An optimized tuned mass damper/harvester device

Much work has been conducted on vibration absorbers, such as tuned mass dampers (TMD), where significant energy is extracted from a structure. Traditionally, this energy is dissipated through the devices as heat. In this paper, the concept of recovering some of this energy electrically and reuse it for structural control or health monitoring is investigated. The energy-dissipating damper of a TMD is replaced with an electromagnetic device in order to transform mechanical vibration into electrical energy. That gives the possibility of controlled damping force whilst generating useful electrical energy. Both analytical and experimental results from an adaptive and a semi-active tuned mass damper/harvester are presented. The obtained results suggest that sufficient energy might be harvested for the device to tune itself to optimise vibration suppression

CROPSTATUS--A Computer Program to Assess the Effects of Seasonal Weather Changes on Nebraska\u27s Agriculture

CROPSTATUS is a series of programs residing in Nebraska\u27s AGNET system using daily weather data to assess seasonal changes in crops, livestock, and other agricultural conditions. Assessments are based on parameters developed from accumulations of current daily temperature and precipitation data collected from a network of synoptic, climate, and automated micrometeorological stations in Nebraska in comparison with daily normals. The daily normals were derived from monthly summaries using multiple regression models to compute daily values as a function of Julian day numbers. Crop phenology models based on growing degree days were used to monitor and forecast the progress of different crop strains and times of planting. Biological time scale statistical yield models are used for production estimates. Weather probability information is also available from CROPSTATUS. Long term climatic records have been used to determine spring and autumn freeze probabilities, preseason precipitation available for subsoil moisture recharge and the probabilities of weekly averages of daily maximum and minimum temperatures. These and other features are available in a menu of over 20 different agricultural weather information items developed from a network of 60 weather stations. CROPSTATUS is also used to prepare tabular data and computer maps showing changes in conditions throughout the state. These maps are used in meetings by an interdisciplinary committee of agricultural extension specialists to prepare weekly agweather situation/advisory reports

CROPSTATUS--A Computer Program to Assess the Effects of Seasonal Weather Changes on Nebraska\u27s Agriculture

CROPSTATUS is a series of programs residing in Nebraska\u27s AGNET system using daily weather data to assess seasonal changes in crops, livestock, and other agricultural conditions. Assessments are based on parameters developed from accumulations of current daily temperature and precipitation data collected from a network of synoptic, climate, and automated micrometeorological stations in Nebraska in comparison with daily normals. The daily normals were derived from monthly summaries using multiple regression models to compute daily values as a function of Julian day numbers. Crop phenology models based on growing degree days were used to monitor and forecast the progress of different crop strains and times of planting. Biological time scale statistical yield models are used for production estimates. Weather probability information is also available from CROPSTATUS. Long term climatic records have been used to determine spring and autumn freeze probabilities, preseason precipitation available for subsoil moisture recharge and the probabilities of weekly averages of daily maximum and minimum temperatures. These and other features are available in a menu of over 20 different agricultural weather information items developed from a network of 60 weather stations. CROPSTATUS is also used to prepare tabular data and computer maps showing changes in conditions throughout the state. These maps are used in meetings by an interdisciplinary committee of agricultural extension specialists to prepare weekly agweather situation/advisory reports

Comparison of washing methods and smear conservation periods for llama sperm acrosome assessment using the Coomassie blue stain

