Contact Situations Research Articles

Experimental Study on the Complex Contact Frictional Property of an Ultralong Distance Large-Section Concrete Pipe Jacking and Prediction of Pipe String Stuck

Line 2 of the Guanjingkou Pipe Jacking Project in Chongqing encountered a pipe sticking problem, whose occurrence was inevitably attributed to the higher total frictional resistance of pipe strings rather than the maximum jacking force. Line 1, which is about to start construction, has basically the same construction environment as Line 2 using the same microshield and pipe string sizes. To avoid repeating the pipe sticking problem of Line 2, the mutual friction characteristics between the surrounding rocks and jacked pipe strings are studied for Line 1 by adopting the same test method under seven complex contact conditions (the presence or various combinations of three substances, i.e., extrapipe string field debris, bentonite slurry, and sand-laden waste slurry, on the jacked pipe string-surrounding rock contact surface are mainly considered). The results show that sufficient bentonite slurry can effectively reduce the frictional resistance, and when the amount of bentonite is insufficient, the average friction coefficient (AFC) of the later contact surface increases by 50%∼70%. The comparison of the monitored versus predicted jacking forces indicates that the value predicted by the test is slightly higher than the monitored force and the variation trends of the two match well, thus proving the correctness of the test results. It is possible to continue predicting the variation trends of the jacking force and frictional resistance based on the contact situation outside the pipe string wall, which greatly lowers the probability of re-encountering pipe sticking. The test results not only explain the important role of bentonite slurry in reducing the pipe string wall frictional resistance but also suggest that an increase in the pipe string wall frictional resistance resulting from the complex contact inflow into the overexcavation gap is the root cause of pipe sticking; moreover, the number of jacked pipe strings matching a single IJS is the second cause of pipe string sticking. The methodology of this study can provide a reference for other studies concerning the jacking force of long-distance rock microshield tunnelling.

Emergency command path for Space Traffic Management

The availability of command time slots is a key factor in determining orbital spacecraft manoeuvre execution. Command paths are typically provided via existing ground infrastructure and set at pre-determined times with limited ability to react quickly. Collision avoidance manoeuvre commands may need to be sent many hours in advance, thus increasing decision uncertainty, and leading to higher overall risk in the space environment. With significantly more satellites expected in the next few years, the strain on ground infrastructure will only grow. In particular, the deployment of mega-constellations will radically increase conjunctions involving at least one active object, as well as conjunctions involving two active objects. Fortunately, Europe has infrastructure in place to provide an alternate or emergency command path for Space Traffic Management and collision avoidance on a global scale.The Galileo Navigation System has embedded in the Galileo Signal in Space (SiS) various data channels that are near real time, very reliable, and highly available anywhere in Earth orbit. Satellites equipped with a Galileo GNSS receiver are therefore not only provided with accurate positioning data, but also with the means to continuously receive commands, even in the event that nominal TT&C ability is impaired or lost. These channels would be limited to emergency commands (e.g. manoeuvres or loss of contact situations) and would not be intended for nominal commanding. The use of the Galileo SiS will allow operators to significantly extend the time taken to make manoeuvre decisions, wherever the satellite is located. As such, it would act as a backstop command path, thereby significantly enhancing global orbit protection. This paper provides information on current and planned collision avoidance programs, details about the SiS data channel, its possible implementation on-board the user spacecraft, potential ground interfaces, and operational considerations along with a request for industry feedback on its possible adoption.

Prevalence of Staphylococcus aureus carriage and pattern of antibiotic resistance, including methicillin resistance, among contact sport athletes in Italy.

