Force Variance Research Articles

Calculation method for deformations of stand and rolls to obtain products with small dimension of tolerances

The article presents calculation method for the dimensions of the stand and of the diameter of rolls to obtain products with small dimension of tolerances. Calculations have shown the existence of optimum diameters of the rolls. The calculated results of the effects of process force variance on the deformation of the stand are also given. It was shown that simpler and economical models can be often used for the practical needs. Reasons for making complicated and expensive models are discussed.

Influence of Transverse Shear on Stochastic Instability of the Elastic Beam

In the case when Kirchhoff–Love hypotheses do not give satisfactory results, we have to take the rotatory inertia and transverse shear into account. This paper studies the elastic beam subjected to stochastic axial load, when transverse shear is taken into account. By using the direct Liapunov method, the bounds of the almost sure instability of beams as the function of the damping coefficient, variance of the stochastic force, geometric parameters, mode number, section shape factor and intensity of the deterministic component of axial loading, are obtained. Calculations are performed for the Gaussian process with zero mean and variance σ2, as well as for the harmonic process with amplitude A.

The Role of Genetics and Environment in Lifting Force and Isometric Trunk Extensor Endurance

Our understanding of what different back performance tests are measuring is limited. The purpose of this study was to investigate the relative contributions of genetics and unique and common environmental factors for 3 tests of back muscle performance in a classic twin analysis. The subjects were a population-based sample of 122 monozygotic and 131 dizygotic male twin pairs aged 35 to 69 years (mean=49.9, SD=7.7). Variance component analysis was applied to estimate genetic and environmental influences on isokinetic and psychophysical lifting and isometric trunk extensor endurance test performance. The Cholesky decomposition genetic factor model was used to estimate genetic and environmental correlations of these variables. Path analysis was applied to study determinants of isokinetic and psychophysical lifting and isometric trunk extensor endurance test performance. Genetic effects accounted for 60%, 33%, and 5% of the total variance of isokinetic and psychophysical lifting forces and isometric trunk extensor endurance, respectively, and unique environmental factors accounted for 35%, 49%, and 61% of the variance. Genetics had a dominant role in isokinetic lifting and unique environmental factors in isometric trunk extensor endurance. The relatively high role of genetics in lifting force suggests the potential to increase and sustain changes in back muscle force in the general population may be particularly challenging.

Finger interaction during accurate multi-finger force production tasks in young and elderly persons

We addressed a hypothesis that changes in indices of finger interaction during maximal force production (MVC) tasks are accompanied by changed coordination of fingers in multi-finger accurate force production tasks. To modify relative involvement of extrinsic and intrinsic hand muscles, the subjects produced force by pressing either at their distal phalanges or at their proximal phalanges. As in earlier studies, in MVC trials, the elderly subjects showed a greater force decline when pressing at the proximal phalanges as compared to pressing at the distal phalanges. Two methods were applied to analyze finger coordination during the task of four-finger force production from zero to 30% of MVC over 5 s, at the level of finger forces (performance variables) and at the level of modes (control variables). Our previous observations of higher indices of variability during the ramp task in elderly subjects have been generalized to both sites of force application. An index of finger force covariation (the difference between the variance of the total force and the sum of the variances of individual finger forces) revealed small age related differences, which did not depend on the site of the force application. In contrast, analysis of covariation of force modes within the uncontrolled manifold (UCM) hypothesis showed much better stabilization of the time profile of the total force by young subjects. The UCM hypothesis was also used to test stabilization of the pronation/supination moment during the ramp task. Young subjects showed better moment stabilization than elderly. Age related differences in both force- and moment-stabilization effects were particularly strong during force application at the proximal phalanges. We conclude that the drop in MVC is accompanied in elderly subjects with worse coordination of control signals to fingers in multi-finger tasks. The UCM analysis was more powerful as compared to analysis of force variance profiles in revealing significant differences between the groups. This general result underscores the importance of efforts to analyze motor coordination using control rather than performance variables.

Performance Evaluation of a Wearable Vibrotactile Glove for Telemanipulation

This presentation discusses two controlled experiments conducted to measure objectively the ability of a vibrotactile glove to convey discriminable finger touch forces to an operator performing telemanipulation tasks. In the first experiment, the user performs a pick-and-place task with objects of known relative weight under the added constraint that he/she maintains grip forces within a controlled force range. Using measures such as the mean and variance of grip forces, this work demonstrates that proportional touch feedback allows the user to better regulate his/her grip forces with proportional touch feedback over no-feedback or binary touch feedback. In the second experiment, which is a reverse of the first experiment, the user sorts objects by relative weight. This second experiment shows that the vibrotactile glove allows the user to discriminate relative object features, such as weight.

