Center of Gravity

Sounds convey information about the materials composing an object. Stimuli were synthesized using a computer model of impacted plates that varied their material properties: viscoelastic and thermoelastic damping and wave velocity ͑related to elasticity and mass density͒. The range of damping properties represented a continuum between materials with predominant viscoelastic and thermoelastic damping ͑glass and aluminum, respectively͒. The perceptual structure of the sounds was inferred from multidimensional scaling of dissimilarity judgments and from their categorization as glass or aluminum. Dissimilarity ratings revealed dimensions that were closely related to mechanical properties: a wave-velocity-related dimension associated with pitch and a damping-related dimension associated with timbre and duration. When asked to categorize sounds, however, listeners ignored the cues related to wave velocity and focused on cues related to damping. In both dissimilarity-rating and identification experiments, the results were independent of the material of the mallet striking the plate ͑rubber or wood͒. Listeners thus appear to select acoustical information that is reliable for a given perceptual task. Because the frequency changes responsible for detecting changes in wave velocity can also be due to changes in geometry, they are not as reliable for material identification as are damping cues.

The aim of the study was to confirm the hypothesis that the longer a contraction is sustained, the larger are the changes in the spatial distribution of muscle activity. For this purpose, surface electromyographic (EMG) signals were recorded with a 13 · 5 grid of electrodes from the upper trapezius muscle of 11 healthy male subjects during static contractions with shoulders 90°abducted until endurance. The entropy (degree of uniformity) and center of gravity of the EMG root mean square map were computed to assess spatial inhomogeneity in muscle activation and changes over time in EMG amplitude spatial distribution. At the endurance time, entropy decreased (mean ± SD, percent change 2.0 ± 1.6%; P < 0.0001) and the center of gravity moved in the cranial direction (shift 11.2 ± 6.1 mm; P < 0.0001) with respect to the beginning of the contraction. The shift in the center of gravity was positively correlated with endurance time (R 2 = 0.46, P < 0.05), thus subjects with larger shift in the activity map showed longer endurance time. The percent variation in average (over the grid) root mean square was positively correlated with the shift in the center of gravity (R 2 = 0.51, P < 0.05). Moreover, the shift in the center of gravity was negatively correlated to both initial and final (at the endurance) entropy (R 2 = 0.54 and R 2 = 0.56, respectively; P < 0.01 in both cases), indicating that subjects with less uniform root mean square maps had larger shift of the center of gravity over time. The spatial changes in root mean square EMG were likely due to spatially-dependent changes in motor unit activation during the sustained contraction. It was concluded that the changes in spatial muscle activity distribution play a role in the ability to maintain a static contraction.

Respiration-induced movement of the upper abdominal organs (pancreas, liver and kidneys) was assessed in 12 subjects using dynamic magnetic resonance imaging. The movement of each organ in the cranio-caudal, the lateral and the anterior-posterior direction was deduced from the movement of the center of gravity on two-dimensional images. This center of gravity was computed from the volume delineated on sequential 8-mm slices of both sagittal and coronal dynamic series. The largest movements were noticed in the cranio-caudal direction for pancreas and liver (23.7^15.9 mm and 24.4^16.4 mm). The kidneys showed smaller movements in the cranio-caudal direction (left kidney 16.9^6.7 mm and right kidney 16.1^7.9 mm). The movements of the different organs in the anterior-posterior and lateral directions were less pronounced. It is of the greatest importance to be aware of these movements in the planning of a conformal radiation treatment for pancreatic cancer. q

A fuzzy clustering-based hybrid method for a multi-facility location problem is presented in this study. It is assumed that capacity of each facility is unlimited. The method uses different approaches sequentially. Initially, customers are grouped by spherical and elliptical fuzzy cluster analysis methods in respect to their geographical locations. Different numbers of clusters are experimented. Then facilities are located at the proposed cluster centers. Finally each cluster is solved as a single facility location problem. The center of gravity method, which optimizes transportation costs is employed to fine tune the facility location. In order to compare logistical performance of the method, a real world data is gathered. Results of existing and proposed locations are reported.

