316 research outputs found
Ergonomics in machine design : a case-study of the self-propelled combine harvester
No full text7. 1. INTRODUCTIONMechanization not only changes the character and structure of labour in agriculture and industry, but also influences the nature of the work load. Instead of delivering energy, the main issue now is the perception and processing of information, as well as controlling and regulating the work being done by machines. More and more the accent is shifting to tasks which appeal to the capacity of man to process information.Supplying the requirements for increased capacity is possible by increasing the ground speed and/or the working width, which, however, involves higher information speed, more actions for operation per time unit and a higher operator's work load. Human beings should not adapt themselves to the machine and - as a consequence of too high a load - will hazard occupational diseases and reduced performance.By means of principles, parameters, procedures and criteria from various disciplines - anthropometry, perception, selection and action - ergonomics can contribute to an optimum man - task system with a high capacity and a favourable operator's load.This study deals with the ergonomic system-analysis of the operation of a self- propelled combine harvester. The operator of this machine regulates the movement - direction and speed -, the mowing and threshing, the separation of kernel and straw, as well as the delivery of the product. Based upon the information obtained from crop, terrain, plot and machine the operator has to decide on such an adjustment of the machine, which results in a process with a high capacity and a high quality of work.7.2. ANTHROPOMETRYThe characteristics of the human body determine the location and displacement of the operating controls, as well as the forces to be exerted, the nature and frequency of movements. Based upon the relevant measurements and motions of the human body, the anthropometric data are given for designing an optimum work- space lay-out of a combine harvester.1. Lay-out studiesTo determine the location and displacement of the controls, as well as the forces to be exerted, and the location of the foot-board and cutterbar, special measuring equipment and methods have been developed.The work-space lay-out - specific for each machine - appeared to differ considerably. It is recommendable, that frequently used controls are located close to each other and within the normal area.The forces needed for steering are very low, because of the application of power steering. The forces needed for operating the clutch and the brake-Pedal are too high for the older machines; for the newer combines they meet the requirements.2. FrequencyThe frequency with which different operations and movements have to be carried out, determines mainly the operator's work load. The data, collected in measuring the operation frequency, indicate the priority in the lay-out of controls.The studies show, that the header height, reel position and ground speed control are most important. The location and displacement of these controls deserve priority in the design of the work-space lay-out.The movements of the steering wheel only have a correcting character.3. M.T.M.-analysisBased upon the results of the lay-out studies and the frequency-analysis, the operating element time has been calculated by means of M.T.M.; these timevalues can be used to obtain reliable data of the ergonomic quality of the lay-out of a certain work-space.The study shows, that there are great differences between the various machines; a small modification in the work-space lay-out leads to a favourable change in the operating element time. A development in the direction of fingertip control - i.e. header height, reel position and ground speed control grouped together - is desirable.7.3. PERCEPTIONThe perception of information, that a worker receives from work-space and environment, takes place via the senses, which are sensitive to specific impulses. The reaction to the information depends upon the sense organ that is stimulated, the strength of the stimulus and the place where the stimulus arrives.1. SightThe perception of visual information depends upon the object, the environment and the distance between the eye and the object.For combining it is necessary to obtain information from the feed table auger just in front of the conveyor chain and of the separation from the previously cut swath. On the machines examined the visual angle, as well as the horizontal distance between the eye and the cutterbar, are favourable in the horizontal plane. In the vertical plane the view angle is extremely unfavourable; besides, the distance between the eye and the cutterbar is too long, which is caused by the large vertical distance.Improvement of the visibility is possible by reduction of the view angle and the vertical distance. The operator's platform must be brought closer to the field. An eccentric location of the operator's platform offers favourable possibilities, since the platform can be located next to the conveyor chain.2. HearingHearing ensures mutual communication between man, machine and environment. Depending on frequency, sound pressure level and duration of the exposure, sound has an annoying or a damaging effect.By the functioning of the engine and other parts of the machine, in particular: the threshing mechanism, the operators of combines are submitted to sound. Measured at the operator's ear, the sound pressure levels of the machines examined are too high, whilst the presence of a cabin does not lead to an important decline of the sound pressure level. Moreover, the ground speed