Changes in finger coordination and responses to single pulse TMS of motor cortex during practice of a multifinger force production task.

We investigated the changes in finger coordination and in finger force responses to transcranial magnetic stimulation (TMS) applied over the motor cortex associated with a single practice session of an accurate ramp force production task. Subjects pressed with their index, middle and ring fingers onto three force transducers fixed to a rigid platform that was balanced on a narrow pivot under the middle finger. The task was to produce a smoothly increasing ramp of total force from 0 to 25 N over 4 s following a visual target. Subjects performed three brief series of trials without TMS (12 trials each) in the beginning, in the middle, and in the end of the experiment. The main part of the experiment involved 173 trials, and in each of them at random times in the ramp a suprathreshold TMS pulse was applied over the hand area of the contralateral motor cortex in order to evoke a twitch in the finger flexor muscles. At the end of the experiment the subjects also performed 12 constant force production trials, and TMS was unexpectedly applied in each trial. During the ramp force trials the amplitude of the response to TMS was largely independent of the force exerted at the time of stimulation, whereas in static holding trials the amplitude of the response increased with higher levels of background contraction. Over time subjects improved their overall tracking performance: the variance of the force trajectory (VarF(TOT)), as computed over sets of unperturbed trials, declined by 60% after the first 100 trials, but there was little additional improvement after the second 100 trials. Variance in the force finger space related to the total moment with respect to the pivot also showed a decline during the first half of practice and minimal further changes during the second half. In contrast, finger force variance that did not affect either total force or total moment showed no changes after the first 100 trials and a decline during the second 100 trials. This variance component quantified per finger was significantly larger than those related to the total force and total moment. The mean size of the TMS-induced phasic force increment decreased by 12% over the course of the 200 trials. The forces evoked in the index and ring fingers gradually became more equal, reducing the total moment with respect to the pivot and improving balance. We speculate that development of a relatively low twitch force with low total moment on the pivot made it easier for subjects to continue tracking after the TMS pulse. Such changes could well be correlated with the degree of corticospinal involvement in the task. The results suggest task specific, practice-related plastic changes in neural structures involved in the responses to TMS.

Voluntary Activation and Decreased Force Production of the Quadriceps Femoris Muscle After Total Knee Arthroplasty

Quadriceps femoris muscle weakness as manifested by a decrease in force-generating capability is a persistent problem after total knee arthroplasty (TKA). The authors hypothesized that (1) patients with a TKA would have decreased quadriceps femoris muscle performance (weakness) and impaired volitional activation when compared with a group of older adults without knee pathology, (2) pain and age would account for a large portion of the variability in volitional activation after surgery, and (3) volitional activation in the TKA group would account for a large portion of the variability in force production. Comparison subjects were 52 volunteers (mean age=72.2 years, SD=5.34, range=64-85). The TKA group comprised 52 patients (mean age=64.9 years, SD=7.72, range=49-78) with a diagnosis of osteoarthritis who had undergone a tricompartmental, cemented TKA. Knee extension force was measured using a burst superimposition technique, where a supramaximal burst of electrical stimulation was superimposed on a maximal voluntary isometric contraction (MVIC). The amount of failure of volitional activation is determined by the amount of electrical augmentation of force beyond a person's MVIC at the instant of the application of the electrical burst. The average normalized knee extension force of the TKA group was 64% lower than that of the comparison group. The average volitional activation deficit in the TKA group (26%) was 4 times as great as the comparison group's deficit (6%). Age did not correlate with quadriceps femoris muscle activation, and knee pain explained only a small portion of the variance in knee extension force (r2=.17). Volitional activation was highly correlated with knee extension force production (r2=.65). Considerable quadriceps femoris muscle inhibition after surgery has several implications for recovery. Rehabilitation programs that focus on volitional exercise alone are unlikely to overcome this pronounced failure of activation. Early interventions focused at improving quadriceps femoris muscle voluntary activation may improve efforts to restore muscle force.