A balance platform setup was defined for use in the determination of the center of gravity in the sagittal plane for a wheelchair and patient. Using the center of gravity information, measurements from the wheelchair and patient (weight, tire coefficients of friction), and various assumptions (constant speed, level-concrete surface, patient-wheelchair system is a rigid body), a method for estimating the rolling resistance for a wheelchair was outlined. The center of gravity and rolling resistance techniques were validated against criterion values (center of gravity error = 1 percent, rolling resistance root mean square error = 0.33 N, rolling resistance Pearson correlation coefficient = 0.995). Consistent results were also obtained from a test dummy and five subjects. Once the center of gravity is known, it is possible to evaluate the stability of a wheelchair (in terms of tipping over) and the interaction between the level of stability and rolling resistance. These quantitative measures are expected to be of use in the setup of wheelchairs with a variable seat angle and variable wheelbase length or when making comparisons between different wheelchairs.

. The behavioral responses of schools of young Koi fish Cyprinus carpio to sub-lethal ammonia concentrations were monitored using CCD cameras and computer image processing. Several geometrical parameters of the schools such as the position of the center of gravity, and the distribution of the fish were calculated continuously and plotted versus time. Swimming speed and activity were measured indirectly through a novel parameter-the Projected Mobility Picture Ž . PMP . The immediate response of the treated fish was to dive to the bottom of the tank and stay there for a time period which increased with the ammonia concentration. Later, the fish rose to depths which increased with ammonia concentration. At high ammonia concentration, the fish approached the surface. Decreased activity of the treated fish was accompanied by a smaller mean distribution. Blood glucose levels of the treated fish increased, and they became indifferent to food. In general, this remote method of continuous monitoring of alterations in fish behavior under stress has the potential to be developed into a method for detecting early signs of stress in populations of fish. q

This paper compares four observers (virtual sensors) of vehicle sideslip angle and lateral forces. The first is linear and uses a linear vehicle model. The remaining observers use an extended nonlinear model. The three nonlinear observers are: extended Luenberger observer, extended Kalman filter and sliding-mode observer. Modeling, model simplification, and observers are described, and an observability analysis is performed for the entire vehicle trajectory. The paper also deals with three different sets of sensors to see the impact of observers results. Comparison is first done by simulation on a valid vehicle simulator, and then observers are used on experimental data. Our study shows that observers are more accurate than simple models as regards unmeasurable variables such as sideslip angle and transversal forces. It also shows that speed of center of gravity is not an indispensable variable here.

Ο Καρλ Φον Κλαούζεβιτς είναι αδιαμφισβήτητα ο θεωρητικός του πολέμου ο οποίος, περισσότερο από οποιονδήποτε άλλο, επηρέασε τη σκέψη τόσο των συγχρόνων όσο και των νεωτέρων του θεωρητικών της πολεμικής τέχνης. Ο Κλαούζεβιτς ανέπτυξε τη θεωρία του στο μοναδικό του έργο με τον τίτλο On War, το οποίο ο ίδιος χαρακτήρισε ημιτελές και το οποίο εξέδωσε η σύζυγός του το 1932 μετά το θάνατό του. Ο Peter Paret το θεωρεί μακράν το έργο με τη μεγαλύτερη επιρροή σε θέματα στρατιωτικής τέχνης, το οποίο έχει γραφεί ποτέ. Πάνω από εκατόν εβδομήντα χρόνια μετά το θάνατο του συγγραφέα του, εξακολουθεί να μελετάται σε σχεδόν κάθε Σχολή Διοίκησης και Επιτελών και Σχολή Πολέμου του πάλαι ποτέ Δυτικού κόσμου, και όχι μόνο. Παρόλα αυτά το βιβλίο είναι δυσανάγνωστο. Ο στρατηγός George Patton, μελετητής ο ίδιος του Κλαούζεβιτς, έλεγε: “Αυτό το βιβλίο δεν είναι δυνατόν να γίνει κατανοητό με την πρώτη ανάγνωση. Ορισμένα μέρη του είναι δυσνόητα και επιδέχονται περισσότερες από μία ερμηνείες, ενώ άλλα απαιτούν συγκέντρωση, επαναληπτική ανάγνωση και ανάλυση σε αίθουσα διδασκαλίας”.

