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Evaluates the applicability of ultrasonic sensors in a welding environment and reports on experimental measurements carried out with a sensory head containing ultrasonic transducers with different frequencies. Analyses the effects on the sensors of factors such as noise, temperature and shielding gas flow and concludes by suggesting appropriate protective measures for the sensors for them to operate effectively in a welding environment.

The pulse‐echo method used for the measurement of distances is based on the determination of the fly‐time, employed by the wave (a pulse or a short train) to travel from the sensor to the object and back. It is easy to measure with accuracy the precise moment of the emission, but determining the precise moment of the arrival of the echo is somewhat more complex.

Analyses the effects of temperature on the behaviour of ultrasonic sensors applied to object recognition. Describes the measurement system employed, the environmental considerations of ultrasonic sensors and looks at the most commonly used parameters to analyse the echo form in the recognition process. Evaluates the performance of the parametric model of the ultrasonic echo signal with a comparative study of different ultrasonic transducers.

This work presents a robot prototype designed and built for a new aided fruit‐harvesting strategy in highly unstructured environments, involving human‐machine task distribution. The operator drives the robotic harvester and performs the detection of fruits by means of a laser range‐finder, the computer performs the precise location of the fruits, computes adequate picking sequences and controls the motion of all the mechanical components (picking arm and gripper‐cutter). Throughout this work, the specific design of every module of the robotized fruit harvester is presented. The harvester has been built and laboratory tests with artificial trees were conducted to check range‐finder’s localization accuracy and dependence on external conditions, harvesting arm’s velocity, positioning accuracy and repeatability; and gripper‐cutter performance. Results show excellent range‐finder and harvesting arm operation, while a bottleneck is detected in gripper‐cutter performance. Some figures showing overall performance are given.

Outlines research work on the control of flexible single‐link robot arms in which the link is modelled as a beam and the end‐point position is controlled by measuring that position and using that measurement as a basis for applying a torque to the link joint. A position sensor device [PSD] is used as the measuring device. Describes how the measurement is taken and explains the measurement circuit and how the links are analyzed. Concludes that the simplicity of the general configuration of the photosensor system and the nature of the direct data obtained allows it to be used in a wide range of applications.

The purpose of this study is to examine the biophysical and socioeconomic impacts of climate change on maize production and food security in sub-Saharan Africa (SSA) using adapted improved maize varieties and well-calibrated and validated bioeconomic models.

Using the past climate (1950-2000) as a baseline, the study estimated the biophysical impacts of climate change in 2050 (2040-2069) and 2080 (2070-2099) under the A1B emission scenario and three nitrogen levels, and the socioeconomic impacts in 2050.

Climate change will affect maize yields across SSA in 2050 and 2080, and the extent of the impact at a given period will vary considerably between input levels, regions and maize mega environments (MMEs). Greater relative yield reductions may occur under medium and high-input intensification than under low intensification, in Western and Southern Africa than in Eastern and Central Africa and in lowland and dry mid-altitude than in highland and wet mid-altitude MMEs. Climate change may worsen food insecurity in SSA in 2050 through its negative impact on maize consumption and reduction in daily calorie intake. However, international trade has the potential to offset some of the negative impacts.

The study calibrated and applied bioeconomic models to estimate the biophysical and socioeconomic impact of climate change on maize production at fine resolution. The results could be used as a baseline to evaluate measures that will be applied to adapt maize to the future climate in SSA.

The purpose of this paper is to better understand how consumers perceive and process danger in American football and why they continue to enjoy watching the sport given society’s increased understanding of the danger to the athletes.

Two studies, one lab study with eye-tracking (N = 152) and one survey study (N = 444), were conducted. Study 1 examines how the perception of danger associated with football mediates the relationship between exposure to violent or nonviolent video clips and enjoyment of watching video clips. Study 2 examines how device type and screen resolution influence perceptions of danger associated with football.

Findings support the role that perceived danger plays in sport viewing enjoyment. The results are in keeping with reversal theory where individuals have a protective frame that allows them to experience negative emotions (e.g. anxiety) as positive (e.g. excitement). The research also shows that for larger devices, the perception of danger associated with football is significantly influenced by high resolution.

The work, through considering the way consumers experience sport, questions societal tolerance for entertainment that is dangerous to sport participants.

The findings of this work corroborate past research that has found that consumers of sport do enjoy danger for athletes in their viewing experience. Reversal theory is utilized to explain how negative emotions are experienced as positive. The work extends past findings by showing that the characteristics of the device used (large size and high resolution) during sport viewing influence perceptions of danger.

This paper presents some aspects of the research activities on sensors for robots, developed in the Instituto de Automatica Industrial (IAI) during the last years. The demand for greater precision in the measurement of distances using US techniques, makes it necessary to compensate for alterations in the sound‐speed in the interposed medium due to temperature. In this paper we will describe a method for calculating this correction in order that no other external sensor be necessary. The method is based on the resonance‐frequency variation of the piezoelectric elements with temperature. The accuracy reached with this correction is higher than normally would be needed in robotics applications.

To construct a commercial agricultural manipulation for fruit picking and handling without human intervention.

Describes a research activity involving a totally autonomous robot for fruit picking and handling crates.

Picking time for the robotic fruit picker at 8.7 s per orange is longer than the evaluated cited time of 6 s per orange.

The final system, recently tested, has not yet achieved a level of productivity capable of replacing human pickers. Further mechanical modifications and more robust and adaptive algorithms are needed to achieve a stronger robot system.

Experimental results and new simulations look very promising.

Will help to limit costs and guarantee a high degree of reliability.

Automatic target recognition in agricultural harvesting robots is characterized by low detection rates and high false alarm rates due to the unstructured nature of both the environment and the objects. To improve detection human‐robot collaboration levels were defined and implemented. The collaboration level is defined as the level of system autonomy or the level at which the human operator (HO) interacts with the system. Experimental results on images taken in the field indicate that collaboration of HO and robot increases detection and reduces the time required for detection.