and Indonesia language (IL) formally to communicate with IOM staff, UNHCR staff, among immigrant, and out of them, but when they have access to live for a while in Makassar, they interact with Makassar people freely and they use various languages such as Makassar language (ML), Indonesian language by Makassar Malay language (MML) as the trend of Makassar dialect, or sometimes used English as their language code. MML was mostly used compared to other language by those immigrants in some public area in Makassar. The using of MML by immigrant was a linguistic adaptation to the target language.

Convivial linguistic practices: lived togetherness through language in the United Arab Emirates

Abstract This paper takes up conviviality as an analytical tool to investigate everyday language choices made by foreign residents living in Ras Al Khaimah, a small city in the United Arab Emirates (UAE). It draws on recent work in human geography and cultural studies to understand conviviality in terms of practices rather than outcomes. Specifically, it investigates some of the linguistic dimensions of conviviality deployed by residents of the city in everyday situations of linguistic contact and negotiation of difference. The paper focuses on participants’ “small story” narratives (Georgakopoulou, Alexandra. 2015. Small stories research: Methods – analysis – outreach. In Anna De Fina & Alexandra Georgakopoulou (eds.), The handbook of narrative analysis, 255–272. Malden: John Wiley & Sons) that exemplify everyday language choices in the face of a highly ethnolinguistically diverse as well as racially and economically stratified society. Considering the multitude of ethnolinguistic and socioeconomic divisions in the city and the country as a whole, the paper unpacks how such cross-border contact is negotiated through everyday language practices. The paper identifies four types of convivial linguistic practices described by my participants: language sharing, benevolent interpretation, language checks and respectful language choices. In the process, I also probe the limits of what studying conviviality can tell us about everyday linguistic togetherness in highly segregated societies marked by stark inequalities.

Contact Stiffness Model of Joint Surface Considering Continuous Smooth Characteristics and Asperity Interaction

A new model to accurately obtain the contact stiffness of the mechanical joint surface is established, which satisfies the continuous smooth contact characteristics of the asperity and also considers the influence of the asperity interaction. In order to satisfy the continuous and smooth contact characteristics of the asperity, the interpolation interval of the Hermite polynomial function is improved to make the asperity contact stiffness curve smoothly transition in the elastic, elastoplastic and completely plastic stages. Further, the contact situation of the joint surface considering the asperity interaction is explored through micro-contact analysis and mechanism research. Finally, using statistical principles, the microscopic contact model is extended to the entire joint surface, and the contact stiffness model of the joint surface is established. The simulation results show that the asperity stiffness model satisfies the continuous smooth contact characteristics. Surface roughness is the main factor that affects the contact stiffness, and the influence of the asperity interaction cannot be ignored.

Cognate similarity and intervocalic /d/ production in Riverense Spanish

Aims and objectives:While previous research has shown that phonetic variation in language contact situations is affected by whether a word has a cognate in the contact language, this paper aims to show that such an effect is not monotonic. According to the usage-based model, items in memory are organized according to similarity, thus we anticipated that formally more similar cognates would show a stronger cognate effect.Methodology:This variationist sociophonetic study investigates the relationship between cognate similarity and phonetic realization. We examined this relationship in the bilingual community of Rivera, Uruguay, in which both Portuguese and Spanish are spoken with regularity. Specifically, we focused on intervocalic /d/, which in monolingual Spanish is realized as an approximant [ð̞] or phonetic zero, but in monolingual Brazilian Portuguese is produced as a stop [d] or, in most varieties, an affricate [ʤ] before [i].Data and analysis:We analyzed a corpus of sociolinguistic interviews of the Spanish spoken in Rivera. Acoustic measurements were taken from approximately 60 tokens each from 40 different speakers. Using a linear mixed-effects model, we examined the relationship between several predictors and the degree of constriction of intervocalic /d/.Findings/conclusions:While there is an overall frequency effect whereby more frequent words exhibit less constriction of intervocalic /d/, as both frequency and cognate similarity increase, less constriction of intervocalic /d/ obtains. Therefore, frequent cognates in Portuguese that have very similar forms affect the production of intervocalic /d/ more so than other cognates.Originality:No previous study has demonstrated that the cognate effect on phonetic variation in a situation of language contact is regulated by form similarity between cognate pairs.Significance/implications:The data support the usage-based model in that similar cognates have more lexical connections and can therefore show greater influence on phonetic realization than can cognates that share less phonetic material.