during combining does not affect the sound pressure level.The most common method of solving the sound problem is the enclosure of the source to reduce the sound pressure level to bearable levels.3. Scent and tasteFrom an ergonomic point of view scent and taste are less important, because only a small number of actions appeals specifically to these senses. Attention must be paid to the dust in the air around an operator of a combine.The dust concentration in the air around operators of the machines examined is too high; with respect to the duration of the harvesting period the possibility of developing silicosis must be considered to be low. On a machine without cabin the dust concentration is considerably higher than on a machine with cabin; during harvesting barley less dust is circulating around the operator than during harvesting wheat.Protection of the operator of a combine against dust is possible by ventilation (blowing away or sucking off the particles) and personal protective equipment. The ideal concept is the enclosure of the operator in a cabin with a small overpressure, so that particles cannot penetrate into the work-space.4. FeelingBy uneveness of terrain and road surface, the profile of the tyres and the functioning of the engine and other parts of the machine, the operators of machinery are submitted to mechanical vibrations, which adversely affect their health and performance. The effect and impact of vibrations varies with the frequency, as the human body is most sensitive to mechanical vibrations within the frequency range from 2 Hz to 6 Hz. It is necessary, that the curve K = 4 of the VD1- Recommendation is not exceeded in designing the work-space of farm machinery.The intensity of mechanical vibrations on combine harvesters is low, whilst the movements in the vertical direction are more numerous than in the other directions. Combining at different ground speeds appears to affect hardly the intensity; with greater working width the intensity is slightly smaller. When driving on the road with increasing ground speeds there appears an increasing intensity, which is lower than during combining. The spectral distribution indicates the existence of specific frequency ranges, which are explicable from the machine.At present, the most obvious way to reduce ride vibration is to fit a correctly designed suspension seat. The benefit of a good suspension seat is limited by the increasing movements between the operator and the controls; to eliminate this the vibrations of the whole vehicle or the whole of the operator's work-space should be reduced. A suspended enclosed cabin - in which controls, seat and operator move simultaneously - is an approach, which combines the need for improving ride with greater protection from sound and dust.Since machines, performing functions of perception, do not exist or are very rare, the designer of a man-task system must take into account the attainments of the investigations regarding perception. For the combine this means primarily an adequate presentation of the relevant information; by improving the visibility of the cutterbar (reduction of the view angle and the vertical distance) this can be realized. Besides, the redundant and non-relevant information - sound, dust and mechanical vibrations - has to be eliminated; the suspended cabin - in which the controls, the seat and the operator move simultaneously - is an approach, which combines the need for improving ride with greater protection from sound and dust.7.4. SELECTIONThe transport of data from the stimulated sense organs ('input') to the effectors ('output') is not simply and solely transport. The data are processed, from the various possibilities the right answer is chosen ('choice') and transformed into action.1. TheoryIn task performance the number of directed switches from input to output determines information processing and mental load, because all signals make use of 'a single channel decision mechanism' with a limited capacity. Generally, a value of two to three bits per second is assumed to be the limit for adequate information processing.For the assessment of mental load a well-functioning parameter is not yet available; most can be expected of the method with dual tasks and the heart rate.2. Indoor experimentsFor studying a man-task system under controlled conditions and to obtain information regarding the ergonomic qualities of the work-space lay-out of a certain machine, a simulator is built.The studies led to the following conclusions:a. In simulating the operation of a combine harvester the performance and the load depend upon the experimental distraction and the anthropometric qualities of the work-space lay-out. The steering accuracy detiorates and the load increases as a function of the number of signals per minute in the secondary task. There is a significant difference between the machines, which increases as the experimental distraction increases.b. By executing an identical series of information a learning curve appears; the performance increases and the load decreases as a function of the number of cycles. The appearance of the learning curve is disturbed by different series of information in an experiment. There is a significant difference between the machines.In simulating the operation of a combine harvester, the performance and the load depend upon the experimental distraction (the number of signals per minute in the secondary task and the series of information in an experiment) and the anthropometric qualities of the work-space lay-out of the machine. The results of the indoor experiments confirm the statements - endorsed completely by the results of the M.T.M.