Evaluation of Theoretical Models to Predict the Pullout Capacity of a Vertical Anchor Embedded in Cohesionless Soil

Helical nails are a new alternative to conventional soil nails or tie-backs for stabilization of slopes, excavations, and embankments due to ease of installation, minimal site disturbance, and immediate loading capability. Pullout capacity of helical nails is a critical parameter for their design. This study investigates the pullout behaviour of helical soil nails installed in dry dense sand through a series of laboratory tests. The tests were performed on seven different types of helical nails in a displacement-controlled manner. The paper describes the test procedure, results and highlights the influence of different parameters on the pullout capacity. Results show that roughness of the nail shaft significantly influences the peak pullout capacity of helical soil nails. A linear relationship between peak pullout force and overburden pressure is observed for different types of helical soil nails, indicating that it satisfies the Mohr–Coulomb failure criteria. A helical soil nail having a double helix of unequal diameter and the same interspacing shows higher pullout capacity than a helical soil nail having a double helix of the same diameter. The position of the helix and spacing-to-diameter ratio of the soil nail with a double helix of unequal diameter plays a significant role on the peak pullout capacity.

Download Full-text

Numerical Investigation Into the Keying Process of a Plate Anchor Vertically Installed in Cohesionless Soil

Volume 9: Offshore Geotechnics; Honoring Symposium for Professor Bernard Molin on Marine and Offshore Hydrodynamics ◽

10.1115/omae2018-78617 ◽

2018 ◽

Author(s):

Nabil Al Hakeem ◽

Charles Aubeny

Keyword(s):

Peak Load ◽

Offshore Structures ◽

Cohesionless Soil ◽

Soil Conditions ◽

Embedment Depth ◽

Pullout Capacity ◽

Vertical Loading ◽

Wide Range ◽

Plate Anchor ◽

Plate Anchors

Vertically driven plate anchors offer an attractive anchoring solution for floating offshore structures, as they are both highly efficient and suitable for a wide range of soil conditions. Since they are oriented vertically after installation, keying is required to orient the anchor into the direction of applied loading. Simulation of the keying process has not been extensively investigated by previous research, especially for cohesionless soil. Reliable prediction of irrecoverable embedment loss during keying is needed, since such loss can lead to significant reduction in the uplift capacity of the plate anchors. Large deformation finite element analyses LDFE method using RITSS (Remeshing and Interpolation Technique with Small Strain) were used to simulate the keying process of strip plate anchor embedded in uniform cohesionless soil. LDFE showed that the loss in embedment depth of plate anchor during rotation is inversely proportional to the loading eccentricity e/B. It was also found that the maximum pullout capacity occurs before the end of keying process at orientations between 60° to 85° degrees for vertical loading. Also, the LDFE study showed that reduced elastic soil stiffness leading to increased levels of displacement at which the peak load is approached.

Download Full-text

Analytical Electron Microscopy of Surface-Modified Ceramics

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100118291 ◽

1985 ◽

Vol 43 ◽

pp. 276-279

Author(s):

P. S. Sklad

Keyword(s):

Electron Microscopy ◽

Analytical Electron Microscopy ◽

Theoretical Models ◽

Ceramic Materials ◽

Solute Concentration ◽

Second Phase ◽

Analytical Electron ◽

Implantation Techniques ◽

Lattice Damage ◽

Surface Modified

Over the past several years, it has become increasingly evident that materials for proposed advanced energy systems will be required to operate at high temperatures and in aggressive environments. These constraints make structural ceramics attractive materials for these systems. However it is well known that the condition of the specimen surface of ceramic materials is often critical in controlling properties such as fracture toughness, oxidation resistance, and wear resistance. Ion implantation techniques offer the potential of overcoming some of the surface related limitations.While the effects of implantation on surface sensitive properties may be measured indpendently, it is important to understand the microstructural evolution leading to these changes. Analytical electron microscopy provides a useful tool for characterizing the microstructures produced in terms of solute concentration profiles, second phase formation, lattice damage, crystallinity of the implanted layer, and annealing behavior. Such analyses allow correlations to be made with theoretical models, property measurements, and results of complimentary techniques.

