Showing papers by "Clemson University published in 1987"

A Path Analysis of a Model of the Antecedents and Consequences of Organizational Commitment

Abstract: An attitudinal model of organizational commitment was tested using a sample of 367 managerial employees. Several aspects of the organization: perceived structure, process, and climate, as well as job satisfaction were found to be predictive of commitment. Job satisfaction and commitment were found to be equally predictive of voluntary turnover. Commitment was found to be predictive of individual motivation and objective job performance, but not of supervisors' ratings of job performance.

Constrained relations between two coordinated industrial robots for motion control

Abstract: Tasks for two coordinated industrial robots always bring the robots in contact with the same object. Physically the three form a closed kinematic chain mechanism. When the chain is in motion, the positions and orientations of the two robots must satisfy a set of holonomic equality canstraints for every time instant. To eliminate motion errors between them, we assign one of them to carry the major part of the task. Its motion is planned accordingly. The motion of the second robot is to follow that of the first robot, as specified by the re lations of the joint velocities derived from the constraint conditions. Thus if any modification of the motion is needed in real time, only the motion of the first robot is modified. The modification for the second robot is done implicitly through the constraint conditions. Specifically, when the joint displacements, velocities, and accelerations of the first robot are known for the planned or modified motion, the corre sponding variables for the second robot and the for...

A linear dynamic model for flexible robotic manipulators

Abstract: The design of lightweight links for robotic manipulators results in flexible links. Accurate control of lightweight manipulators during the large changes in configuration common to robotic tasks requires dynamic models that describe both the rigid-body motions, as well as the flexural vibrations. This paper describes a linear state-space model for a single-link flexible manipulator and compares simulation of the model to measurements made on a 4-ft-long direct-drive arm.

A continuum of disk scheduling algorithms

Abstract: A continuum of disk scheduling algorithms, V(R), having endpoints V(0) = SSTF and V(1) = SCAN, is defined. V(R) maintains a current SCAN direction (in or out) and services next the request with the smallest effective distance. The effective distance of a request that lies in the current direction is its physical distance (in cylinders) from the read/write head. The effective distance of a request in the opposite direction is its physical distance plus R x (total number of cylinders on the disk). By use of simulation methods, it is shown that this definitional continuum also provides a continuum in performance, both with respect to the mean and with respect to the standard deviation of request waiting time. For objective functions that are linear combinations of the two measures, mw + kow, intermediate points of the continuum are seen to provide performance uniformly superior to both SSTF and SCAN. A method of implementing V(R) and the results of its experimental use in a real system are presented.

Freezing the Master Production Schedule Under Rolling Planning Horizons

Abstract: The stability of the Master Production Schedule MPS is a critical issue in managing production operations with a Material Requirements Planning System. One method of achieving stability is to freeze some portion or all of the MPS. While freezing the MPS can limit the number of schedule changes, it can also produce an increase in production and inventory costs. This paper examines three decision variables in freezing the MPS: the freezing method, the freeze interval length, and the planning horizon length. Simulation experiment results are reported which suggest that freezing up to 50% of the planning horizon has a marginal effect on production and inventory cost under a wide range of operating conditions. These results also suggest that an order based freezing method produces superior results in comparison with a period based method.

Sociality and cooperativebredding of red-cockaded woodpeckers, Picoides borealis

Abstract: Thirty groups of red-cockaded woodpeckers (Picoides borealis) were studied from 1976–1982 to (1) determine the demographic structure of groups, (2) identify the role helpers play in reproductive activities, and (3) investigate the selective pressures promoting sociality and helping behavior. Groups had only 1 mated pair and 0–2 helpers. Approximately half of all groups had helpers and a given group had helpers some years but not others. Helpers, with rare exception, were males 1 or 2 years old and progeny of 1 or both members of the breeding pair. As a result of higher nestling survival, groups with helpers fledged significantly more young per year than unassisted pairs ( $$\overline X = 2.05$$ , SD=0.97,n=43 vs. $$\overline X = 1.40$$ , SD=1.01,n=50). Nesting success was also associated with size and quality of nesting period home range, but evidence suggested that the increased number of young fledged resulted directly from the action of helpers. There was a significant positive correlation between reproductive success and experience of breeding females among unassisted pairs but a significant negative correlation among pairs with helpers. In groups with experienced females, helpers were assisting both their mothers and fathers and, therefore, were related to the offspring on the average by 0.50. In groups with inexperienced females, helpers were assisting their fathers and unrelated females and were related to the offspring by 0.25. The red-cockaded woodpecker's unique habit of excavating nest and roost cavities in living pines and the extended period of time required for excavation may be an important ecological constraint that promotes the retention of helpers. Because helpers are related to the offspring they help rear, kin selection and gains in indirect fitness may provide a partial explanation of why red-cockaded woodpecker helpers help. However, the negative correlation between the efficacy of helping behavior and the helpers' relatedness to the offspring they help rear implies that helpers are least effective in producing offspring which would represent greatest gains to indirect fitness. This raises questions about the relative importance of kin selection and indirect fitness in the evolution of helping behavior among red-cockaded woodpeckers.