This paper describes the kinematics and muscle activity associated with the standard sit-up, as a first step in the investigation of complex motor coordination. Eight normal human subjects lay on a force table and performed at least 15 sit-ups, with the arms across the chest and the legs straight and unconstrained. Several subjects also performed sit-ups with an additional weight added to the head. Support surface forces were recorded to calculate the location of the center of pressure and center of gravity; conventional motion analysis was used to measure segmental positions; and surface EMG was recorded from eight muscles. While the sit-up consists of two serial components, 'trunk curling' and 'footward pelvic rotation', it can be further subdivided into five phases, based on the kinematics. Phases I and II comprise trunk curling. Phase I consists of neck and upper trunk flexion, and phase II consists of lumbar trunk lifting. Phase II corresponds to the point of peak muscle contraction and maximum postural instability, the 'critical point' of the sit-up. Phases III-V comprise footward pelvic rotation. Phase III begins with pelvic rotation towards the feet, phase IV with leg lowering, and phase V with contact between the legs and the support surface. The overall pattern of muscle activity was complex with times of EMG onset, peak activity, offset, and duration differing for different muscles. This complex pattern changed qualitatively from one phase to the next, suggesting that the roles of different muscles and, as a consequence, the overall form of coordination, change during the sit-up. 

Radiocarbon measurements by two 1220 Quantulus™ ultra low background liquid scintillation spectrometers were performed at the underground laboratory of Gran Sasso and the Radiocarbon Laboratory of E.N.E.A.-Bologna to study the efficiency and background variations related to measurement sites. The same configuration setup, i.e. the same center of gravity of the 14 C spectrum (SQP(I) = 410 ± 1) was obtained in both instruments. Many different background and modern standards with pure analytical benzene were used and spectra for 40 one-hour periods were obtained. The data indicates a background reduction of approximately 65% between the surface and underground laboratories, with no differences in the efficiency. Recording similar efficiencies in both spectrometers is probably due to fairly identical photomultiplier characteristics. The cosmic noise reduction observed at the laboratory of Gran Sasso makes it possible to perform high precision 14 C measurements and to extend for these idealized samples the present maximum dating limit from 58,000 BP to 62,000 BP (5 mL, 3 days counting).

Dynamic stability of vehicles is a major concern to vehicle manufacturers, as this determines how safe a vehicle will be on the road, to passengers and other road users. The location of centre of gravity (CG) on a vehicle determines its stability. The objective of this work is to evaluate the dynamic stability of a modeled cargo tricycle. The mass Properties capability of the SolidWorks software was used to determine the CG location on the tricycle. Result shows that the model will response to side load with a yaw motion and it’s an oversteer vehicle. Therefore it is unstable at high speed above its critical speed. The rollover threshold (Fc) for the tricycle model is 0.32g.

This paper contains a critical review of available methodology for dealing with the motion of non-spherical particles at higher Reynolds numbers in the Eulerian-Lagrangian methodology for dispersed flow. First, an account of the various attempts to classify the various shapes and the efforts towards finding a universal shape parameter is given and the details regarding the significant secondary motion associated with nonspherical particles are outlined. Most investigations concerning large non-spherical particles to date have been focused on finding appropriate correlations of the drag coefficient for specific shapes either by parameter variation or by using shape parameters. Particular emphasis is here placed on showing the incapability of one-dimensional shape parameters to predict the multifaceted secondary motion associated with non-spherical particles. To properly predict secondary motion it is necessary to account for the noncoincidence between the center of pressure and center of gravity which is a direct consequence of the inertial pressure forces associated with particles at high Reynolds number flow. Extensions for non-spherical particles at higher Reynolds numbers are far in between and usually based on semi-heuristic approaches utilizing concepts from airfoil theory such as profile lift. Even for regular particles there seems to be a long way before a complete theory can be formulated. For irregular particles with small aspect ratio, where the secondary motion is insignificant compared to the effect of turbulence, the drag correlations based on onedimensional shape parameters come to their right. The interactions between non-spherical particles and turbulence are not well understood and modeling attempts are limited to extending methods developed for spheres.