Download Full-text

On the Relationship Between General Auditory Sensitivity and Speech Perception: An Examination of Pitch and Lexical Tone Perception in 4- to 6-Year-Old Children

Journal of Speech Language and Hearing Research ◽

10.1044/2019_jslhr-19-00104 ◽

2020 ◽

Vol 63 (2) ◽

pp. 487-498

Author(s):

Puisan Wong ◽

Man Wai Cheng

Keyword(s):

Speech Perception ◽

Theoretical Models ◽

Developmental Trajectory ◽

Auditory Sensitivity ◽

Pitch Discrimination ◽

Lexical Tone ◽

Perceptual Training ◽

Lexical Tones ◽

Tone Perception ◽

Tone Discrimination

Purpose Theoretical models and substantial research have proposed that general auditory sensitivity is a developmental foundation for speech perception and language acquisition. Nonetheless, controversies exist about the effectiveness of general auditory training in improving speech and language skills. This research investigated the relationships among general auditory sensitivity, phonemic speech perception, and word-level speech perception via the examination of pitch and lexical tone perception in children. Method Forty-eight typically developing 4- to 6-year-old Cantonese-speaking children were tested on the discrimination of the pitch patterns of lexical tones in synthetic stimuli, discrimination of naturally produced lexical tones, and identification of lexical tone in familiar words. Results The findings revealed that accurate lexical tone discrimination and identification did not necessarily entail the accurate discrimination of nonlinguistic stimuli that followed the pitch levels and pitch shapes of lexical tones. Although pitch discrimination and tone discrimination abilities were strongly correlated, accuracy in pitch discrimination was lower than that in tone discrimination, and nonspeech pitch discrimination ability did not precede linguistic tone discrimination in the developmental trajectory. Conclusions Contradicting the theoretical models, the findings of this study suggest that general auditory sensitivity and speech perception may not be causally or hierarchically related. The finding that accuracy in pitch discrimination is lower than that in tone discrimination suggests that comparable nonlinguistic auditory perceptual ability may not be necessary for accurate speech perception and language learning. The results cast doubt on the use of nonlinguistic auditory perceptual training to improve children's speech, language, and literacy abilities.

Download Full-text

Positive Arousal Enhances the Consolidation of Item Memory

Swiss Journal of Psychology ◽

10.1024/1421-0185/a000151 ◽

2015 ◽

Vol 74 (2) ◽

pp. 91-104 ◽

Cited By ~ 1

Author(s):

Bo Wang

Keyword(s):

Episodic Memory ◽

Memory Consolidation ◽

Source Memory ◽

Emotional Arousal ◽

Theoretical Models ◽

Memory Test ◽

Learning Phase ◽

Item Memory ◽

Memory Tests ◽

Immediate Memory

Emotional arousal induced after learning has been shown to modulate memory consolidation. However, it is unclear whether the effect of postlearning arousal can extend to different aspects of memory. This study examined the effect of postlearning positive arousal on both item memory and source memory. Participants learned a list of neutral words and took an immediate memory test. Then they watched a positive or a neutral videoclip and took delayed memory tests after either 25 minutes or 1 week had elapsed after the learning phase. In both delay conditions, positive arousal enhanced consolidation of item memory as measured by overall recognition. Furthermore, positive arousal enhanced consolidation of familiarity but not recollection. However, positive arousal appeared to have no effect on consolidation of source memory. These findings have implications for building theoretical models of the effect of emotional arousal on consolidation of episodic memory and for applying postlearning emotional arousal as a technique of memory intervention.

Download Full-text

The Role of Distress Disclosure Tendencies in the Experience and Expression of Laboratory-Induced Sadness

Journal of Individual Differences ◽

10.1027/1614-0001/a000222 ◽

2017 ◽

Vol 38 (1) ◽

pp. 55-62 ◽

Cited By ~ 1

Author(s):

Jeffrey H. Kahn ◽

Daniel W. Cox ◽

A. Myfanwy Bakker ◽

Julia I. O’Loughlin ◽

Agnieszka M. Kotlarczyk

Keyword(s):