-analysis -, that subjects are more quickly familiar with one machine than with another, which causes a more efficient performance.The conclusion can be made, that the performance and the load are primarily determined by the work-space lay-out.7.5. ACTIONThe choice of the decision mechanism is transported to the effectors and transformed into voluntary muscle movements, which are necessary for the output or performance of a man - task system.1. TheoryThe muscle movements demand energy and this leads to the physical load of man, whose working capacity is limited. Besides, the mechanical effect of human labour is very slight. An energy consumption of 20 kJ (= 4,8 kcal) per minute, including a basal metabolic rate of about 4,2 kJ (= 1 kcal) per minute, has been accepted as the maximum consistent level, that an adult man should be expected to expend.For the assessment of physical load well-functioning parameters are available. In all kinds of tasks, even over a long period of time, the heart rate can be faultlessly registered.2. Field experimentsFor collecting data about the character and extent of loading components during combining, as well as the influence they have on the output of the system, field experiments have been carried out.The studies led to the following conclusions:a. During the operation of a combine harvester the performance and the load depend upon the machine - in particular: the operator's platform-, the stubble height, the ground speed, the working width and the crop. There is a significant difference between the operator's platforms, which increases as the ground speed increases. The interaction between ground speed and working width, representing capacity, is significant; realizing a certain level of capacity, it is preferable to work at a low ground speed combined with a greater working width.b. Using an automatic header height control system the operation frequency and the load decrease. The advantage of an automatic system becomes greater when working at higher ground speeds.The results of the field experiments endorse completely the results of the anthropometric studies and the indoor experiments. There are differences between the machines; at an increasing information speed - indoor: increasing experimental distraction; field: increasing ground speed - the differences between the machines become greater.The conclusion can be repeated, that the performance and the load are primarily determined by the work-space lay-out.7.6. DISCUSSIONHuman beings should not adapt themselves to the machine and - as a consequence of too high a load - will hazard occupational diseases and reduced performance. By means of principles, parameters, procedures and criteria from various disciplines - Anthropometry (Chapter 2), Perception (Chapter 3), Selection (Chapter 4) and Action (Chapter 5) - the ergonomic factors, influencing the output or performance in operating a self-propelled combine harvester, have been studied by means of lay-out studies, indoor and field experiments. Based upon the results of these studies the conclusion can be made, that the performance and the load in a man-task system are primarily determined by the workspace lay-out. Recommendations for the ideal concept of the operator's platform of the self-propelled combine harvester are given (Chapter 6).Supplying the requirements for an increase of capacity it is necessary, that the designer of a self-propelled combine harvester pays attention to an adequate processing of the increasing information speed. This is possible by using machines with an optimum work-space lay-out and eliminating of redundant and non-relevant information. Moreover, the introduction of automation, in which many processes - combine: moving, mowing, threshing, cleaning and maintenance - are executed and corrected without human interference, offers favourable advantages.In the near future the 'supervisor of harvesting' has to settle - based upon the conditions of crop, terrain and climate - the norm and the tolerance of the whole process. Next to it, the supervisor has to control - sitting at home, in front of a correctly designed console - the processes and, if necessary, has to re-adjust by means of remote-control
Mobile air quality studies (MAQS) in inner cities: particulate matter PM10 levels related to different vehicle driving modes and integration of data into a geographical information program
Get PDFABSTRACT: BACKGROUND: Particulate matter (PM) is assumed to exert a major burden on public health. Most studies that address levels of PM use stationary measure systems. By contrast, only few studies measure PM concentrations under mobile conditions to analyze individual exposure situations.
METHODS: By combining spatial-temporal analysis with a novel vehicle-mounted sensor system, the present Mobile Air Quality Study (MAQS) aimed to analyse effects of different driving conditions in a convertible vehicle. PM10 was continuously monitored in a convertible car, driven with roof open, roof closed, but windows open, or windows closed.
RESULTS: PM10 values inside the car were nearly always higher with open roof than with roof and windows closed, whereas no difference was seen with open or closed windows. During the day PM10 values varied with high values before noon, and occasional high median values or standard deviation values due to individual factors. Vehicle speed in itself did not influence the mean value of PM10; however, at traffic speed (10 -- 50 km/h) the standard deviation was large. No systematic difference was seen between PM10 values in stationary and mobile cars, nor was any PM10 difference observed between driving within or outside an environmental (low emission) zone.