El objetivo de este trabajo fue comparar métodos de lavado y conservación de frotis para evaluar el acrosoma en espermatozoides de llama mediante la tinción con Coomassie Blue (CB), con el propósito de facilitar la técnica e independizar los momentos de la extracción de semen de la evaluación de los acrosomas espermáticos. Se procesaron 12 eyaculados, se probaron dos tipos de lavado de los frotis fijados (con PBS o solución fisiológica, SF) y se evaluaron diferentes temperaturas (5º C y temperatura ambiente) y tiempos (0, 1 y 7 días) de conservación. Se evaluaron los siguientes frotis (cada uno lavado con PBS o con SF): 1) fijados, teñidos y evaluados el mismo día de la extracción; 2) fijados, teñidos y conservados 24 hs a temperatura ambiente y luego evaluados; 3) fijados, conservados a 4º C durante 1 día y luego teñidos y evaluados; 4) fijados, conservados a 4º C durante 7 días y luego teñidos y evaluados. Se evaluaron un total de 8 frotis por eyaculado. No se observaron diferencias significativas en el porcentaje de acrosomas presentes evaluado por CB entre las dos metodologías de lavado de los frotis fijados, ni entre las diferentes temperaturas y los diferentes tiempos de conservación de los frotis. Conclusión: es posible utilizar solución fisiológica para lavar los frotis fijados facilitando la técnica de CB para evaluar la presencia de los acrosomas en espermatozoides de llama. Además, se logró independizar los momentos de la extracción de semen de la evaluación de los acrosomas espermáticos.The objective of this study was to compare washing methods and smear conservation periods for llama sperm acrosome assessment using the Coomassie Blue stain, with the aim of facilitating the technique and to allow the moment of sperm acrosome evaluation become independent of the moment of semen collection. Twelve ejaculates were processed; two types of washing of the smears (with PBS or with physiologic solution, PS) and different temperatures (5 ºC and room temperature) and periods of conservation (0, 1 and 7 days) were assessed. The following smears were evaluated: 1) fixed, stained and evaluated the same day of collection; 2) fixed, stained and conserved for 24 hours at room temperature and then evaluated; 3) fixed, conserved at 4º C for 1 day and then stained and evaluated and 4) fixed, conserved at 4º C for 7 days and then stained and evaluated. A total of 8 smears per ejaculate were evaluated. No significant differences were observed in the percentages of acrosomes present, evaluated by CB, between both types of washing of the fixed smears, nor between the different temperatures and conservation periods of the fixed smears. Conclusions: it is possible to use physiologic solution to wash the fixed smears, thus facilitating the Coomassie Blue technique used to evaluate the presence of llama sperm acrosomes. In addition, it was possible to separate the moment of sperm acrosome evaluation from the semen collection.Fil: Fumuso, Fernanda Gabriela. Universidad de Buenos Aires. Facultad de Cs.veterinarias. Area de Teriogenologia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Gimenez, M. L.. Universidad de Buenos Aires. Facultad de Cs.veterinarias. Area de Teriogenologia; ArgentinaFil: Neild, Debora Margarita. Universidad de Buenos Aires. Facultad de Cs.veterinarias. Area de Teriogenologia; ArgentinaFil: Giuliano, Susana María. Universidad de Buenos Aires. Facultad de Cs.veterinarias. Area de Teriogenologia; ArgentinaFil: Chaves, M. G.. Universidad de Buenos Aires. Facultad de Cs.veterinarias. Area de Teriogenologia; ArgentinaFil: Carretero, Maria Ignacia. Universidad de Buenos Aires. Facultad de Cs.veterinarias. Area de Teriogenologia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Inverse dynamics modelling of upper-limb tremor, with cross-correlation analysis

A method to characterise upper-limb tremor using inverse dynamics modelling in combination with cross-correlation analyses is presented. A 15 degree-of-freedom inverse dynamics model is used to estimate the joint torques required to produce the measured limb motion, given a set of estimated inertial properties for the body segments. The magnitudes of the estimated torques are useful when assessing patients or evaluating possible intervention methods. The cross-correlation of the estimated joint torques is proposed to gain insight into how tremor in one limb segment interacts with tremor in another. The method is demonstrated using data from a single patient presenting intention tremor because of multiple sclerosis. It is shown that the inertial properties of the body segments can be estimated with sufficient accuracy using only the patient's height and weight as a priori knowledge, which ensures the method's practicality and transferability to clinical use. By providing a more detailed, objective characterisation of patient-specific tremor properties, the method is expected to improve the selection, design and assessment of treatment options on an individual basis

Simplifying transformations for nonlinear systems: Part I, an optimisation-based variant of normal form analysis

This paper introduces the idea of a ‘simplifying transformation’ for nonlinear structural dynamic systems. The idea simply stated; is to bring under one heading, those transformations which ‘simplify’ structural dynamic systems or responses in some sense. The equations of motion may be cast in a simpler form or decoupled (and in this sense, nonlinear modal analysis is encompassed) or the responses may be modified in order to isolate and remove certain components. It is the latter sense of simplification which is considered in this paper. One can regard normal form analysis in a way as the removal of superharmonic content from nonlinear system response. In the current paper, this problem is cast in an optimisation form and the differential evolution algorithm is used

Low Order Model for the Dynamics of Bi-Stable Composite Plates

This article presents the derivation and validation of a low order model for the non-linear dynamics of cross-ply bi-stable composite plates focusing on the response of one stable state. The Rayleigh–Ritz method is used to solve the associated linear problem to obtain valuable theoretical insight into how to formulate an approximate non-linear dynamic model. This allows us to follow a Galerkin approach projecting the solution of the non-linear problem onto the mode shapes of the linear problem. The order of the non-linear model is reduced using theoretical results from the linear solution yielding a low order model. The dynamic response of a bi-stable plate specimen is studied to simplify the model further by only keeping the non-linear terms leading to observed oscillations. Simulations for the dynamic response using the derived model are presented showing excellent agreement with the experimentally observed behaviour. Additionally, deflection shapes are measured and compared with the calculated mode shapes, showing good agreement

Wind tunnel testing of a high aspect ratio wing model

There is much current interest in the development of High Aspect Ratio Wing (HARW) designs for improved aircraft performance. However, there are a lack of relevant data sets available to validate aeroelastic modelling approaches for highly flexible wings. The design and manufacture of a highly flexible 2.4m semi-span wing is described. A series of low speed wind tunnel tests were performed to generate displacement, acceleration, strain gauge, aerodynamic pressure and six component balance measurements for a range of airspeeds and wing root angles of attack. Numerous static and dynamic measurements were made. Preliminary results are shown for the static and dynamic, structural and aerodynamic behaviour over a range of different airspeeds and wing root angles of attack.Peer ReviewedPostprint (published version