Background and purpose: Athletes participating in contact or collision sports have a great chance of acquiring Staphylococcus aureus infections. The risk factors for colonization and infections include frequent antibiotic use, close contact situations, skin trauma, sharing of sports equipment, and poor hygiene. Therefore, our specific goals were to determine (1) prevalence of S. aureus among different types of contact sport athletes which were barely studied in the European region, (2) antimicrobial resistance of S. aureus isolates, and (3) association of carriage with particular risk factors of spor t practices.Patients and methods: A cross-sectional study was conducted among contact or collision sport athletes in Italy. A questionnaire was used to gather information about sociodemographic characteristics, specific sport activities, and participants’ health conditions. Swabs were collected from the nares, oropharynx, and fingers and tested for S. aureus isolation and antimicrobial susceptibility.Results: S. aureus was carried by 42% of 238 enrolled athletes. Colonization was associated with number of weekly training days, sharing of sports equipment, not taking a shower immediately after training, and a previous history of pharyngitis or sinusitis and skin manifestations. Isolates were resistant to clindamycin (24.8%) and erythromycin (15.8%). Of all athletes, 1.3% carried methicillin-resistant S. aureus (MRSA); MRSA were 3% of all S. aureus isolates. No strains were resistant to sulfamethoxazole/trimethoprim.Conclusion: Our results have shown a high prevalence of S. aureus carriage and a relevant resistance to antimicrobials used for the treatment of S. aureus infections. Prevention efforts aimed at reducing S. aureus colonization, and thus potentially reducing infections, should be improved.

Language contact does not drive gesture transfer: Heritage speakers maintain language specific gesture patterns in each language

This paper investigates whether there are changes in gesture rate when speakers of two languages with different gesture rates (Turkish-high gesture; Dutch-low gesture) come into daily contact. We analyzed gestures produced by second-generation heritage speakers of Turkish in the Netherlands in each language, comparing them to monolingual baselines. We did not find differences between bilingual and monolingual speakers, possibly because bilinguals were proficient in both languages and used them frequently – in line with a usage-based approach to language. However, bilinguals produced more deictic gestures than monolinguals in both Turkish and Dutch, which we interpret as a bilingual strategy. Deictic gestures may help organize discourse by placing entities in gesture space and help reduce the cognitive load associated with being bilingual, e.g., inhibition cost. Therefore, gesture rate does not necessarily change in contact situations but might be modulated by frequency of language use, proficiency, and cognitive factors related to being bilingual.

Tribological testing of leather surface coated with sputter-deposited Ti-Ag-O films

Abstract New leather treatment processes involving nanoparticles require new testing methods and procedures to evaluate their impact on human health. In the current work, the tribological properties of goat leather surfaces with sputter deposited Ti-Ag-O films were analyzed. A set of different polymer counter bodies was used to establish different tribological contact situations. A detailed analysis of the worn surfaces by scanning electron microscopy revealed details about the wear mechanisms ranging from abrasive to adhesive depending on the friction. Further, information about the formation of wear debris particles from the Ti-Ag-O films was obtained, in particular whether or not these particles were transferred to the counter body. The performed tests exemplify a possible testing procedure for leather treated with nanoparticles.

Prawo do opieki dyplomatycznej i konsularnej – przyczynek do rozważań w świetle standardu międzynarodowego

This article aims at analyzing the right to diplomatic and consular protection in the context of the standard resulting from international law. It tries to give a definition of this institution, pointing to its public and subsidiary nature. It also points out that diplomatic and consular assistance is carried out in a situation of conflict between the interests of the individual and the country of origin, and that of the host country. The article also discusses the subject and subject matter of consular and diplomatic care.
 Moreover, the study comments on the specific features of this right from the point of view of the complexity and effectiveness of the protection of rights at the international level. In this context it was pointed out that the right to diplomatic and consular protection is not a classic right, but can be considered as an instrument for the operation of other rights or freedoms. The right to consular and diplomatic care is devoid of homogeneous regulation, but also depends on the legal standard of care offered by the home state and must be within the limits set by the host country. The scope of its application may be related to any legal event that may occur when the entity is in a situation of contact with the legal system of the receiving state.
 The discussions under consideration highlighted the subsidiarity of the right to diplomatic and consular assistance for the exercise by the individual of his or her rights and freedoms. However, There is no complete protection standard in this respect, which is conducive to the lack of exhaustive regulation at the convention level, which, in extreme cases, can jeopardize the exercise by the individual of his or her subjective rights, that is to ensure its adequate protection standard in the territory of the host country.

