Jackknifing of Tractor-Semitrailer Trucks—Detection and Corrective Action

1974 ◽  
Vol 96 (2) ◽  
pp. 244-252 ◽  
Author(s):  
E. A. Susemihl ◽  
A. I. Krauter
Keyword(s):  
Corrective Action ◽  
Slip Angle ◽  
Side Force ◽  
Local Linearization ◽  
Adequate Definition ◽  
Quantitative Manner ◽  
Definition Of ◽  
Real Vehicle

This paper is concerned with the detection of an incipient tractor jackknife of a tractor-semitrailer truck and with corrective action which can be taken after the onset of jackknifing has been sensed. An approach termed local linearization is used to define tractor jackknifing in a quantitative manner. Local linearization is then used to evaluate a second approach, termed side force-slip angle combination. This side force-slip angle combination is employed to study three forms of automatic corrective action that involve braking of the vehicle. The results obtained indicate that local linearization provides an adequate definition of the onset of jackknifing. The results also indicate that the side force-slip angle combination is useful in sensing the onset of a tractor kackknife. Through the use of approximations, the side force-slip angle combination can be implemented in a real vehicle—this implementation is found to require only simple measurements. The results of the corrective action study indicate that a certain anti-skid braking procedure may be effective in the prevention of an incipient jackknife.

Lateral Tire Forces on Wet Roads

1977 ◽  
Vol 5 (2) ◽  
pp. 75-82 ◽  
Author(s):  
A. Schallamach
Keyword(s):  
Normal Load ◽  
The Self ◽  
Experimental Results ◽  
Slip Angle ◽  
Tire Model ◽  
Side Force ◽  
Tire Forces

Abstract Expressions are derived for side force and self-aligning torque of a simple tire model on wet roads with velocity-dependent friction. The results agree qualitatively with experimental results at moderate speeds. In particular, the theory correctly predicts that the self-aligning torque can become negative under easily realizable circumstances. The slip angle at which the torque reverses sign should increase with the normal load.

Theoretical Tire Model Considering Two-Dimensional Contact Patch for Force and Moment

2021 ◽  
Author(s):  
Y. Nakajima ◽  
S. Hidano
Keyword(s):  
Finite Element Method ◽  
Shear Force ◽  
The Self ◽  
Slip Angle ◽  
Force Distribution ◽  
Two Dimensional ◽  
Tire Model ◽  
Side Force ◽  
Contact Patch ◽  
Proposed Model

ABSTRACT The new theoretical tire model for force and moment has been developed by considering a two-dimensional contact patch of a tire with rib pattern. The force and moment are compared with the calculation by finite element method (FEM). The side force predicted by the theoretical tire model is somewhat undervalued as compared with the FEM calculation, while the self-aligning torque predicted by the theoretical tire model agrees well with the FEM calculation. The shear force distribution in a two-dimensional contact patch under slip angle predicted by the proposed model qualitatively agrees with the FEM calculation. Furthermore, the distribution of the adhesion region and sliding region in a two-dimensional contact patch predicted by the theoretical tire model qualitatively agrees with the FEM calculation.

scholarly journals When is a Learning Object not an Object: A first step towards a theory of learning objects

2002 ◽  
Vol 3 (2) ◽  
Author(s):  
Mike Sosteric ◽  
Susan Hesemeier
Keyword(s):  
Economies Of Scale ◽  
Learning Objects ◽  
Short Term ◽  
Object A ◽  
Smart Learning ◽  
Smart Learning Environments ◽  
Adequate Definition ◽  
Definition Of ◽  
Conceptual Confusion

<p> For some, “learning objects" are the “next big thing” in distance education promising smart learning environments, fantastic economies of scale, and the power to tap into expanding educational markets. While learning objects may be revolutionary in the long term, in the short term, definitional problems and conceptual confusion undermine our ability to understand and critically evaluate the emerging field. This article is an attempt to provide an adequate definition of learning objects by (a) jettisoning useless theoretical links hitherto invoked to theorize learning objects, and (b) reducing the definition of learning objects to the bare essentials. The article closes with suggestions for further research and further refinement of the definition of learning objects. </P>

scholarly journals On the notion of visual illusions

Psihologija ◽  
2014 ◽  
Vol 47 (3) ◽  
pp. 359-367 ◽  
Author(s):  
Dejan Todorovic
Keyword(s):  
Visual Illusions ◽  
Adequate Definition ◽  
Definition Of

The usual definitions of illusions, as incorrect perceptions or cases of discrepancies between reality and our perception of reality, have been criticized as inadequate. The reason is that it is not clear how to apply this notion in a number of interesting cases. This paper is an attempt to provide an adequate definition of illusions, appropriate for many classical phenomena usually referred to as illusions.

scholarly journals The Use and Meaning of the Past in Plato

Plato Journal ◽  
2021 ◽  
Vol 21 ◽  
pp. 43-58
Author(s):  
Maurizio Migliori
Keyword(s):  
Historical Analysis ◽  
The Past ◽  
Philosophical Writing ◽  
Adequate Definition ◽  
Definition Of ◽  
The Relationship