Approaches to analysis of handwriting as a task of coordinating a redundant motor system

We consider problems of motor redundancy associated with handwriting using the framework of the uncontrolled manifold (UCM) hypothesis. Recent studies of finger coordination during force production tasks have demonstrated that the UCM-hypothesis provides a fruitful framework for analysis of multi-finger actions. In particular, it has been shown that during relatively fast force changes, finger force variance across trials is structured such that a time pattern of total moment produced by the fingers with respect to a point between the two most lateral fingers involved in the task is stabilized while the time pattern of total force may be destabilized. The findings of selective moment stabilization have been interpreted as being conditioned by the experience with everyday motor tasks that commonly pose more strict requirements to stabilization of total moment than to stabilization of total force. We discuss implications of these findings for certain features of handwriting seen in elderly, children, patients with neurological disorders, and forgers.

Coupled buffeting response analysis of long-span bridges by the CQC approach

Based on the modal coordinates of the structure, a finite-element and CQC (complete quadratic combination) method for analyzing the coupled buffeting response of long-span bridges is presented. The formulation of nodal equivalent aerodynamic buffeting forces is derived based on a reasonable assumption. The power spectral density and variance of nodal displacements and elemental internal forces of the bridge structure are computed using the finite-element method and the random vibration theory. The method presented is very efficient and can consider the arbitrary spectrum and spatial coherence of natural winds and the multimode and intermode effects on the buffeting responses of bridge structures. A coupled buffeting analysis of the Jiangyin Yangtse River Suspension Bridge with 1385 in main span is performed as an example. The results analyzed show that the multimode and intermode effects on the buffeting response of the bridge deck are quite remarkable.

Effects of age and gender on finger coordination in MVC and submaximal force-matching tasks.

The objective of the study is to examine the effects of age and gender on finger coordination. Twelve young (24 +/- 8 yr; 6 men and 6 women) and 12 elderly (75 +/- 5 yr; 6 men and 6 women) subjects performed single-finger maximal contraction [maximal voluntary contraction (MVC)], four-finger MVC, and four-finger ramp force production tasks by pressing on individual force transducers. A drop in the force of individual fingers during four-finger MVC tasks compared with single-finger MVC tasks (force deficit) was larger, whereas unintended force production by other fingers during single-finger MVC tasks (enslaving) was smaller, in elderly than in young subjects and in women than in men. Force deficit was smaller and enslaving was larger in subjects with higher peak force. During the ramp task, the difference between the variance of total force and the sum of variances of individual forces showed a logarithmic relation to the level of total force, across all subject groups. These findings suggest that indexes of finger coordination scale with force-generating capabilities across gender and age groups.