Numerical simulation for an estimation of the jacking force of ultra-long-distance pipe jacking with frictional property testing at the rock mass–pipe interface

In ultra-long-distance rock micro-shield pipe jacking, the pipe wall friction resistance is a key factor that determines the magnitude of the jacking force and the layout of the intermediate jacking stations (IJSs), whereas the pipe-rock contact condition is the critical factor controlling the pipe string wall friction resistance. This paper aims to reveal the variation law of the friction resistance between the outer wall of a large-section of concrete pipe string and the surrounding rock during construction via ultra-long-distance rock micro-shield pipe jacking. To that end, the shear friction behaviour and mechanical mechanism was investigated between sandstone and concrete pipe string walls under seven different complex contact conditions (primarily considering various combinations of the three substances, namely, extra-pipe in situ debris, bentonite slurry and sand-laden waste mud at the pipe-rock contact surface) through direct rock shear tests based on the actual pipe-rock contact condition at the Guanjingkou Water Conservancy Project in Chongqing. The average friction coefficient (AFC) of the residual phase of the contact surface under 7 contact conditions was obtained by friction testing. Combined with the contact situation between the surrounding rock and pipe strings at the stage of a rapidly increasing jacking force, a three-dimensional finite element model was established, and the displacement control method was used to simulate the jacking. The comparison with the field monitoring results shows that the numerical model can accurately predict the jacking force and verify the reliability of the AFC parameters in the numerical calculation. Therefore, the combination of indoor testing and the finite element method can be applied to study the jacking force for other ultra-long rock micro-shield pipe jacking applications.

Turkish-Dutch bilinguals maintain language-specific reference tracking strategies in elicited narratives

Aim:This paper examines whether second-generation Turkish heritage speakers in the Netherlands follow language-specific patterns of reference tracking in Turkish and Dutch, focusing on discourse status and pragmatic contexts as factors that may modulate the choice of referring expressions (REs), that is, the noun phrase (NP), overt pronoun and null pronoun.Methodology:Two short silent videos were used to elicit narratives from 20 heritage speakers of Turkish, both in Turkish and in Dutch. Monolingual baseline data were collected from 20 monolingually raised speakers of Turkish in Turkey and 20 monolingually raised speakers of Dutch in the Netherlands. We also collected language background data from bilinguals with an extensive survey.Data and analysis:Using generalised logistic mixed-effect regression, we analysed the influence of discourse status and pragmatic context on the choice of subject REs in Turkish and Dutch, comparing bilingual data to the monolingual baseline in each language.Findings:Heritage speakers used overt versus null pronouns in Turkish and stressed versus reduced pronouns in Dutch in pragmatically appropriate contexts. There was, however, a slight increase in the proportions of overt pronouns as opposed to NPs in Turkish and as opposed to null pronouns in Dutch. We suggest an explanation based on the degree of entrenchment of differential RE types in relation to discourse status as the possible source of the increase.Originality:This paper provides data from an understudied language pair in the domain of reference tracking in language contact situations. Unlike several studies of pronouns in language contact, we do not find differences across monolingual and bilingual speakers with regard to pragmatic constraints on overt pronouns in the minority pro-drop language.Significance:Our findings highlight the importance of taking language proficiency and use into account while studying bilingualism and combining formal approaches to language use with usage-based approaches for a more complete understanding of bilingual language production.

Cross-correlated shot noise in three-terminal superconducting hybrid nanostructures

We work out a unified theory describing both non-local electron transport and cross-correlated shot noise in a three-terminal normal-superconducting-normal (NSN) hybrid nanostructure. We describe noise cross correlations both for subgap and overgap bias voltages and for arbitrary distribution of channel transmissions in NS contacts. We specifically address a physically important situation of diffusive contacts and demonstrate a non-trivial behavior of non-local shot noise exhibiting both positive and negative cross correlations depending on the bias voltages. For this case, we derive a relatively simple analytical expression for cross-correlated noise power which contains only experimentally accessible parameters.