The article asks the question, Is the Center of Gravity (CoG) concept still relevant in today’s Operational Environment (OE)? It explores the two main schools of thought that argue irrelevancy: unsettled theory and the technological, and philosophical differences between the 18th and 21st centuries. Then the article rebuts the arguments by demonstrating the concept’s utility to planning and its timeless applicability that is independent of shifting philosophical thought.

The Clausewitzian Center of Gravity (COG) concept is central in western military strategic thinking and serves as a core concept in military planning.  However, several interpretations of the concept exist, which contributes to theoretical as well as practical confusion.  Moreover, the concept receives critique such as “it is so abstract to be meaningless,” “it fails to provide convincing evidence for its use at the strategic level of war,” “there is a lack of interdisciplinary awareness,” it is an analogy tailored to Prussian military challenges in the early 19th Century, etc.  This article contributes to the discussion by combining the COG concept with strategic theory, hereby addressing many of the raised critique points.  The article presents three COG-Strategy schools, centered on different/competing interpretations of the Clausewitzian Center of Gravity (CoG) concept as well as different approaches to strategy.  Each CoG-strategy school is rooted in the experiences as well as the historical roles of the individual U.S. military services and expresses a distinct, ideal-type way of fighting and winning wars.  The article finishes with a discussion of how the COG concept can connect a grand strategy to the military strategy.  For this purpose, it introduces the Will and Ability COG concept, which belongs to COG-Strategy school three (see below).  The Will and Ability COG concept provides strategists a method for designing war winning strategies that focus on inducing a policy change by the adversary leadership and on defeating the adversary’s strategy, starting at the grand strategic level of war and with the lower levels providing increasingly more details to various elements of the grand strategy.

This paper is devoted to study and verify the suitability of the expanded polypropylene (EPP) foam as a liner for motorcycle helmet and to perform helmet design optimization. This EPP foam has a multi-impact protection performance and also has a potential for ventilation system improvement due to its resiliency. This resiliency allows for the ease of ventilation holes and channels molding without the foam breakage at the stage of mold extraction. The large scale, non-linear, dynamic finite element package LS-DYNA3D is used as a verification tool for motorcycle helmet design. Then the simulation work is carried further to provide data for helmet design analysis and optimization using the response surface methodology (RSM). The foam thickness, the foam density, and shell thickness being selected as the design factors for the response surface generation and design optimization. The results showed that the EPP satisfies the 300g headform center of gravity acceleration limit required by most of the international standards. The extended simulation output data is then used to create the response surface and determine the optimum design points. Therefore, two main contributions on motorcycle helmet design are achieved. The first is on the use of the EPP as a helmet energy absorption liner for the motorcycle helmet application, and the second is that by combining the simulation output with the design of experiment (DOE) method to study the effects of the various factors on helmet design optimization.

In this paper we present a methodology based on multiple models and switching for realtime estimation of center of gravity (CG) position in automotive vehicles. The method utilizes well-known simple linear vehicle models for lateral and roll dynamics and assumes the availability of standard stock automotive sensors. We illustrate the technique with numerical simulations as well as with measured sensor

This paper aims at developing a technically sound and conceptually engineered ATV called quad bike. This paper describes in detail the procedure followed, methodology used and the considerations made in the entire design process. First the design approach is discussed and then the resulting design procedure and design analysis has been explained. Due efforts have been put to validate the design by theoretical calculations, simulations and known facts. Through this paper, an effort has been made to introduce a reliable yet cheaper methodology for industrial quad bike designing and simulation that may be used as a reference for many upcoming industries as well as many research and development projects.