CONCLUSIONS: he present study has shown the feasibility of mobile PM analysis in vehicles. Individual exposure of the occupants varies depending on factors like time of day as well as ventilation of the car; other specific factors are clearly identifiably and may relate to specific PM10 sources. This system may be used to monitor individual exposure ranges and provide recommendations for preventive measurements. Although differences in PM10 levels were found under certain ventilation conditions, these differences likely are not of concern for the safety and health of passengers
Personalities in female domesticated pigs: behavioural and physiological indications
Get PDFThe inconclusive evidence so far on the existence of distinct personality types in domesticated pigs, led us to perform the present experiment. A total of 128 gilts from 31 sows were systematically studied from birth to slaughter in two identical trials. Intra-test consistency in individual behavioural andror physiological reactions was studied in three different tests. We were not able to show consistencies in reactions of gilts over time to a backtest (at 2–4 days and 4 weeks of age) and to a novel environment test (at 10 and 24 weeks of age). Individual aggression, however, as measured in a group-feeding competition test in stable groups (at 10 and 24 weeks of age), proved to be highly consistent. Explanations for these discrepancies in intra-test consistencies are critically discussed. Inter-test consistencies were determined by relating the individual reactions of gilts to the backtest to various characteristics and responses to tests at a later age. The highest correlations were found when resistance in the first backtest was involved. No evidence was found for the existence of specific isolated categories of animals with respect to this resistance. For further analysis, extreme responding gilts in the first backtest (roughly the top and bottom 25% of the distribution) were classified as low resistant (LR; <3 escape attempts; n=31) or high resistant (HR; >4 escape attempts; n=45). By comparisons of mean responses of LR and HR gilts within groups, we have established a relationship between the backtest and several other variables. Behaviourally, the HR gilts showed more aggression in the group-feeding competition tests. Also, in the competition for the most productive teats at the anterior, a predominant position of HR piglets at this site was observed during the suckling period. The latter piglets also gained more weight during this period than LR ones. Compared to HR pigs, in the first novel environment test LR pigs hesitated longer to leave their home pens and to contact a human, but no difference in their locomotory behaviour was observed. Contrasts between LR and HR pigs in the second novel environment test were reduced or absent. Physiologically, when compared to HR gilts, LR ones had a higher reactivity of the hypothalamic–pituitary–adrenocortical (HPA) system. This was shown by higher cortisol responses to the first novel environment test, to routine weighing at 25 weeks of age, and to administration of a high dose of ACTH. It is discussed that these findings for LR and HR gilts, may provide support for the existence of behavioural and physiological responses in pigs, resembling those of proactive and reactive rodents.
Behavioural and physiological consequences of acute social defeat in growing gilts: effects of the social environment
Get PDFEndocrine, behavioural and immunologic processes, together with body growth, were evaluated in gilts that were defeated at 10 weeks of age in resident-intruder tests. Immediately after defeat, gilts were either separated from or reunited with a familiar conspecific (litter-mate; always a barrow). Gilts were assigned to one of four treatments: (a) DI: defeat, followed by isolation (separation from original litter-mate; n=8); (b) I: no defeat, isolation (control group; n=9); (c) DP; defeat, followed by pair-housing (reunion with original litter-mate; n=8); and (d) P: no defeat, pair-housing (control group; n=8). The following general conclusions were derived: (1) social defeat caused pronounced short-term elevations in hypothalamic-pituitary-adrenal (HPA) and sympathetic-adrenal medullary activities, and of prolactin levels. Moreover, as soon as 1 h after defeat, percentages of blood lymphocytes and neutrophilic granulocytes were, respectively, decreased and increased; (2) social defeat had some long-lasting influence on behaviour and physiology, but isolation predominantly determined responses in the longer term. Defeat, as well as isolation, resulted in increased cardiovascular activities compared to P controls, as observed in a novel object test (NOT: +7 days) and an aversion test (AVT: +14 days). Moreover, defeated as well as isolated gilts did not habituate to a repeated novel environment test (NET: -7, +2 and +7 days) in terms of frequencies of vocalising, whereas P controls did. Isolation, through the separation from any other pig, was responsible for the other observed long-term characteristics, which developed progressively. Isolated gilts showed high mobilities and high cortisol responses in the repeated NET (+7 days), not being habituated. This contrasted the reactions of pair-housed gilts, which were much reduced. In addition to their high cardiovascular activities in the NOT and the AVT, isolated gilts also displayed higher heart rates in the repeated NET and during human presence following the NOT, compared to pair-housed gilts. Finally, isolated gilts were more inhibited to approach a novel object (in the NOT) than pair-housed pigs; and (3) stress responses of defeated gilts were modulated by the subsequent social environment. Stimulation of the HPA-axis (plasma- and salivary cortisol) was prolonged in those defeated gilts which were isolated (observed in the first hour). Changes in leucocyte subsets were still observed after 3 days in DI, but were `normalised' within 1 day in DP gilts. Two days after defeat, habituation to the repeated NET in terms of mobility and salivary cortisol responses occurred in control and DP gilts, but not in DI gilts. We argue that these effects of the social environment shortly after defeat were related to a stress-reducing effect of a stable social relationship, i.e. social support.