Rolling fatigue life of PM steel with different porosity and surface finish

Gears made of PM steel are of interest for the automotive industry because they can be produced to near net shape with only a few processing steps.Automotive gears experience a complex contact situation with rolling as well as combined rolling and sliding. They also have to be able to withstand high loads and fairly high temperature variations.Earlier work show that the main limiting parameter of the contact fatigue life of PM steel is the porosity. A higher porosity/lower density will decrease the fatigue life of the PM component.In the present study, the pure rolling contact fatigue life of PM steel with different density and surface finish has been investigated. A rolling contact fatigue test rig, where rods of the tested material are mounted between two rolling wheels, was used. Two densities of PM steel, 6.8 and 7.15 g/cm3 and a full density reference steel with two different surface finishes, centerless grinded and superfinished, were tested. The tests were run for a given number of load cycles or until failure (fatigue life). SEM was used to study the surfaces and cross-sections to reveal the mechanisms of crack initiation and propagation.The higher density PM steel (7.15 g/cm3) outperformed the lower density steel (6.18 g/cm3) by a factor of around 4 in fatigue life at the same surface pressure, regardless of surface finish. Cracks are initiated at a depth of around 100 µm. These cracks propagate and eventually they reach the surface, causing surface damage and failure. For the low density PM steel, both sub surface crack initiation and failure occurred earlier (at a lower number of load cycles) than for the higher density PM steel.Severe surface damage or wear were not found until failure occurred. Still, some initial alteration of the surfaces was seen already after 0.5 million load cycles, in the form of removal of the highest asperity peaks on the centerless grinded surfaces, and opening of the surface pores on the superfinished surface. No effect of surface finish was found on the fatigue life. The difference in surface roughness could induce a difference in local stress concentrations at the surface, but in this test the cracks causing fatigue failure are initiated at a depth where the stress distribution is not affected by local surface stress concentrations. This means that for fairly smooth surfaces roughness, the surface of PM steel is not important when it comes to pure rolling fatigue life.

A usage-based approach to “language” in language contact

AbstractThe use of named languages is still prevalent in current contact linguistics research. In this paper, I argue that this cannot explain many contact situations and types of language knowledge. I propose a usage-based account of language instead which does not take linguistic systems for granted but construes them based on the single linguistic unit. A language is seen as a radially organized network of constructions, which are interlinked through co-use, which employ the same inventory of linguistic forms and which are appropriate in the same socio-pragmatic circumstances.

Simulation of Contact Area and Pressure Dependence of Initial Surface Roughness for Cermet-Coated Discs Used in Disc Brakes

Friction, wear, and emission performance strongly depend on the contact pressure and area at the interface of the pad and disc. The contact situation at the pad-to-disc interface can be explained b ...

Impact of stem taper damage on the fracture strength of ceramic heads with adapter sleeves

BackgroundUsing a new ceramic head with a titanium adapter sleeve offers the possibility of maintaining a well fixed stem when conducting cup revision of a total hip arthroplasty. The aim of this study is to test the impact of stem taper damage on the fracture strength of sleeved ceramic heads. MethodsPristine zirconia-toughened alumina heads with titanium adapter sleeves (BIOLOX®OPTION System) were tested on damaged Ti-4Al-6V stem tapers in accordance with ISO7206-10. Four distinctive damage types classified as intolerable by the manufacture were investigated, representing various reductions in contact area between the stem taper and sleeve taper as well as damage incurred from previous ceramic head fracture. FindingsThe largest reduction in fracture strength occurred for a loss of contact for the entire length of the stem taper. Nonetheless, the fracture strength in all investigated cases was several times higher than that defined by the FDA standards. InterpretationThe use of a titanium sleeve recreates a uniform contact situation between the ceramic head and the outer sleeve taper in situations of damaged stem tapers. For the investigated damage types a high fracture strength of the ceramic head was maintained. This study supports the clinical use for sleeved ceramic heads in instances of greater damages of stem tapers than previously defined in order to spare patients from stem removal.