This essay is based on two premises. The first concerns the vision of writing proposed by Plato in Phaedrus and especially the conception of philosophical writing as a maieutic game. The structurally polyvalent way in which Plato approaches philosophical issues also emerges in the dialogues. The second concerns the birth and the development of historical analysis in parallel with the birth of philosophy. On this basis the text investigates a series of data about the relationship between Plato and "the facts". 1) If we compare the Apology of Socrates with other sources, we discover a series of important “games” that Plato performs to achieve the results he proposes. 2) The famous passage of Phaedo 96A-102A, which concludes with the Ideas and with a reference to the Principles, expresses definite judgments on the Presocratics. 3) In his works Plato attributes to the sophists some merits, even if the outcome of their contri-bution is overall negative. 4) However, in the fourth complicated diairesis of the Sophist, there is a "sophist of noble stock", an educator who can only be Socrates. 5) Plato in the Sophist shows the weakness of the Gigantomachy, and proposes an adequate definition of the beings: the power of undergoing or acting. This reveals, before the Philebus and the Timaeus, the dynamic and dialectical nature of his philosophy In summary, a multifocal vision emerges, adapted to an intrinsically complex reality.

scholarly journals Lumbar Intervertebral Motion in Healthy Male Participants: Protocol for a Motion Analysis During Flexion and Extension Cinematographic Recordings

10.2196/14741 ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. e14741
Author(s):  
Inge J M H Caelers ◽  
Toon F M Boselie ◽  
Kim Rijkers ◽  
Wouter L W Van Hemert ◽  
Rob A De Bie ◽  
...  
Keyword(s):  
Lumbar Spine ◽  
Health Care Professionals ◽  
Healthy Male ◽  
Motion Patterns ◽  
Maximum Flexion ◽  
Adequate Definition ◽  
Physiological Motion ◽  
Definition Of ◽  
Medical Research Ethics ◽  
Flexion And Extension

Background Physiological motion of the lumbar spine is a subject of interest for musculoskeletal health care professionals, as abnormal motion is believed to be related to lumbar conditions and complaints. Many researchers have described ranges of motion for the lumbar spine, but only a few have mentioned specific motion patterns of each individual segment during flexion and extension. These motion patterns mostly comprise the sequence of segmental initiation in sagittal rotation. However, an adequate definition of physiological motion of the lumbar spine is still lacking. The reason for this is the reporting of different ranges of motion and sequences of segmental initiation in previous studies. Furthermore, due to insufficient fields of view, none of these papers have reported on maximum flexion and extension motion patterns of L1 to S1. In the lower cervical spine, a consistent pattern of segmental contributions was recently described. In order to understand physiological motion of the lumbar spine, it is necessary to systematically study motion patterns, including the sequence of segmental contribution, of vertebrae L1 to S1 in healthy individuals during maximum flexion and extension. Objective This study aims to define the lumbar spines’ physiological motion pattern of vertebrae L1, L2, L3, L4, L5, and S1 by determining the sequence of segmental contribution and the sequence of segmental initiation of motion in sagittal rotation of each vertebra during maximum flexion and extension. The secondary endpoint will be exploring the possibility of analyzing the intervertebral horizontal and vertical translation of each vertebra during maximum flexion and extension. Methods Cinematographic recordings will be performed on 11 healthy male participants, aged 18-25 years, without a history of spine problems. Cinematographic flexion and extension recordings will be made at two time points with a minimum 2-week interval in between. Results The study has been approved by the local institutional medical ethical committee (Medical Research Ethics Committee of Zuyderland and Zuyd University of Applied Sciences) on September 24, 2018. Inclusion of participants will be completed in 2020. Conclusions If successful, these physiological motion patterns can be compared with motion patterns of patients with lumbar conditions before or after surgery. Ultimately, researchers may be able to determine differences in biomechanics that can potentially be linked to physical complaints like low back pain. Trial Registration ClinicalTrials.gov NCT03737227; https://clinicaltrials.gov/ct2/show/NCT03737227 International Registered Report Identifier (IRRID) DERR1-10.2196/14741

scholarly journals Multivocity in Topics 1.15

2016 ◽  
Vol 7 (1) ◽  
pp. 69-86
Author(s):  
Mikołaj Domaradzki
Keyword(s):  
Different Types ◽  
Adequate Definition ◽  
The Many ◽  
Definition Of

This paper discusses Aristotle’s account of multivocity (πολλαχῶς/ πλεοναχῶς λέγεται) as expounded in Topics 1.15. This article argues that an inquiry into how many ways (ποσαχῶς) something is said becomes for Aristotle a tool of dialectical examination that he employs throughout his entire philosophical career: investigating the many/multiple ways (πολλαχῶς/πλεοναχῶς) something is said allows one to recognize the ambiguity of the term in question and, consequently, to construct an adequate definition of its referent. The present study reconstructs the various strategies for detecting ambiguity and discusses its different types. Subsequently, the paper accounts for why Aristotle moves so easily from words and their meanings to things and their essences. Finally, the article presents an analysis of the connection between the many ways something is said and the various categories it is predicated in. The considerations are supported by a new translation of Topics 1.15.