Individual Differences ◽

Emotional Reactivity ◽

Subjective Experience ◽

Negative Emotion ◽

Theoretical Models ◽

Laboratory Research ◽

Emotion Words ◽

Distress Disclosure ◽

Computerized Text Analysis

Abstract. The benefits of talking with others about unpleasant emotions have been thoroughly investigated, but individual differences in distress disclosure tendencies have not been adequately integrated within theoretical models of emotion. The purpose of this laboratory research was to determine whether distress disclosure tendencies stem from differences in emotional reactivity or differences in emotion regulation. After completing measures of distress disclosure tendencies, social desirability, and positive and negative affect, 84 participants (74% women) were video recorded while viewing a sadness-inducing film clip. Participants completed post-film measures of affect and were then interviewed about their reactions to the film; these interviews were audio recorded for later coding and computerized text analysis. Distress disclosure tendencies were not predictive of the subjective experience of emotion, but they were positively related to facial expressions of sadness and happiness. Distress disclosure tendencies also predicted judges’ ratings of the verbal disclosure of emotion during the interview, but self-reported disclosure and use of positive and negative emotion words were not associated with distress disclosure tendencies. The authors present implications of this research for integrating individual differences in distress disclosure with models of emotion.

Download Full-text

Convergent and Predictive Validity of Implicit and Explicit Anxiety Measures as a Function of Specificity Similarity and Content Similarity

European Journal of Psychological Assessment ◽

10.1027/1015-5759.24.4.254 ◽

2008 ◽

Vol 24 (4) ◽

pp. 254-262 ◽

Cited By ~ 15

Author(s):

Tobias Gschwendner ◽

Wilhelm Hofmann ◽

Manfred Schmitt

Keyword(s):

Implicit Association Test ◽

Theoretical Models ◽

Implicit Measures ◽

Speech Anxiety ◽

Behavioral Indicators ◽

General Anxiety ◽

Anxious Behavior ◽

Content Similarity ◽

Implicit And Explicit ◽

Validation Strategy

In the present study we applied a validation strategy for implicit measures like the IAT, which complements multitrait-multimethod (MTMM) analyses. As the measurement method (implicit vs. explicit) and underlying representation format (associative vs. propositional) are often confounded, the validation of implicit measures has to go beyond MTMM analysis and requires substantive theoretical models. In the present study (N = 133), we employed such a model ( Hofmann, Gschwendner, Nosek, & Schmitt, 2005 ) and investigated two moderator constructs in the realm of anxiety: specificity similarity and content similarity. In the first session, different general and specific anxiety measures were administered, among them an Implicit Association Test (IAT) general anxiety, an IAT-spider anxiety, and an IAT that assesses speech anxiety. In the second session, participants had to deliver a speech and behavioral indicators of speech anxiety were measured. Results showed that (a) implicit and explicit anxiety measures correlated significantly only on the same specification level and if they measured the same content, and (b) specific anxiety measures best predicted concrete anxious behavior. These results are discussed regarding the validation of implicit measures.

Download Full-text

Does CBT for Psychosis Have an Impact on Delusions by Improving Reasoning Biases and Negative Self-Schemas?

Zeitschrift für Psychologie ◽

10.1027/2151-2604/a000335 ◽

2018 ◽

Vol 226 (3) ◽

pp. 152-163 ◽

Cited By ~ 2

Author(s):

Stephanie Mehl ◽

Björn Schlier ◽

Tania M. Lincoln

Keyword(s):

Behavioral Therapy ◽

Theoretical Models ◽

Self Esteem ◽

Secondary Outcome ◽

Intervention Effect ◽

Produce Change ◽

Attribution Biases ◽

Carry Over ◽

Implicit And Explicit ◽

Reasoning Biases

Abstract. Cognitive-behavioral therapy for psychosis (CBTp) builds on theoretical models that postulate reasoning biases and negative self-schemas to be involved in the formation and maintenance of delusions. However, it is unclear whether CBTp induces change in delusions by improving these proposed causal mechanisms. This study reports on a mediation analysis of a CBTp effectiveness trial in which delusions were a secondary outcome. Patients with psychosis were randomized to individualized CBTp (n = 36) or a waiting list condition (WL; n = 34). Reasoning biases (jumping to conclusions, theory of mind, attribution biases) and self-schemas (implicit and explicit self-esteem; self-schemas related to different domains) were assessed pre- and post-therapy/WL. The results reveal an intervention effect on two of four measures of delusions and on implicit self-esteem. Nevertheless, the intervention effect on delusions was not mediated by implicit self-esteem. Changes in explicit self-schemas and reasoning biases did also not mediate the intervention effects on delusions. More focused interventions may be required to produce change in reasoning and self-schemas that have the potential to carry over to delusions.

Download Full-text