Estudo do processo e das ferramentas de reprojeto de produtos industriais, como vantagem competitiva e estrategia de melhoria constante
Get PDFDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro TecnologicoA presente dissertação apresenta um estudo do processo de reprojeto de produtos industriais, como vantagem competitiva e estratégica para a melhoria constante dos produtos. Define-se o termo de reprojeto de produtos industriais e se mostram suas características, princípios e conceitos gerais. Posteriormente se identificam as diferentes necessidades de reprojeto e os fatores determinantes que levam a indústria a reprojetar um produto. Estas informações são utilizadas para estabelecer as especificações de reprojeto, conforme a ferramenta da casa da qualidade. É abstraída a função global do produto em estudo e são geradas as soluções de melhoria no produto através de métodos de criatividade, utilizados na fase conceitual. As estratégias de reprojeto para o ciclo de vida do produto auxiliam na avaliação da concepção inicial, para eliminar os pontos fracos e melhorar o produto como parte do reprojeto detalhado. Por último se pretende ilustrar o processo e os métodos utilizados, através de um estudo de caso prático
Adaptation to social isolation Acute and long-term stress responses of growing gilts with different coping characteristics
Get PDFThe present experiment studied the acute and long-term stress responses of reactive and proactive prepubertal gilts to social isolation. Gilts with either reactive or proactive features were identified according to behavioral resistance in a backtest at a young age (2–4 days), respectively being low (LR) and high resistant (HR) in this test. At 7 weeks of age, 12 gilts of each type were socially isolated. Initially, isolation was stressful for both types of gilts, as shown by increased cortisol concentrations and decreased body temperatures. Moreover, both types reacted with increases in exploration and vocalizations. Stress responses to isolation, however, differed in magnitude and/or duration between LR and HR gilts, which was in line with expected reaction patterns on the basis of preferred ways of coping. The cortisol response to isolation was higher in LR gilts, and they generally showed more explorative behavior. HR gilts seemed to be more engaged in walking/running behavior in the first hour after isolation, they generally vocalized more and their noradrenaline excretion in urine was higher at 3 weeks after the start of isolation. Several responses to isolation in the longer term pointed to a prolonged higher general state of stress of HR gilts. Body temperature in HR gilts, for instance, did not recover during 3 weeks of isolation, but values returned to ‘‘normal’’ within 1 day in LR gilts. At 1 week of isolation, relatively high parasympathetic responsivity to novelty was observed in HR gilts, probably due to stress-related high sympathetic reactivity. A shift in percentages of leucocyte subsets, typically occurring under conditions of stress, only developed in HR gilts during isolation. Finally, gastric ulceration was found in one HR gilt, but did not occur in LR gilts. To conclude, LR and HR gilts differed in their strategies to adapt to social isolation, and especially for HR gilts, this procedure seemed to become a chronic stressor.