Antimicrobial Copper Surfaces: Increasing Antibacterial Efficiency of Cu Surfaces by targeted Surface Functionalization via Ultrashort Pulsed Direct Laser Interference Patterning (Adv. Mater. Interfaces 5/2021)

In article 2001656, Daniel W. Müller and co-workers were able to significally enhance antibacterial efficiency of Cu surfaces against Escherichia coli by ultrashort pulsed laser interference patterning in the scale of single bacteria cells. Improved bacterial killing could mainly be attributed to increased Cu sensitivity due to altered contact situations involving both available contact area and surface wettability.

РЕАЛИЗАЦИЯ ФУНКЦИОНАЛЬНОГО ПОДХОДА ПРИ ОБУЧЕНИИ УСТНЫХ ПЕРЕВОДЧИКОВ

The article deals with the problem of implementing a functional approach in the training of interpreters. The significance of this approach is due to the need to form in them a conscious attitude to the translated text and the communicative situation of its creation, as well as to a reasonable choice of translation strategies and tactics. The article presents a retrospective of the functional approach emergence and development on the example of scientists from West Germany and Russia, and modern approaches to its implementation on the example of texts of various genres translations into Chinese and Arabic. The author considers the possibility of implementing a functional approach in the training of interpreters, especially at the stage of learning and preparation for interpretation. Namely, instructions to analyze external and internal factors of the source and target texts generation in a situation of excursion and to working with the function diagram of the dialogue in the situation "Meeting at the airport" are presented. The author draws a conclusion that while teaching interpreters, it is necessary to pay attention to the specifics of the oral, multimodal translation discourse, the status-role and communicative characteristics of the participants, the contact situation and the sphere of communication. The main provisions and conclusions of the article can be used by teachers of translation in the process of preparing students for future translation activities.

Robotic assembly of timber joints using reinforcement learning

In architectural construction, automated robotic assembly is challenging due to occurring tolerances, small series production and complex contact situations, especially in assembly of elements with form-closure such as timber structures with integral joints. This paper proposes to apply Reinforcement Learning to control robot movements in contact-rich and tolerance-prone assembly tasks and presents the first successful demonstration of this approach in the context of architectural construction. Exemplified by assembly of lap joints for custom timber frames, robot movements are guided by force/torque and pose data to insert a timber element in its mating counterpart(s). Using an adapted Ape-X DDPG algorithm, the control policy is trained entirely in simulation and successfully deployed in reality. The experiments show the policy can also generalize to situations in real world not seen in training, such as tolerances and shape variations. This caters to uncertainties occurring in construction processes and facilitates fabrication of differentiated, customized designs.

Control-Oriented Characterization of Product Properties during Hot Hole-Flanging of X46Cr13 Sheet Material in a Progressive-Die

Robust and versatile production is enabled by a closed-loop control of product properties. This essentially relies on the characterization of the interaction between properties and available degrees of freedom to control the process. In particular, this work examines the setting of collar height, thinning, curvature, and hardness during hot hole-flanging of X46Cr13 sheet material with simultaneous heat treatment to identify approaches for a closed-loop property control in hot hole-flanging during multi-stage hot sheet metal forming. To scrutinize the adjustability of the hardness of X46Cr13 sheet material by heat treatment with rapid heating and short dwell times, quenching tests with austenitizing temperatures from 900 to 1100 °C and dwell times from 1 to 300 s were carried out. A hardness between 317 and 680 HV10 was measured. By analyzing the force-displacement curve and the contact situation between tools and blank during hot hole-flanging, an understanding for the process was established. To determine the adjustability of geometrical collar properties and the hardness of the collar, collars were formed at punch speeds between 5 and 100 mm/s and at different temperatures. Here, a dependency of the geometry of the collar on temperature and punch speed as well as setting of the hardness was demonstrated.