Identity Symbolism in Housing

Abstract: Upper-middle-class homeowners were asked to rate themselves on an extensive set of bipolar personality and identity dimensions. Photographs were taken of the interior and exterior of each homeowner...

Dual-number transformation and its applications to robotics

Abstract: In robotics, to deal with coordinate transformation in three-dimensional (3D) Cartesian space, the homogeneous transformation is usually applied. It is defined in the four-dimensional space, and its matrix multiplication performs the simultaneous rotation and translation. The homogeneous transformation, however, is a point transformation. In contrast, a line transformation can also naturally be defined in 3D Cartesian space, in which the transformed element is a line in 3D space instead of a point. In robotic kinematics and dynamics, the velocity and acceleration vectors are often the direct targets of analysis. The line transformation will have advantages over the ordinary point transformation, since the combination of the linear and angular quantities can be represented by lines in 3D space. Since a line in 3D space is determined by four independent parameters, finding an appropriate type of "number representation" which combines two real variables is the first key prerequisite. The dual number is chosen for the line representation, and lemmas and theorems indicating relavent properties of the dual number, dual vector, and dual matrix are proposed. This is followed by the transformation and manipulation for the robotic applications. The presented procedure offers an algorithm which deals with the symbolic analysis for both rotation and translation. In particular, it can effectively be used for direct determination of Jacobian matrices and their derivatives. It is shown that the proposed procedure contributes a simplified approach to the formulation of the robotic kinematics, dynamics, and control system modeling.

Confidence interval estimators for heritability for several mating and experiment designs

Abstract: Confidence interval estimators have not been described for several heritability (H) estimators relevant to recurrent family selection. Previously described H interval estimators do not apply to onefactor mating designs in split-plot in time experiment designs in one or more locations, one-factor mating designs for several experiment designs in two or more locations and years, and two-factor mating designs for several experiment designs in two or more locations or years. Our objective was to derive H interval estimators for these cases. H reduced to a function of constants and a single expected mean square ratio in every case; H=1−E(M′)/E(M″) where E(M′) is a linear function of expected mean squares and E(M″) is a single expected mean square. It was shown that F′=[M″/E(M″)]/[M′/E(M′)] has an approximate F-distribution with df″ and df′ degrees of freedom, respectively, where M′ and M″ are mean squares corresponding to E(M′) and E(M″), respectively. H is a function of F′, therefore, we used F′ to define an approximate (1−α) interval estimator for H.

Ultrastructure of spermatozoa from domesticated birds: comparative study of turkey, chicken and guinea fowl.

Abstract: Typical for non-passerine birds, the spermatozoa of the turkey, chicken and guinea fowl were vermiform with a maximum width of 0.5-0.7 micron and lengths of 90 microns for chicken sperm, and 75-80 microns for those of the turkey and guinea. An acrosome, nucleus, midpiece and flagellum could be distinguished by SEM. The acrosomal cap projected over a perforatorium surrounded by granular material. At its base, the cap encircled apical projections of the nucleus. The nucleus consisted of dense chromatin, and formed a concave implantation fossa where it joined the midpiece of the tail. For turkey and chicken spermatozoa, the neck region of the midpiece consisted of a proximal centriole and its pericentriolar processes oriented perpendicularly to an elongated distal centriole, but guinea sperm contained only a single elongated centriole and associated pericentriolar projections. The centrioles plus their projections to the implantation fossa constituted the non-striated connecting piece. The distal centriole served as the precursor of the flagellum and was longest for turkey sperm. Enveloping the distal centriole and extending to the annulus were 25-30 helically arranged mitochondria. Flagellum ultrastructure consisted of the typical 9 + 2 microtubular axonemal complex but outer dense fibers were absent. A hypertonic diluent immobilized the sperm, condensing the flagellar matrix and obliterating the radial links. Variations in ultrastructure of the above structures between sperm of the three species is discussed and compared with sperm ultrastructure from other non-passerine birds.