CUTTING EFFICIENCY THROUGH OPTIMISED BIT CONFIGURATION — AN EXPERIMENTAL STUDY USING A SIMULATED CONTINUOUS MINER

Mineral Resources EngineeringVol. 10, No. 04, pp. 427-434 (2001) Technical NotesNo AccessCUTTING EFFICIENCY THROUGH OPTIMISED BIT CONFIGURATION — AN EXPERIMENTAL STUDY USING A SIMULATED CONTINUOUS MINERV. B. ACHANTI and A. W. KHAIRV. B. ACHANTICap Gemini Ernst & Young, 10 Glenlake Parkway, Suite 1000, Atlanta, GA, USA Search for more papers by this author and A. W. KHAIRDepartment of Mining Engineering, West Virginia University, Morgantown, WV, USA Search for more papers by this author https://doi.org/10.1142/S0950609801000737Cited by:7 PreviousNext AboutSectionsPDF/EPUB ToolsAdd to favoritesDownload CitationsTrack CitationsRecommend to Library ShareShare onFacebookTwitterLinked InRedditEmail AbstractStudies related to cutting efficiency of a continuous miner in the past have indicated that the mining community has centered its attention on mastering two goals — minimising energy required to perform cutting operations and decreasing the amount of respirable dust generated during the cutting process. Unfortunately, these tasks have not been met successfully. There is a need to investigate bit design configuration in more depth in order to perform rock cutting efficiently. Essentially, a better understanding of the influence of several parameters, including both machine-controlled and operator-controlled, during the rock cutting process is required.In the study presented in this paper, four different bit geometry-related parameters were investigated to evaluate their effect on the cutting efficiency of a continuous miner. The parameters include: bit spacing, cutting depth, cutting drum rotational speed, and bit tip angle. The experimental study was conducted on an Automated Rotary Coal/Rock Cutting Simulator (ARCCS) in the Rock Mechanics Laboratories at the West Virginia University. An orthogonal fractional factorial experimental plan was utilised to carry out the experiments. Indiana limestone was used as the test material. The results of the study are compiled to represent a nomogram/graphical model, which is intended to assist cutting bit selection on a continuous miner. The model incorporates a normalised shear load factor, defined as a ratio of shear load component required for removing rock lands/ridges to shear strength of the rock, and specific respirable dust generated during rock cutting. Finally, the paper highlights the benefits of this model to the operators/owners of continuous miners in selecting optimum rock cutting parameters. FiguresReferencesRelatedDetailsCited By 7A Review of Selected Solutions on the Evaluation of Coal-Rock Cutting Performances of Shearer Picks under Complex Geological ConditionsLinlin Wang, Dekun Zhang, Dagang Wang and Cunao Feng2 December 2022 | Applied Sciences, Vol. 12, No. 23Comprehensive performance analysis of a shearer drum in a complicated seam based on discrete element methodLijuan Zhao, Meichen Zhang, Baisheng Shi, Xionghao Liu and Yadong Wang12 August 2021 | Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, Vol. 236, No. 5Coal fragment size model in cutting processXiaohui Liu, Songyong Liu and Ping Tang1 Mar 2015 | Powder Technology, Vol. 272Simulation and Study of Random Loads on Continuous Miner Cutting DrumXiao Huo Li, Xin Wei Yu, Xiao Hong Ma and Ying Bo Zhao1 August 2011 | Advanced Materials Research, Vol. 308-310Establishing aerosol exposure predictive models based on vibration measurementsJhy-Charm Soo, Perng-Jy Tsai, Shih-Chuan Lee, Shih-Yi Lu and Cheng-Ping Chang et al.1 Jun 2010 | Journal of Hazardous Materials, Vol. 178, No. 1-3Establishing aerosol exposure predictive models based on noise measurements—using concrete drilling as an exampleJhy-Charm Soo, Perng-Jy Tsai, Ching-Hwa Chen, Der-Jen Hsu and Yu-Tung Dai et al.1 Jan 2009 | Journal of Environmental Monitoring, Vol. 11, No. 8Analysis of force variance for a continuous miner drum using the Design of Experiments methodS. Somanchi, V. J. Kecojevic and C. J. Bise1 Jun 2006 | International Journal of Mining, Reclamation and Environment, Vol. 20, No. 2 Recommended Vol. 10, No. 04 Metrics History PDF download

Structure of motor variability in marginally redundant multifinger force production tasks.

The framework of the uncontrolled manifold hypothesis (UCM hypothesis) was applied to the analysis of the structure of finger force variability during oscillatory force production tasks. Subjects produced cycles of force with one, two (index and middle), or three (index, middle, and ring) fingers acting in parallel against force sensors mounted inside a small frame. The frame could be placed on the top of a table (stable conditions) or on a 4-mm-wide supporting surface (unstable conditions). Subjects were less variable when they used two fingers than when using one finger; adding the third finger did not change indices of variability of the performance. Components of finger force variance that did (VUN) or did not (VCOMP) change the value of a particular functional variable were computed for two control hypotheses: (1) at each time, the subjects tried to stabilize the total value of force (force-control); and (2), at each time, the subjects tried to stabilize the total moment produced with respect to an axis parallel to the hand/forearm (moment-control). Most subjects showed selective stabilization of moment and destabilization of force throughout most of the force cycle, in both stable and unstable conditions. The shapes of VUN and VCOMP suggested a possibility of selective compensation of timing errors across fingers within force cycles. One subject showed different relations between VUN and VCOMP, suggesting that these relations did in fact reflect particular central strategies of solving the tasks. The UCM method is applicable to force production tasks. It allows the comparison of control hypotheses in a quantitative way and unveils central strategies of control of redundant motor systems. Within this approach, redundancy (rather, abundance) is not a problem but an inherent part of a solution for natural motor tasks.

Influence of transverse shear on stochastic instability of viscoelastic beam

The stochastic instability problem associated with an axially loaded Timochenko beam made of viscoelastic material is formulated. The beam is treated as Voigt–Kelvin body compressed by time-dependent deterministic and stochastic forces. By using the direct Liapunov method, bounds of the almost sure instability of beams as a function of retardation time, variance of the stochastic force, mode number, section shape factor and intensity of the deterministic component of axial loading, are obtained. Calculations are performed for the Gaussian process with a zero mean and variance σ 2 as well as for harmonic process with an amplitude A.