Management of native and exotic plant species with edible fruits in a rural community in a protected area of NW Patagonia

Management practices are very sensitive to socio-environmental change and the influence of market society. This case study was carried out in the Cuyín Manzano rural community, situated in a protected area within the North Patagonian UNESCO biosphere reserve. We investigate the differential practices applied by the community with regard to management of native and introduced species with edible fruits using semi-structured and free interviews in 11 homes (80%). A Participatory Rural Appraisal (PRA) was also performed to validate the field results. The data was analyzed quali-quantitatively, in the latter case with Generalized Linear Models. A total richness of 27 species was found, of which 11 were native and 17 introduced. Native plants were mainly managed by gathering and tolerance, while exotic species were not only harvested, but also protected, sown and transplanted, and plants inherited from forebears were cared for. Management intensity varied according to origin, being greater for the introduced species. In addition, the species of greater cultural importance were also those which experienced a higher number of management practices, with possible processes of incipient domestication being particularly notable for two native plants. Exotic plants have a higher probability of being managed, and with greater intensity, than native ones, even though the latter have had a much longer history of use. Our results show patterns of diversification of edible fruit species through different management practices. For inhabitants, these practices represent significant situations of contact with nature, which enable traditions based on local knowledge to be maintained.

Diplomatic Gifts as Ordering Devices

Summary This conclusion to the forum on diplomatic gifts goes on to note two historical types of such gifts. They are, first, fostering of a royal child at another royal court and, second, royal and noble marriage exchanges. Using these examples as a stepping stone, this essay goes on to formulate a co-ordination system of giver and receiver assessments of gift value, ranging from low to high. This yields four types of gifts: personalised gifts (low value to giver, high value to receiver); unique gifts (high value to both parties); culturally irrelevant gifts (high value to giver, low value to receiver) and fluff (low value to both parties). The essay hypothesises that polities that approach one another in a situation of contacts with low density will tend to aim for unique gifts, while polities whose relations are dense will aim for gifts that are of equal value to both parties.

Development and Optimization of a Tribometer for Radial Shaft Seals

Abstract In order to systematically investigate the tribological behavior of machine elements, several different tribometers based on simplifications of the contact situation have been developed and used successfully in the past. Many of these tribometers have become a standard testing equipment for tribologists. For the contact of radial shaft seals (RSSs), currently no such tribometer exists that can be used to characterize their behavior in a satisfying manner. In this paper, a tribologically equivalent system for RSSs is presented. The contact between the sealing lip and shaft is reproduced using a ring-shaped sample prepared from elastomer test slabs of the respective application material in contact with a conical shaft. The cone angle is chosen to properly represent the contact angles of the RSS under investigation by means of finite element (FE)-simulation of the contact pressure. The test rig allows for the on-line determination of friction, contact temperature, and wear progress. Results show good agreement of friction coefficient and wear behavior for the pairing of two typical elastomers with synthetic and mineral-based lubricants.

Processing Q&P steels by hot-metal gas forming: Influence of local cooling rates on the properties and microstructure of a 3rd generation AHSS

Tube hydroforming is a well-established process in industry for producing complex shaped parts with closed cross section geometry and high geometrical accuracy. Hot-metal gas forming (HMGF) extends the conventional tube hydroforming process by a complex thermo-mechanical approach and thus potentially enables the complex processing of tubes from the relatively new class of quenching & partitioning-steels (Q&P steels). To prove the feasibility of an integrated Q&P treatment in the HMGF process, a simple demonstrator geometry is considered in the present study. The applied forming pressure is limited to 70 MPa, resulting in incomplete forming of the parts in the corner areas. The resulting, locally varying contact situation between workpiece and die allows the investigation of different cooling rates and their influence on local microstructural changes and on the corresponding mechanical properties. A numerical finite element simulation is used to estimate local cooling rates in three different areas of the tube (maximum cooling rates between 60 and 280 K/s), which are then correlated with hardness measurements and typical microstructural features. The hardness distribution is inhomogeneous over the cross section of the part (varies about 150 HV), with a minimum in the areas without die contact during quenching. Ferritic areas are observed in these regions due to the significantly lower cooling rates. Tensile tests show that the stress-strain behavior after the shortest partitioning time of 10 min is not only better from an energy efficiency point of view, but also provides both high strength (Rm =2050 MPa) and high ultimate strain (19.7 %), while longer partitioning times result in inferior properties. Thus, the present study shows that the Q&P treatment can be integrated into the HMGF process, but the local cooling rates must be taken into account as they strongly influence the final mechanical properties of the workpiece.

Modeling of 3D Surface Morphologies for Predicting the Mechanical Contact Behaviors and Associated Electrical Contact Resistance

The accurate estimation of real contact area plays an important role in predicting the mechanical contact situation and associated electrical contact resistance for engineering rough surfaces. In this work, an improved peak identification method is proposed to reconstruct the rough surface morphologies numerically. A universal calculation process of real contact area and load force under the progressive indentation depth for rough surfaces is developed. Furthermore, a three-dimensional finite element model for analyzing the mechanical contact problem is built and the electromechanical coupling simulation results are compared with that obtained by our novel calculation method. The proposed solution is beneficial for accurate calculation of contact area, which is featured by high aspect ratio in the case of micro-contact. The relationship between electrical contact resistance and load force is also captured in the initial contact process.