A fluid mechanical perspective on esophageal bolus transport

Abstract: A fluid mechanical description of peristaltic esophageal transport is presented in pedagogical form, without equations and with minimal technical jargon, using simple theoretical models of peristaltic pumping. In the most basic model, a viscous fluid is transported along a tube of circular cross-section by periodic sinusoidal contractions of the tube wall. From this model the primary mechanisms of fluid transport are discerned, and an analysis is made of the proximal leakage of bolus fluid that results from incomplete luminal contraction. A modification of the theoretical model is described next, in which a fluid layer with viscosity different than the bolus fluid is placed adjacent to the tube wall to simulate the effect of a mucous coating in esophageal transport. With this model it is discovered that, when leakage can occur, a coating of low viscosity increases the amount of leakage and reduces net transport. Finally, the theory is applied to peristaltic wave characteristics that are more representative of esophageal bolus transport; and intrabolus pressures, computed using radiographic data of bolus shapes as input, are compared with manometric measurement.

Method for continuous camlobe phasing

Abstract: A method of attaining a desired engine performance comprises the steps of changing the angular position of a variable camlobe (or cam) member relative to a fixed camlobe (or cam) member from a first angular position to a second angular position. In changing from the first to the second angular position, the variable camlobe (or cam) member moves in a predetermined direction relative to the direction of rotation of a camshaft. The predetermined direction and the magnitude of the angular movement of the variable camlobe (or cam) member is dependent at least in part upon at least one desired operating condition of the engine. The method further comprises changing the angular position of both camlobe (or cam) members relative to a reference point of a drive pulley. This change in the angular position of both of the camlobe (or cam) members relative to the reference point involves movement of the camlobes (or cams) in a direction relative to the direction of rotation of a camshaft. The direction and magnitude of this movement is based at least in part upon at least one desired operating condition of the engine.

Role of kairomones from host accessory gland secretion in host recognition by Telenomus remus and Trichogramma pretiosum, with partial characterization

Abstract: Accessory gland materials from Spodoptera frugiperda (J. E. Smith) and Heliothis zea (Boddie) (Lepidoptera: Noctuidae) contained kairomones that influenced the host recognition or acceptance behavior of Telenomus remus Nixon (Hymenoptera: Scelonidae) and Trichogramma pretiosum Riley (Hymeoptera: Trichogrammatidae), respectively. Material from S. frugiperda accessory glands stimulated ovipositor probing and drilling by female T. remus but not T. pretiosum. Accessory gland material from H. zea stimulated ovipositor probing and drilling by female T. pretiosum but not T. remus. An active material for T. remus is found in the 700 K protein fraction of accessory gland material from S. frugiperda. The oviposition behavior of the parasitoids is also discussed. RESUME Influence (et caracterisation partielle) des kairomones contenues dans les secretions des glandes annexes des hotes sur la selection de ces derniers par Telenomus remus et Trichogramma pretiosum. Cette etude a utilise une technique voisine de celle employee par Strand & Vinson (1982), pour examiner les reactions de parasitoides a des billes de verre enduites de substances, afin de determiner l'influence des secretions des glandes annexes (AGM) de Spodoptera frugiperda et Heliothis zea dans le reperage des hotes par Telenomus remus et Trichogramma pretiosum. Les femelles de T remus reagissaient plus aux billes enduites d'AGM de S. frugiperda qu'aux billes temois non enduites; celles de T. pretiosum reagissaient plus aux billes enduites d'AGM de H. zea qu'aux temoins. T remus n'a pas reagi aux billes enduites d'AGM de H. zea, ni T. pretiosum a celles enduites d'AGM de S. frugiperda. Les poids moleculaires des proteines des glandes annexes de H. zea sont 1.100 K et 50 K, et ceux de S. frugiperda de 700 K et 30 K (Strand & Vinson, 1983a). T. remus a mieux reagi aux billes enduites de la fraction 700 K de S. frugiperda qu'a celles enduites de la fraction 30 K, aux deux fractions de H. zea et aux billes temoins. Les billes enduites de la fraction 1.100 K de H. zea ont provoque aussi une reaction significative de T. remus. Les secretions des glandes annexes de S. frugiperda et de H. zea contiennent des kairomones qui interviennent dans le reperage des hotes respectifs de T remus et de T pretiosum. Mais, il semble peu probable que ces substances soient seules responsables de la reconnaissance de l'hote.