Increasing weaning age of piglets from 4 to 7 weeks reduces stress, increases post-weaning feed intake but does not improve intestinal functionality
No full textThis study tested the hypothesis that late weaning and the availability of creep feed during the suckling period compared with early weaning, improves feed intake, decreases stress and improves the integrity of the intestinal tract. In this study with 160 piglets of 16 litters, late weaning at 7 weeks of age was compared with early weaning at 4 weeks, with or without creep feeding during the suckling period, on post-weaning feed intake, plasma cortisol (as an indicator of stress) and plasma intestinal fatty acid binding protein (I-FABP; a marker for mild intestinal injury) concentrations, intestinal morphology, intestinal (macro)molecular permeability and intestinal fluid absorption as indicators of small intestinal integrity. Post-weaning feed intake was similar in piglets weaned at 4 weeks and offered creep feed or not, but higher (P <0.001) in piglets weaned at 7 weeks with a higher (P <0.05) intake for piglets offered creep feed compared with piglets from whom creep feed was witheld. Plasma cortisol response at the day of weaning was lower in piglets weaned at 7 weeks compared with piglets weaned at 4 weeks, and creep feed did not affect cortisol concentration. Plasma I-FABP concentration was not affected by the age of weaning and creep feeding. Intestinal (macro)molecular permeability was not affected by the age of weaning and creep feeding. Both in uninfected and enterotoxigenic Escherichia coli-infected small intestinal segments net fluid absorption was not affected by the age of weaning or creep feeding. Creep feeding, but not the age of weaning, resulted in higher villi and increased crypt depth. In conclusion, weaning at 7 weeks of age in combination with creep feeding improves post-weaning feed intake and reduces weaning stress but does not improve functional characteristics of the small intestinal mucos
Mobile Air Quality Studies (MAQS): An international project
Get PDFDue to an increasing awareness of the potential hazardousness of air pollutants, new laws, rules and guidelines have recently been implemented globally. In this respect, numerous studies have addressed traffic-related exposure to particulate matter using stationary technology so far. By contrast, only few studies used the advanced technology of mobile exposure analysis. The Mobile Air Quality Study (MAQS) addresses the issue of air pollutant exposure by combining advanced high-granularity spatial-temporal analysis with vehicle-mounted, person-mounted and roadside sensors. The MAQS-platform will be used by international collaborators in order 1) to assess air pollutant exposure in relation to road structure, 2) to assess air pollutant exposure in relation to traffic density, 3) to assess air pollutant exposure in relation to weather conditions, 4) to compare exposure within vehicles between front and back seat (children) positions, and 5) to evaluate "traffic zone"-exposure in relation to non-"traffic zone"-exposure. Primarily, the MAQS-platform will focus on particulate matter. With the establishment of advanced mobile analysis tools, it is planed to extend the analysis to other pollutants including NO2, SO2, nanoparticles and ozone
Mudanças de temperatura corporal induzidas por estresse em pombos (Columba Livia)
Get PDFDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Biológicas, Programa de Pós-Graduação em Neurociências, Florianópolis, 2014Mudanças na Temperatura corporal (Tc) são consequências fisiológicas significativas induzidas por estímulos estressores em mamíferos e aves. Pombos (Columba Livia) vivem em ambientes urbanos potencialmente estressores e são comumente usados para estudos neurocomportamentais; entretanto, as respostas térmicas ao estresse em pombos são pouco conhecidas. Descrevemos alterações térmicas (intra-celomática), a partir de registros telemétricos, dada a uma variedade de estímulos potencialmente estressores, incluindo transferência a uma nova gaiola, que conduz a um isolamento visual entre os membros da mesma espécie; a presença do experimentador; a manipulação suave; injeção fictícia (i.p.); e contenção para indução à imobilidade tônica (IT). A transferência à gaiola experimental (GExp) provocou uma curta hipertermia (10-20 min), seguida por uma diminuição longa e substancial na Tc, retornando a valores basais cerca de 150 min após a transferência. Depois de cerca de 2 horas na GExp, os outros estímulos potencialmente estressantes evocaram apenas hipertermia marginalmente significativa no teste de IT e entrada do experimentador ou hipotermia na resposta de injeção fictícia. Estímulos oferecidos 26 horas após transferência induziram aumentos intensos na Tc nos testes de entrada do experimentador e manipulação suave ou resposta hipotérmica no teste de injeção fictícia. Essas mudanças na Tc não parecem estar relacionadas com modificações na atividade geral do animal (medidas de dados actimétricos registrados por telemetria). Repetidos testes não conseguiram afetar as respostas hipotérmicas da transferência à GExp, mesmo depois de 9 ensaios com 1 ou 8 dias de intervalo entre eles, o que sugere que o isolamento social (visual) entre os membros da mesma espécie pode ser um estímulo forte e dificilmente controlável nessa espécie. Esses dados indicam que mudanças de temperatura induzidas por estresse podem ser um parâmetro fisiológico consistente e confiável de estresse, mas que também podem mostrar atributos do tipo, direção e espécie específicos