Multilingualism at church: language practices in a Ghanaian context

ABSTRACTThis paper examines the linguistic repertoires and domains of language use of the members of Victory Baptist Church at Nkwantanang (a suburb of Kade), an Akan-speaking area in the Eastern Region of Ghana. Data for the study is from observations and transcribed recordings of Sunday services, youth and women fellowship meetings, as well as conversations and interviews with selected members of the church. The theoretical underpinning of the work derives from Fishman’s [(2006). A decalogue of basic theoretical perspectives for a sociology of language and religion. In T. Omoniyi, & A. J. Fishman (Eds.), Explorations in the sociology of language and religion (pp. 13–25). Amsterdam: John Benjamins Publishing Company. Retrieved from https://sociologyoflanguageandreligion.com/about/fishmans-decalogue/] sociology of language and religion principles and Baldauf’s [(2005). Micro language planning. In P. Bruthiaux, D. Atkinson, G. Eggington, W. Grabe, & V. Ramanathan (Eds.), Directions in Applied Linguistics: Essays in Honor of Robert B. Kaplan (pp. 227–239). Clevedon: Multilingual Matters] micro language planning approach. A major finding is that there are numerous instances of code-switching among the youth, which are attributable to the language contact situation in the church and the town. Additionally, monolingual elderly women resort to lexical borrowing. Furthermore, whereas some studies have proved that smaller communities are diglossic, this study shows that the language situation in Nkwantanang is rather multilingual despite the community's small size and remoteness. Lastly, members of the church have a positive attitude towards the prevailing language situation, which supports principle three of Fishman's SLR.

Nasal consonants block /o/ fronting in white and Lumbee speakers from Robeson County, North Carolina

This study examines /o/ fronting in white and Lumbee speakers in a tri-ethnic contact situation in Robeson County, North Carolina. Previously, Thomas (1989) observed that following nasal consonants may be blocking /o/ fronting in Wilmington, North Carolina. The present study examines this hypothesis in more depth in nearby Robeson County. Nine speakers were selected from the Sociolinguistic Archive and Analysis Project (Kendall, 2010). Nucleus and glide measurements were taken for each speaker's /o/ tokens, pre-lateral /o/ tokens, and pre-nasal /o/ tokens. Values were then Lobanov-normalized. Acoustic analysis of individuals speakers' vowel spaces suggests that when /o/ fronts, pre-nasal /o/ remains back along with pre-lateral /o/. While white speakers' pre-nasal /o/ patterns closely with their pre-lateral /o/, Lumbee speakers' pre-nasal /o/ tends to glide in a different direction in what could be considered a three-way allophonic split in the /o/ vowel class. The results of this study indicate that both following lateral consonants and following nasal consonants block /o/ fronting, though the phonological mechanism underlying pre-nasal /o/ backing is in need of further investigation.

Contact-Induced Changes in the Argument Structure of Middle English Verbs on the Model of Old French

This paper investigates contact-induced changes in the argument structure of Middle English verbs on the model of Old French. 1 We study two issues: i) to what extent did the English system retain and integrate the argument structure of verbs copied from French? ii) did the argument structure of these copied verbs influence the argument structure of native verbs? Our study is based on empirical evidence from Middle English corpora as well as a full text analysis of the Ayenbite of Inwyt and focusses on a number of verbs governing a dative in French. In the first part of the paper we define the contact situation and relate it to Johanson’s (2002) model of code copying. In the second part we comment on Allen’s (1995) study of please and some other psych verbs and corroborate her assumptions that i) semantic similarity triggered change within the set of these verbs, and ii) this change has reflexes in the syntactic realisation of the dative argument as a prepositional phrase. We propose a method to identify contact-induced change beyond the verb class originally affected. More explicitly, based on further empirical evidence, we show that the argument structure of the native verb give, a transfer of possession verb, was also affected by these changes and that these effects are stronger in texts that are directly influenced by French.

Home-comers as a source of language contact: Return Azorean emigrants’ English code-switching practices

AbstractThe aim of this paper is two-fold: first, it seeks to highlight the potential ofreturnemigrants — orhome-comers— to introduce lexical change in their first language (L1). Second, it represents a contribution to Lusophone linguistics and Romance linguistics more broadly in examining speech performance data from home-comers of an under-researched Portuguese variety, a dialect of Azorean Portuguese. Drawing on Backus’s notion ofentrenchment, I first present home-comers as a possible source of language change due to their contact with and potential use of L2 lexical items encountered abroad, and I highlight the Azores as an important yet overlooked site for language contact and change. In analyzing spontaneous oral narratives of emigration collected in the Azores, I demonstrate how home-comers’ ideological attitudes and linguistic resources serve as the ground on which linguistic changes occur. After examining the import of performance data on the individual level, I consider the status of a particular lexical category of code-switches — English discourse markers (i.e. ‘so’ and ‘you know’) — in Romance and their potential to become lexicalized and regarded as Portuguese in this particular contact situation.