Method and apparatus for target plant foliage sensing and mapping and related materials application control

Abstract: An electronic orchard tree measuring system based on ultrasonic range transducers may be used to determine the amount and vertical distribution of sensed load centroids in vertical sectors of orchard trees. The ultrasonic transducers may be operated independently of any processor or memory which receives their distance data outputs. Displacement sensing of the apparatus relative a row of target trees may instead be used to select ultrasonic distance data at predetermined incremental distances of travel relative the trees being sensed. Thus, the most recent value of sensed data is always available as input to the processor or memory, without requiring any timing circuitry between such sensing and control circuits. The detection data may be stored in memory for subsequent processing to create a map of foliar volumes of the sensed target trees. Alternatively, the spatial characteristics of the sensed amount and vertical distribution of load centroids for a given vertical segment of target trees may be further compared spatially with determined application patterns of controllable spray nozzles to configure subsequent activation of such nozzles for optimal material application to the given vertical segment of the sensed target trees.

Vision guided robotic fabric manipulation for apparel manufacturing

Abstract: This paper details methods pertaining to the vision guided robotic control of fabric motion for performing simulated joining operations along the fabric edge. Robot motion paths are determined from visual information defining the position of the fabric edges. The function of the shape analysis and motion control algorithms is demonstrated via experimentation with an automated fabric handling system, Results of these tests show that using machine vision for planning robot motion provides an effective solution for implementing robotic fabric manipulation.

Scattering of TM excitation by coupled and partially buried cylinders at the interface between two media

Abstract: An analysis of scattering from coupled conducting cylinders near the planar interface between two semi-infinite, homogeneous halfspaces of different electromagnetic properties and from partially buried conducting cylinders is presented. The perfectly conducting cylinders of general cross sections are of infinite extent and the excitation is transverse magnetic to the cylinder axes. Coupled integral equations for the unknown current induced on the cylinders are derived and a numerical method for solving them is described. In addition, a simple technique is employed to determine the far-zone scattered field from knowledge of the cylinder current. Data displaying the distribution of the induced current and the scattered field patterns for cylinders of interest are presented and discussed.

Evaluation of calcium binding by molluscan shell organic matrix and its relevance to biomineralization

Abstract: 1. 1. EDTA used to dissolve mollusc shells associates with soluble matrix (SM) material and persists in SM preparations despite exhaustive conventional dialysis. 2. 2. EDTA-free oyster or clam SM material binds little calcium at physiological ionic strength. 3. 3. It is concluded that residual EDTA or failure to determine binding in physiological media may lead to binding artefacts and that hypotheses which rely on SM calcium binding to explain initiation of biomineral formation need to be re-evaluated. 4. 4. It is hypothesized that crystal binding, rather than calcium binding, by SM is responsible for initiation of biomineral formation.

Compliant coordination control of two moving industrial robots

Abstract: When two robots execute a coordinated motion in industrial applications such as assembly, it requires not only the specification of the desired motion of each robot's end-effector, but also the specification of the desired time histories of the force exerted by the end-effectors. The involvement of the forces leads to the need of compliance. Hence the design of a compliant control system for coordinating two industrial robots assumes the importance in many industrial applications. In this paper, a compliant control scheme and its practical implementation are presented. One robot is equipped with a wrist force/torque sensor to provide force feedback signals and to enable a fine coordinated motion control for complex assembly tasks. A control strategy is derived so that the measured interactive force/torque can be used to modify the trajectory of the robot. This control scheme can be realized in real-time by using the proposed computational structure and programming method.

Effects of sediment and contaminated sediment on structural and functional components of experimental stream ecosystems

Abstract: Three experimental stream ecosystems were used to determine the effects of sediment and contaminated sediment: one stream received 1.7 g L−1 uncontaminated sediment for 2 hr each week for 6 wk; one stream received 1.7 g L−1 contaminated sediment (50 to 1600 ppm triphenyl phosphate applied in increasing doses each week) for 2 hr each week for 6 wk; and the third stream was maintained as a control. Each stream was monitored for changes in nutrient dynamics, leaf decomposition, primary production, and invertebrate dynamics. Both sediment and sediment/triphenyl phosphate altered the drift dynamics of benthic invertebrates. Invertebrates in the sediment treatment exhibited delayed nocturnal drift, while those in the sediment/triphenyl phosphate treatment drifted immediately once a threshold of toxicity was reached. Both sediment and sediment/triphenyl phosphate decreased the percent similarity of benthic invertebrates, reduced the drift of filamentous algae, increased the production of rooted flora, and increased net nutrient retention. However, neither treatment altered leaf decomposition rates, nor affected benthic invertebrate dynamics (total number, number of species, or diversity) or insect emergence.