Fixed wing micro air vehicles (wingspan between 10 and 15 cm) are aerodynamically challenging due to the low Reynolds number regime (10 4 -10 5 ) they operate in. The low aspect ratio wings (typically used to maximize area under a size constraint) promote strong tip vortices, and are susceptible to rolling instabilities. Wind gusts can be of the same order of magnitude as the flight speed (10-15 m/s). Standard control surfaces on an empennage must be eliminated for size considerations and drag reduction, and the range of stable center of gravity locations is only a few millimeters long. Membrane aeroelasticity has been identified has a tenable method to alleviate these issues: flexible wing structures with geometric twist (adaptive washout for gust rejection, delayed stall) and aerodynamic twist (adaptive inflation for high lift, larger stability margins) are both considered here. Recent investigations in static aeroelastic characterization, including flight loads, wing deformation, flow structures, aeroelastic tailoring studies through laminate orientation, as well as unconventional techniques based on membrane pre-tension, are reviewed. Multi-objective optimization aimed at improving lift, drag, and pitching moment considerations is also discussed.

In most motor acts, posture and movement must be coordinated in order to achieve the goal of the task. The focus of this chapter is on why and how this coordination takes place. First, the nature of posture is discussed. Two of its general functions are recognized; an antigravity role, and a role in interfacing the body with its environment such that perception and action can ensue. Next addressed is how posture is controlled centrally. Two models are presented and evaluated; a genetic and a hierarchical one. The latter has two levels; internal representation and execution. Finally, we consider how central control processes might achieve an effective coordination between posture and movement. Is a single central control process responsible for both movement and its associated posture? Alternatively, is there a dual coordinated control system: one for movement, and the other for posture? We provide evidence for the latter, in the form of a biomechanical analysis that features the use of eigenmovement approach.

Received Accepted 13 Displacement of the center of gravity (COG) of tubular structures with various polygonal cross-sections is numerically investigated under an axial crush using the program 15 code of ANSYS/LS-DYNA. A subroutine is developed using this code to calculate the COG of the deformed shape, during and after the crush. The effect of wall thickness on 17 displacement of the COG is also investigated. Displacement of the COG decreases as the number of edges increases; it is a reasonable symmetric-deformed shape for the number 19 of edges beyond eight. An even number of edges leads to a more symmetric displacement of the COG. The effect of the number of polygonal edges on symmetric deformation of 21 the COG becomes more prominent as the initial wall thickness decreases. The higher number of edges stabilizes the deformed shape and the value of the mass moment of 23 inertia of the deformed shape about the y axis (Iyy). The value of the mass moment of inertia about the x-z axes (Ixz) in comparison with Iyy can be neglected in the case 25 of dealing with an axial crush along the y direction.

This paper presents an emergency stop algorithm of a walking humanoid robot. There are many cases which force a walking robot to stop quickly without falling. Since an emergency occurs at unpredictable timing and at any state of robot, the stopping motion must be generated in real-time.

Abstract—We study models of a quadrotor UAV. These models include various aerodynamic effects of the propellers and their interactions with the motion of the rigid body of the UAV. Two main assumptions are formulated: the twisting of the propellers is such that the local ...

Because we love Carl von Clausewitz and the center of gravity concept, we need to grant them a divorce-for our sake. We tried for years to make it work, but it's time to face reality, together they are just too abstract and confusing for us to embrace.

In this paper, we present a methodology based on multiple models and switching for real-time estimation of center of gravity (CG) position and rollover prevention in automotive vehicles. Based on a linear vehicle model in which the unknown parameters appear nonlinearly, we propose a novel sequential identification algorithm to determine the vehicle parameters rapidly in real time. The CG height estimate is further coupled with a switching controller to prevent un-tripped rollover in automotive vehicles. The efficacy of the proposed switched multi model/controller estimation and control scheme is demonstrated via numerical simulations.