Likein English andcomo, como que, andlikein Spanish in the speech of Southern Arizona bilinguals

Aims and Objectives/Purpose/Research Questions:This study analyzes the use of like in English and como, como que, and like in Spanish in the speech of bilinguals from Southern Arizona to assess the possible influence of like in English on its equivalents in Spanish in a language contact situation in which English is the majority language.Design/Methodology/Approach:Drawing on a discourse-pragmatic variationist approach, this study analyzes the use of like in English and its Spanish equivalents in recorded conversations between nine pairs of young Spanish-English bilingual friends from Southern Arizona.Data and Analysis:3389 tokens of like in English and its Spanish equivalents from 18 hours of recorded conversations (9 hours in each language) were analyzed quantitatively. The analysis assesses the relative frequencies of these variants and their syntactic positioning as clause-external discourse markers and clause-internal discourse particles. The independent variables of the analysis were the language of the conversation and the sex and language dominance of the participants.Findings/Conclusions:Contact with English did not appear to radically influence the use of como, como que, and like in Spanish in the speech of these bilinguals. In the speech of the same bilinguals, like in English was much more frequent and occurred in many more syntactic positions than its Spanish equivalents.Originality:This is the first study of discourse-pragmatic features in contact to analyze the use of discourse markers and discourse particles in both the donor and the recipient language in the speech of the same bilinguals.Significance/Implications:These results contribute to our knowledge of the limited interaction of linguistic repertoires in the speech of bilinguals at the discourse level even in language contact situations with a majority language. They also underline the ability of bilinguals to both understand and reproduce the subtleties of the use of these features in the two languages they speak.

Traversing language barriers

AbstractThe ‘Witoto’ people from Northwest Amazonia practised long distance drum communication, used for relaying messages among their villages. The messages were encoded on a pair of hollowed-out wooden drums, and appear to have been ‘drummed codes’, with only some iconic relation to the sound structure of the spoken language. The practice of drum communication appears to be easily diffusible in contact situations. The Caquetá-Putumayo (C-P) cultural area is a case in point, as the Witoto drums were shared with other C-P groups including the Ocaina, Nonuya, Bora, Muinane, Resígaro, and Andoque. Today, the practice of long distance drum communication among the Witoto has been long gone, with just a handful of elders who are still able to recall some of the (once extensive) drummed signal repertoire.

The effect of different occlusal contact situations on peri-implant bone stress – A contact finite element analysis of indirect axial loading

Implant restoration is one of the basic treatments in dentistry today, yet implant loss from occlusal overload is still a problem. Complex biomechanical problems such as occlusal overload are often analyzed by means of the finite element method. This numerical method makes it possible to analyze in detail the influence that different loading situations have upon implants and tissues, which is a key element in optimizing these dental procedures.This study was designed to investigate the stress distribution in peri-implant bone of a single-tooth implant crown using the finite element method. The load was applied indirectly via an occluding tooth through a three and five contact setup into the implant crown. The friction coefficient values between the crown and antagonist were varied between 0.1 and 1.0. Additionally, three crowns with cusp inclinations of 20°, 30° and 40° were modeled. Non-linear contact computations indicated that an increase in friction changed the direction and magnitude of contact forces, which also led to reduced stresses in the bone. Furthermore, the stress magnitudes were higher when cusps of a greater inclination were used. The intensity of stress alterations was strongly dependent on the distribution and number of contacts, and the contact force vector. In maximum intercuspation, a resulting axial load due to well-distributed contacts prevented high stresses in bone even with high cusp inclinations and low friction. Therefore for long-term clinical success, particular attention should be paid to occlusal adjustment so as to prevent oblique loading onto dental implant restorations.