para cada estímulo estressor.Abstract: Changes in body temperature are significant physiological consequences of stressful stimuli in mammals and birds. Pigeons (Columba livia) prosper in (potentially) stressful urban environments and are common subjects in neurobehavioral studies; however, the thermal responses to stress stimuli by pigeons are poorly known. Here, we describe acute changes in the telemetrically recorded celomatic (core) temperature (Tc) in pigeons given a variety of potentially stressful stimuli, including transfer to a novel cage (ExC) leading to visual isolation from conspecifics, the presence of the experimenter (ExpR), gentle handling (H), sham intracelomatic injections (SI), and the induction of the tonic immobility (TI) response. Transfer to the ExC cage provoked short-lived hyperthermia (10-20 min) followed by a long-lasting and substantial decrease in Tc, which returned to baseline levels 150 min after the start of the test. After a 2-hour stay in the ExC, the other potentially stressful stimuli evoked only weak, marginally significant hyperthermic (ExpR, IT) or hypothermic (SI) responses. Stimuli delivered 26 h after transfer to the ExC induced definite and intense increases in Tc (ExpR, H) or hypothermic responses (SI). These Tc changes appear to be unrelated to modifications in general activity (as measured via telemetrically recorded actimetric data). Repeated testing failed to affect the hypothermic responses to the transference to the ExC, even after nine trials and at 1- or 8-day intervals, suggesting that the social (visual) isolation from conspecifics may be a strong and poorly controllable stimulus in this species. The present data indicated that stress-induced changes in Tc may be a consistent and reliable physiological parameter of stress but that they may also show stressor type-, direction- and species-specific attributes
Low cost integration of Electric Power-Assisted Steering (EPAS) with Enhanced Stability Program (ESP)
Get PDFVehicle Dynamics Control (VDC) systems (also known as Active Chassis
systems) are mechatronic systems developed for improving vehicle comfort,
handling and/or stability. Traditionally, most of these systems have been
individually developed and manufactured by various suppliers and utilised by
automotive manufacturers. These decentralised control systems usually
improve one aspect of vehicle performance and in some cases even worsen
some other features of the vehicle.
Although the benefit of the stand-alone VDC systems has been proven,
however, by increasing the number of the active systems in vehicles, the
importance of controlling them in a coordinated and integrated manner to
reduce the system complexity, eliminate the possible conflicts as well as
expand the system operational envelope, has become predominant. The
subject of Integrated Vehicle Dynamics Control (IVDC) for improving the
overall vehicle performance in the existence of several VDC active systems has
recently become the topic of many research and development activities in both
academia and industries
Several approaches have been proposed for integration of vehicle control
systems, which range from the simple and obvious solution of networking the
sensors, actuators and processors signals through different protocols like CAN
or FlexRay, to some sort of complicated multi-layered, multi-variable control
architectures. In fact, development of an integrated control system is a
challenging multidisciplinary task and should be able to reduce the complexity,
increase the flexibility and improve the overall performance of the vehicle.
The aim of this thesis is to develop a low-cost control scheme for integration of
Electric Power-Assisted Steering (EPAS) system with Enhanced Stability
Program (ESP) system to improve driver comfort as well as vehicle safety. In
this dissertation, a systematic approach toward a modular, flexible and
reconfigurable control architecture for integrated vehicle dynamics control
systems is proposed which can be implemented in real time environment with
low computational cost. The proposed control architecture, so named
“Integrated Vehicle Control System (IVCS)”, is customised for integration of
EPAS and ESP control systems.
IVCS architecture consists of three cascade control loops, including high-level
vehicle control, low-level (steering torque and brake slip) control and smart
actuator (EPAS and EHB) control systems. The controllers are designed based
on Youla parameterisation (closed-loop shaping) method. A fast, adaptive and
reconfigurable control allocation scheme is proposed to coordinate the control
of EPAS and ESP systems. An integrated ESP & ESP HiL/RCP system
including the real EPAS and Electro Hydraulic Brake (EHB) smart actuators
integrated with a virtual vehicle model (using CarMaker/HiL®) with driver in the
loop capability is designed and utilised as a rapid control development platform
to verify and validate the developed control systems in real time environment.
Integrated Vehicle Dynamic Control is one of the most promising and
challenging research and development topics. A general architecture and
control logic of the IVDC system based on a modular and reconfigurable control
allocation scheme for redundant systems is presented in this research. The
proposed fault tolerant configuration is applicable for not only integrated control
of EPAS and ESP system but also for integration of other types of the vehicle
active systems which could be the subject of future works.PhD in Power and Propulsio
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