The relationship between tenderness, proteolysis, muscle contraction and dissociation of actomyosin

The right side m. longmissius thoracis et lumborum (LTL) of 18 10-month-old male lambs was injected with the protease inhibitor E-64, and the left side was injected with isotonic saline within 30 min of stunning. Carcasses were hung during chilling by one of three methods; Achilles tendon; pubic symphysis or pubic symphysis with 2-kg weights attached to each hindleg. The LTL section was divided into three portions and aged for either 1, 3 or 7 days. The tenderness, myofibrillar fragmentation and dissociation of extracted actomyosin by pyrophosphate were determined for each portion of LTL. The protease inhibitor increased shear force values by 57%, with a decrease in shear force in the cranial-caudal direction along the LTL. Muscle from Achilles hung carcasses was the toughest. For sarcomere length hanging method had the greatest effect, with muscle from tenderstretched/weighted carcasses having the longest sarcomeres. Injection of an inhibitor caused a significant reduction in myofibrillar fragmentation ( P< 0.001) and hanging method and ageing period also significantly affected this characteristic ( P< 0.05). Osmolality of samples aged for 1 day was unaffected by any main effect. The amount of actomyosin (mg/g of muscle sample) extracted from muscles injected with the inhibitor was significantly less ( P< 0.001) and there was also a significant effect ( P< 0.05) of portion on this variable. The relationship between pyrophosphate and the percentage of myosin dissociated from the actomyosin complex was modelled using an exponential function; Y= A − B exp − kx . Analysis of A, B and k for the 69 samples fitted with an exponential function showed that there was no significant effect ( P>0.05) on A and k of any main effect or their interactions. There was, however, a significant effect ( P<0.05) of portion on B and also a significant interaction between injection and hanging method ( P<0.05). It was found that B did not explain any additional variance in shear force or myofibrillar fragmentation over the main effects and interactions previously found significant. The inhibitor E-64 was effective at preventing tenderisation indicating the role of cysteine proteases in proteolytic degradation. There was no apparent effect of dissociation on tenderness as measured in this experiment and therefore a causal relationship cannot be identified.

Analysis of Compression Force in the Hip Joint during Impulsive Exercises: A Preliminary Study for Developing Exercise Protocol for Osteoporosis.

Past intervention studies on bone remodeling for preventing osteoporosis in elderly women often lack sufficient description of the intensity of the exercise, though bone remodeling is dependent on applied force at specific sites. The effectiveness of exercise in increasing bone density cannot be defined without sufficient description of the intensity and targeted site of the exercise. We conducted kinetic and kinematic analyses of the lower extremities in order to categorize exercise in terms of compression force applied at the proximal end of the femur, to formulate guidelines for prescribing exercise to elderly women. Thirty healthy women aged 18-24 participated in the study. Joint compression force at the proximal end of the femur was measured with the aid of motion analysis devices under several conditions of impulsive loading. Joint compression force at the proximal end of the femur was estimated for twenty-two exercise regimes varying from low to high-impact exercises, including jumping off, stepping down, vertical jumping, and dropping down after heel raises. Some exercises appear to be inappropriate for exercise intervention, because the variability for these exercises is high. Most of the jumping exercises, with coefficients exceeding 0.36, were excluded from further analysis. Of the remaining exercises, four were categorized as statistically different loads, as determined by a posthoc test of one-way analysis of variance of joint compression force. These included jumping off a 10 cm platform, stepping down from a 20 cm platform with the knees in the extended position, stepping down from a 20 cm platform with the knees in a relaxed position, and heel dropping at 80 cycles per minute with the knees in a relaxed position. The joint compression forces during these exercises were 2.32 ± .81, 1.81 ± .59, 1.45 ± .59, and 1.00 ± .27 times as much as the subject's body weight, respectively.

Force production in the rugby union scrum

In this study, we examined the relationship between anthropometric, strength and power characteristics of rugby forwards, their body position when scrummaging, and their ability to apply force when scrummaging. Force applied to an instrumented scrum machine was measured for 56 players, both individually and as scrum packs. Measurements of body position for individuals were made by digitizing videotape records of the trials. Forty players subsequently had their anthropometry assessed and completed several strength and power tests. Body mass, each component of somatotype, maximal anaerobic power developed on a cycle ergometer, and isokinetic knee extension strength correlated significantly with individual scrummaging force. A regression model (P≪0.001) including body mass, mesomorphy, maximal anaerobic power and hip angle while in the scrummaging position accounted for 45% of the variance in individual scrummaging force. The packs that produced the largest scrummaging forces were, in general, characterized by a greater pack force to sum of individual force ratio than the packs producing lower forces. Our results emphasize the need for a scrum pack to develop technique and coordination as a unit to maximize scrummaging force.