Language and Art in Senegal: The Crossbreeding of Identities in Music

Senegal is a melting pot of several civilizations mainly originated from the West (Europe) and the East (the Arab world). Assuming that language and culture are intrinsically related, the settlement of those people and their status as dominant minority sparked and strengthened the use of their languages in formal domains. In the long ran, as they became domesticated, thus now considered African languages because they have contributed to mold the cultural identity of younger generation, they involve in all linguistic interaction. Arab, in its classical form, remains a symbol of Islam which earns it a certain degree of sacredness. Nevertheless the contact situation with the other languages forced it to crossbreed in special ways like borrowings and interferences. As for the other foreign languages, namely French, English, Spanish, and German at a least extent, they are made to carry the weight of local cultures.

Taper junctions in modular hip joint replacements: What affects their stability?

BackgroundAlthough taper junctions are beneficial in the reconstruction of hip joints, some clinical concerns like the formation of adverse local tissue reactions have recently emerged. These reactions are associated with wear and corrosion products from the interface of insufficient taper connections regarding strength. Commonly used tapers vary in their geometric and topographical design parameter. Therefore, this study aims to evaluate interactions between design and surgical related parameters to the taper connection strength. MethodsIn this study, the effect of the taper contact situation, surface roughness and head material in combination with assembly force on the taper connection strength were assessed using torque-off tests. Furthermore, the type of use in terms of single-use or re-use of the stem taper was investigated. ResultsThe study showed that the impaction force is the predominant factor that determines the taper strength followed by the type of use and the head material. The contact situation seems to slightly influence the determined torque-off moment, whereas the surface topography of the stem taper obviously plays a minor role for the taper connection strength. ConclusionClinical users should be aware that an increased assembly force will strengthen the stability of the taper junction, whereas care should be taken when reusing hip stems with metal heads as this may decrease their connection strength.

Collectivity, connectivity and control: reframing mass society in the digital era

ABSTRACT Mass society theory was originally a discourse on crowds, popular culture and revolutionary change. It portrayed the ideological control of the many by the few in situations of close contact without the complexities of mediated connectivity. The notion of social change was premised on analogue forms of collective behaviour within society rather than digital flows in networks. Reviving this theory in the digital era requires a reconsideration of connectivity and control transacted in mediated publics that support virtual gatherings centred on mass- self communication. Smartphones may be considered the iconic connectors that channel such communication. These electronic devices provide a vital understanding not only of the way information and communication technology is reshaping mass society but also the repositioning of the individual in networked relationships. It implies that mass in digitized environments is not simply a concept of nameless uniformity but one stressing the parasitic nature of networked connectivity. At the same time, it also suggests a connectivity made fragile by forms of remote control that are predatory on mass-self communication.

Basic pain terms in Beserman Udmurt

This paper is devoted to semantic structure and syntactic properties of predicates of pain in Beserman Udmurt. Beserman is a variety of Udmurt spoken in northwestern Udmurtia, which has undergone contact infl uence of Russian dialects and of Turkic languages. We analyze meanings and compatibility of units which denote pain, describe grammatical encoding of diff erent participants of the situation of pain — the experiencer, the body part where pain is located, and the cause of pain. We consider the following parameters to be relevant for encoding the situation of pain in Beserman Udmurt: type of experiencer, location of pain and its cause (including a human making someone feel pain), pure pain vs. pain accompanied by functionality loss, physical pain vs. painful emotions, intensity of pain and its type. We compare Beserman Udmurt data with those from idioms which either are closely related to Udmurt genetically or are in the situation of close contact with it — namely, with the data from Komi-Zyrian, certain Russian dialects, and Turkic languages. We show that unlike Komi-Zyrian, its relative, Beserman Udmurt encodes diff erent types of pain on the lexical level (i. e. by verbal roots and ideophones), not on the grammatical one (i. e. through morphological derivation). In this respect, Beserman Udmurt resembles certain Turkic languages. The diversity of argument encoding in expressions of pain is a common trait of Beserman Udmurt and Komi-Zyrian; it seems to be supported by the infl uence of Russian dialects.