Community Pharmacists' Knowledge of Antioxidant Vitamins

1996 ◽  
Vol 12 (4) ◽  
pp. 149-154 ◽  
Author(s):  
Debra M Offricht ◽  
Margaret Malone
Keyword(s):  
Current Literature ◽  
Demographic Data ◽  
Community Pharmacists ◽  
Primary Objective ◽  
Antioxidant Vitamins ◽  
Telephone Directory ◽  
Inadequate Information ◽  
Adequate Definition ◽  
Antioxidant Supplements ◽  
Definition Of

Objective: The current interest in antioxidant vitamins has led consumers to seek advice from community pharmacists. The primary objective of this study was to evaluate community pharmacists' knowledge of antioxidant vitamins. Design: An interviewer-based questionnaire was developed to represent the questions most frequently asked by consumers in community pharmacies about antioxidant vitamins. Setting: Pharmacies in the Tri-cities area (Albany, Schenectady, and Troy, NY) were identified from the Yellow Pages of the Albany, NY telephone directory, and each was visited by the interviewer (DMO). Main Outcome Measures: Questions were divided into the demographic data and practice setting of the participant; the antioxidant vitamins, knowledge of supplements and foods containing antioxidants, dosage recommendations, and toxicities; and therapeutic claims attributed to their use. Results: Of 75 pharmacists approached, 70 agreed to participate in the study. The number of questions per week received from customers regarding antioxidant vitamins was estimated to be between 0 and 25. All pharmacists had heard of the terms “free radical” and “antioxidant,” but few were able to provide an adequate definition of either term. The majority of pharmacists knew which vitamins are considered to be antioxidants, but were unfamiliar with appropriate dosage recommendations. In keeping with current literature recommendations, the use of antioxidant supplements was generally not advocated. Conclusions: In this study, pharmacists provided inadequate information regarding antioxidant vitamins. Because antioxidants are rarely indicated according to the current literature, pharmacists have a responsibility to base their recommendations to customers on substantiated data.

A Laboratory Method to Comprehensively Evaluate Abrasion, Traction and Rolling Resistance of Tire Tread Compounds

2007 ◽  
Vol 80 (4) ◽  
pp. 580-607 ◽  
Author(s):  
M. Heinz ◽  
K. A. Grosch
Keyword(s):  
Friction Coefficient ◽  
Laboratory Test ◽  
Rolling Resistance ◽  
Limited Range ◽  
Slip Angle ◽  
Testing Conditions ◽  
Side Force ◽  
The Road ◽  
Wide Range ◽  
On The Road

Abstract A laboratory test method has been developed which allows the evaluation of diverse properties of tire tread compounds on the same sample. The laboratory test instrument consists of a rotating abrasive disk against which a rubber sample wheel runs under a given load, slip angle and speed. All three force components acting on the wheel during the tests are recorded. By changing the variable values over a wide range practically all severities encountered in tire wear are covered. The well-known fact that compound ratings depend on the road testing conditions is verified. Most compounds are only significantly distinguishable against a control over a limited range of testing conditions. Using a road test simulation computer program based on the laboratory data shows that not only ratings correspond to practical experience but also calculated absolute tire life times do. Tests on surfaces of different coarseness and sharpness indicate that sharp coarse surfaces give the best results with road tests, which of necessity are mostly carried out on public roads of differing constitution. The abrasive surface can be wetted with water at different temperatures and hence either the friction force at a locked wheel or the side force at a slipping wheel can be measured over a wide range of temperatures and speeds. At small slip angles the side force is dominated by dynamic cornering stiffness of the compound, at large slip angles by the friction coefficient. In this case, too, good correlations to road experience exist over a limited range of testing conditions. Low water temperatures and low slip speed settings in the laboratory produce side force ratings, which correlate closely with ABS braking on the road High and higher slip speeds give ratings in close agreement with locked wheel braking on the road. A heatable/coolable disk enables traction measurements on ice and newly abrasion measurements on surfaces at elevated surface temperature. Ice surface temperatures between −5 °C and −25 °C are possible. Friction measurements show that the difference in compound rating between summer and winter compounds is maintained over the whole temperature range. New investigations show not only a differentiation between different winter tire treads qualities but also an excellent correlation between tire and laboratory results. As a new topic side force measurements on dry surfaces highlight the correlation to dry handling of tires. The tire tread compound contributes to this performance through its shear stiffness and its friction coefficient. The shear stiffness contributes to the response of the tire in directional changes. The friction coefficient determines the maximum force, which can be transmitted. A simple operation possibility for evaluation of determined side forces is demonstrated. In addition to antecedent investigations the rolling resistance of the rubber wheel can be measured over a range of loads and speeds with the slip angle set at zero. Again for these new results good correlations are achieved with practical experience. In particular, the dependence of the rolling resistance on the velocity and loads are pointed out. Ultimately a good correlation between tire test and laboratory test results was demonstrated.

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