Impulse and Movement Space—Time Variability

In 3 experiments, the authors examined movement space—time variability as a function of the force-time properties of the initial impulse in a movement timing task. In the range of motion and movement time task conditions, peak force, initial rate of force, and force duration were manipulated either independently or in combination across a range of parameter values. The findings showed that (a) impulse variability is predicted well by the elaboration of the isometric force variability scaling functions of L. G Carlton, K. H. Kim, Y. T. Liu, and K. M. Newell (1993) to movement, and (b) the movement spatial and temporal outcome variability are complementary and well predicted by an equation treating the variance of force and time in Newton's 2nd law as independent random variables. Collectively, the findings suggest that movement outcome variability is the product of a coherent space—time function that is driven by the nonlinear scaling of the force—time properties of the initial impulse.

Adhesion mapping of chemically modified and poly(ethylene oxide)-grafted glass surfaces

Two-dimensional mapping of the adhesion pull-off forces was used to study the origin of surface heterogeneity in the grafted poly(ethylene oxide) (PEO) layer. The variance of the pull-off forces measured over the μm-sized regions after each chemical step of modifying glass surfaces was taken to be a measure of the surface chemical heterogeneity. The attachment of γ-glycidoxypropyltrimethoxy silane (GPS) to glass decreased the pull-off forces relative to the clean glass and made the surface more uniform. The subsequent hydrolysis of the terminal epoxide groups resulted in a larger surface heterogeneity which was modeled by two populations of the terminal hydroxyl groups, each with its own distribution of adhesion forces and force variance. The activation of the hydroxyls with carbonyldiimmidazole (CDI) healed the surface and lowered its adhesion, however, the force variance remained rather large. Finally, the grafting of the α,ω-diamino poly(ethyleneoxide) chains to the CDI-activated glass largely eliminated adhesion except at a few discrete regions. The adhesion on the PEO grafted layer followed the Poisson distribution of the pull-off forces. With the exception of the glass surface, a correlation between the water contact angles and the mean pull-off forces measured with the Si 3N 4 tip surfaces was found for all modified glass surfaces.

Contribution of jaw muscle size and craniofacial morphology to human bite force magnitude.

The existence of an interaction among bite force magnitude, jaw muscle size (e.g., cross-sectional area, thickness), and craniofacial morphology is widely accepted. Bite force magnitude depends on the size of the jaw muscles and the lever arm lengths of bite force and muscle forces, which in turn are dictated by craniofacial morphology. In this study, the relative contributions of craniofacial morphology and jaw muscle thickness to the bite force magnitude were studied. In 121 adult individuals, both magnitude and direction of the maximal voluntary bite force were registered. Craniofacial dimensions were measured by anthropometrics and from lateral radiographs. The thicknesses of the masseter, temporal, and digastric muscles were registered by ultrasonography. After a factor analysis was applied to the anthropometric and cephalometric dimensions, the correlation between bite force magnitude, on the one hand, and the "craniofacial factors" and jaw muscle thicknesses, on the other, was assessed by stepwise multiple regression. Fifty-eight percent of the bite force variance could be explained. From the jaw muscles, only the thickness of the masseter muscle correlated significantly with bite force magnitude. Bite force magnitude also correlated significantly positively with vertical and transverse facial dimensions and the inclination of the midface, and significantly negatively with mandibular inclination and occlusal plane inclination. The contribution of the masseter muscle to the variation in bite force magnitude was higher than that of the craniofacial factors.

A simple optimal pole location technique for structural control

An optimal pole placement technique is proposed for the vibration control of a structure modeled as a single-degree-of-freedom system subjected to a white noise ground excitation. The objective of the proposed technique is to shift the closed-loop poles into a prescribed region in the complex plane using the smallest amount of control force variance. The Kuhn-Tucker necessary condition and the second order necessity and sufficiency theorem are used to solve for the control gain and the corresponding optimal pole locations in the prescribed region. Using independent modal space control theory, the algorithm is extended to the control of a multiple-degree-of-freedom system with incomplete state measurements using limited number of sensors. The performance and stability of the control algorithm are numerically verified on the control of two buildings. Two control devices, active tendon and active mass driver, are used to demonstrate the implementation of the current development. The results show that the technique provide an alternative design methodology for these two control devices to mitigate structural response due to earthquake excitation.