Eye-hand coordination was investigated with the global effect paradigm. In this paradigm, saccades typically land in between the target and a nearby presented distractor, the configuration's center of gravity. This so-called global effect, or spatial averaging, is attributed to incomplete target selection. Four experiments demonstrated a similar effect for hand movements; thus, eye and hand are coupled during target selection. However, under some conditions the global effect was different for eye and hand, suggesting that their coupling is not achieved through a shared target representation. Instead, eye and hand seem to use 2 separate target representations that exchange information. The convergent amplitudes of eye and hand with simultaneous execution support this interpretation. Latencies showed a similar converging pattern.

In this paper we present an adaptive controller implementation based on the multiple models, switching, and tuning (MMST) paradigm for preventing un-tripped rollover in automotive vehicles. Our approach relies on differential-braking to keep the value of the Load Transfer Ratio (LT R) below a threshold. We first employ multiple models to infer the unknown center of gravity height and the suspension parameters of the vehicle, which are subsequently used to switch to the corresponding rollover controller. The proposed multi-controller switched scheme is shown via numerical simulations to result in better performance than its fixed robust counterpart.

This paper studies the balance of a humanoid robot carrying a heavy object. Without knowing the mass and the position of the center of gravity of the object, the humanoid robot carries a heavy object stably by using the force sensor information attached at the wrists and the ankles. We first show how to generate the motion of a humamoid robot by taking the force sensor information into consideration. We also show the method for generating the gait pattern by taking the dynamics of the carried object. The effectiveness of the proposed method is shown by experiments.

This paper proposes a simple measure of the World's Economic Center of Gravity (WECG) based on national GDP figures and the geographical location of the world's most important cities. This measure makes it possible to characterize the location of economic activity around the globe. It turns out that, over the 1975-2004 period, the WECG has shifted towards Asia, and the location of economic activity has become more evenly spread. On average, the distance to the WECG, which is highly correlated with the remoteness indicator frequently used in the trade gravity literature, has decreased more in Asian cities (-12%) and increased more in European cities (+16%).

Purpose -To perform the flapwise bending vibration analysis of a rotating cantilever Timoshenko beam. Design/methodology/approach -Kinetic and potential energy expressions are derived step by step. Hamiltonian approach is used to obtain the governing equations of motion. Differential transform method (DTM) is applied to solve these equations.

Abstract⎯ The experimental single sided linear motor maglev vehicle ME02 available in our laboratory is levitated and propelled by permanent magnet linear synchronous motor (PM LSM). To eliminate the undesired pitching motion resulting from the unbalanced torques developed around the vehicle center of gravity, two air-cored electromagnets (AEM) are located in the vehicle's most front and rear. The proposed electromagnets are feed with controlled current such that the developed torque works against the pitching torque. In the current paper, analytical voltage model for the AEM is introduced. The model is based on derivation of the analytical solution of the multilayer boundary field problem of PM LSM. A voltage chopper is utilized in its current regulated mode to track the demand current required to damp the pitching motion. To validate the effectiveness of the proposed system, simulated study for pitching motion control is carried out with the mass and location of center of gravity are taken as disturbances. The results show the robustness of the introduced control scheme.

Did living standards stagnate before the Industrial Revolution? Traditional real-wage indices typically show broadly constant living standards before 1800. In this paper, we show that living standards rose substantially, but surreptitiously because of the growing availability of new goods. Colonial luxuries such as tea, coffee, and sugar transformed European diets after the discovery of America and the rounding of the Cape of Good Hope. These goods became household items in many countries by the end of the 18th century. We use the Greenwood-Kopecky (2009) method to calculate welfare gains based on data about price changes and the rate of adoption of new colonial goods. Our results suggest that by 1850, the average Englishman would have been willing to forego 15% or more of his income in order to maintain access to sugar and tea alone. These findings are robust to a wide range of alternative assumptions, data series, and valuation methods.

Equilibrium reactions were compared between male and female adolescents (prepuberal and puberal), classified into two groups: those who had previously learned complex motor tasks (dance or acrobatics) and those with no particular training. Subjects stood (eyes open or eyes closed) on a free seesaw platform, the displacements of which were calculated from accelerometer measures. They were instructed to maintain a vertical position with their frontal plane either parallel (to measure antero-posterior oscillations) or perpendicular to the axis of the platform (to measure lateral oscillations). Girls had a better stability than boys as shown by the smaller displacements of their center of gravity. Untrained subjects, irrespective of sex, were the least stable. Subjects trained in acrobatics were more stable than dancers. Differences related to sex can be attenuated by physical training involving equilibrium exercises which suggests that moderate sustained training could reduce the incidence of falls in aged persons and in professionally exposed workers. dynamic equilibrium I body sway I sport training I sex I classical ballet I acrobats

"Elevated age in cyber warfare
Malware has become focused
SCADA Systems (Stuxnet)
Malware performs Operational Preparation of the Environment (OPE)
Conficker (Millions still infected)
Ransomeware
Data is being held hostage
The advanced capability of the threat has increased the risk.
Understanding the risk allows employment of defensive measures to mitigate the risk – “Risk will always be present”"

This paper presents the design and preliminary control of an indoor coaxial helicopter "CoaX" based on a concept of hybrid active and passive control. The robot is capable of passive roll and pitch stabilization against small disturbances while actively stabilizing the yaw and the altitude. We achieve omnidirectional horizontal motion by shifting the center of gravity. The structure is made out of lightweight polyurethane and carbon fiber. Preliminary tests show that "CoaX" is able to hover for short moments and the lateral control is effective.

Center of mass displacement during gait has frequently been used as an indicator of gait efficiency or as a complement to standard gait analysis. With technological advances, measuring the center of mass as the centroid of a multi-segment system is practical and feasible, but must first be compared to the well-established Newtonian computation of double-integrating the ground reaction force. This study aims to verify that the kinematic centroid obtained from a commonly-used model (Vicon PeakÒ Plug-In-Gait) provides at least as reliable measurements of center of mass displacement as those obtained from the ground reaction forces. Gait data was collected for able-bodied children and children with myelomeningocele who use larger lateral center of mass excursions during gait. Reasonable agreement between methods was found in fore-aft and vertical directions, where the methods' excursions differed by an average of less than 10 mm in either direction, and the average RMS differences between methods' computed curves were 6 and 13 mm. Particularly good agreement was observed in the lateral direction, where the calculated excursions differed by an average of less than 2 mm and the RMS difference was 5 mm. Error analyses in computing the center of mass displacement from ground reaction forces were performed. A 5% deviation in mass estimation increased the computed vertical excursion twofold, and a 5% deviation in the integration constant of initial velocity increased the computed fore-aft excursions by 10%. The suitability of calculating center of mass displacement using ground reaction forces in a patient population is questioned. The 0167-9457/$ -see front matter Ó (E.M. Gutierrez-Farewik).

The main goal of this study is the use of polynomial chaos expansion (PCE) to analyze the uncertainty in calculating the lateral and longitudinal center of gravity for a vehicle from static load cell measurements. A secondary goal is to use experimental testing as a source of uncertainty and as a method to confirm the results from the PCE simulation.

We provide data on Centers of Gravity (COG) and resonances of two spectral peaks (P1 and P2) in bark-scaled acoustic spectra of N|uu lingual (L) (ʘ, ǀ, ǃ, ǁ, ǂ) and linguo-pulmonic (LP) stops: (ʘ°q, ǀ°q, ǃ°q, ǁ°q, ǂ°q). COG, P1 and P2 values for click bursts in L and LP stops do not differ, indicating that the L/LP contrast

A high precision dense grid of reference lines in the hyperfine structure of the B-X system of molecular iodine ( 127 I 2 ) is presented. A simple parametrization has been derived, predicting the hyperfine line positions of the ''t'' components for vibrational bands (13-1) up to (18-1) and rotational quantum numbers J Å (9-140). The analysis in this paper is based on Doppler-free saturation spectroscopy spectra used for calibration of more than 100 new components in the hyperfine structure of 127 I 2 . The data presented contains a prediction (with 2 MHz accuracy) for the positions of 1584 ''t'' components in the rotational structure of iodine, covering the wavelength interval 571-596 nm. ᭧ 1998 Academic Press