Solar dynamic modules for Space Station Freedom: The relationship between fine-pointing control and thermal loading of the aperture plate

Dynamic simulations of Space Station Freedom (SSF) configured with solar dynamic (SD) power modules were performed. The structure was subjected to Space Shuttle docking disturbances, while being controlled with a 'natural' vibration and tracking control approach. Three control cases were investigated for the purpose of investigating the relationship between actuator effort, SD pointing, and thermal loading on the receiver aperture plate. Transient, one-dimensional heat transfer analyses were performed to conservatively predict temperatures of the multi-layered receiver aperture plate assembly and thermal stresses in its shield layer. Results indicate that the proposed aperture plate is tolerant of concentrated flux impingement during short-lived structural disturbances. Pointing requirements may be loosened and the requirement control torques lessened from that previously specified. Downsizing and simplifying the joint drive system should result in a considerable savings mass

Analysis of local and global timing and pitch change in ordinary melodies

This paper describes a set of statistical relationships between pitch change structure and timing structures in ordinary melodies. We obtained over 5000 MIDI files for ordinary western melodies, each with a prescribed tempo, so that note timings could be given in seconds. 1): We find that the frequencies of occurrence of different pitch change sizes are stationary: they do not vary during the time-course of a melody, apart from during the first 1 second and the final 1 second. 2): There is an inverse relationship between the mean (absolute) pitch change size in a melody and the mean time interval between successive note onsets: melodies with larger pitch changes tend to be faster.3): The time intervals between successive occurrences of the same pitch change size reflect an active process. 4): For each melody, we construct a function showing the temporal rise and fall in the likelihood of the melody as given by the log of the reciprocal of the frequency of the most recent pitch change. Fourier analysis of these functions shows a regular pattern of coherent variability with a period of between 2 and 6 seconds. Low likelihood portions of a melody are balanced by higher likelihood ones over a time scale of a few seconds

The perception of local and global timing in simple melodies

Local relations refer to adjacent events (such as the time between successive notes in amelody); global relations refer to a continuous succession of local events (such as the rhythmic timing of the complete series of notes in a melody). Tones in a short auditory sequence can have their perceived timing distorted by local pitch relations. The Tau and Kappa timing effects in visual motion stimuli have equivalent auditory pitch motion versions (Shigeno 1993) where the perceived delay from one tone to the next depends on local pitch separation. We report data which show local distortions in the perceived duration of a sequence of 3 tones where the first and last tones have one pitch and the middle tone another pitch. Perceived duration increases with the pitch interval between the middle tone and the others: the larger the pitch interval the longer the perceived duration. We report a range of results which allow us to relate this finding to the relative frequency of the melodic intervals in “vernacular” western tonal music: melodic events that are uncommon (such as a pitch change of a major 7th) are perceived to last longer than identically timed common ones (such as major 2nd). This local effect suggests that there should be an equivalent global effect: large intervals should tend to make melodies sound slower. However, we also report data showing that melodies with frequent large intervals tend to have their perceptual characteristics (such as happiness/sadness) judged as if the melody is faster (not slower) than melodies without large intervals. This shows a discrepancy between local timing and global timing. This set of findings is difficult to reconcile with any unitary additive model of time perception. We will describe an alternative account of time based on the nature of events. Uncommon events happen less frequently (by definition) and therefore the time between uncommon events will normally be longer that the time between common events. In this sense, uncommon events can be said to dilate the perception of time. When events happen more frequently than usual, a melody sounds rushed

It depends what you do in the laboratory

Let us start by stating a strong opinion: psychology can only claim honesty when it makes the effort to relate its own theories and other observations about human behaviour and experience to actual human behaviour and experience in the real world. In this respect, we agree with some of the assumptions the authors make in this article and we share with the authors a sense of frustration that so much effort in cognitive psychology can sometimes yield very little insight beyond the relative sterility shown by some laboratory phenomena

Some robust higher-level percepts for music

We explored a range of higher-level percepts in music. Participants were asked to make two-alternative forced-choice judgments of extracts of instrumental music on various dipole categories, such as happy/sad or male/female. The consistency with which each stimulus was judged on a response category across listeners provides an indication of the extent to which the musical percept can be mapped reliably onto that dimension. High consistency would suggest that the response category is related to one of the natural perceptual dimensions for music. We found very high consistency (90% +) for various response categories normally used as descriptions of people (such as male/female and happy/sad). Other types of response category gave much lower consistency. Perhaps our participants are experts in making fine distinctions in person-related categories for almost any stimulus. We tested this with a control experiment where foodstuffs replaced the musical stimuli. We did not find high agreement for person-related categories. The differences between responses to music and food were statistically highly significant

Development and Training of a Neural Controller for Hind Leg Walking in a Dog Robot

Animals dynamically adapt to varying terrain and small perturbations with remarkable ease. These adaptations arise from complex interactions between the environment and biomechanical and neural components of the animal’s body and nervous system. Research into mammalian locomotion has resulted in several neural and neuro-mechanical models, some of which have been tested in simulation, but few “synthetic nervous systems” have been implemented in physical hardware models of animal systems. One reason is that the implementation into a physical system is not straightforward. For example, it is difficult to make robotic actuators and sensors that model those in the animal. Therefore, even if the sensorimotor circuits were known in great detail, those parameters would not be applicable and new parameter values must be found for the network in the robotic model of the animal. This manuscript demonstrates an automatic method for setting parameter values in a synthetic nervous system composed of non-spiking leaky integrator neuron models. This method works by first using a model of the system to determine required motor neuron activations to produce stable walking. Parameters in the neural system are then tuned systematically such that it produces similar activations to the desired pattern determined using expected sensory feedback. We demonstrate that the developed method successfully produces adaptive locomotion in the rear legs of a dog-like robot actuated by artificial muscles. Furthermore, the results support the validity of current models of mammalian locomotion. This research will serve as a basis for testing more complex locomotion controllers and for testing specific sensory pathways and biomechanical designs. Additionally, the developed method can be used to automatically adapt the neural controller for different mechanical designs such that it could be used to control different robotic systems

Utility of Visual Counts for Determining Efficacy of Management Tools for California Ground Squirrels

Visual counts are frequently used to assess efficacy of management tools for ground squirrels (Marmotini), but the effectiveness of this approach has not been assessed for many ground squirrel species including California ground squirrels (Otospermophilus spp.). As such, we used visual counts of California ground squirrels to determine the efficacy of diphacinone-treated oat groat applications in rangelands in central California, USA, and compared those results to efficacy values derived from the use of radio-collared ground squirrels in the same plots. We also used location data of radio-collared ground squirrels to explore the size of buffer zone needed around census plots to provide an accurate assessment of efficacy when using visual counts. We did not observe a difference in efficacy associated with the 2 monitoring strategies, indicating that visual counts are an effective monitoring tool for ground squirrels. We observed low efficacy in 2 treatment plots, likely due to low usage of those plots by ground squirrels. Increasing the size of buffer zones would increase the usage of treatment areas by the target population and would help to minimize reinvasion by adjacent ground squirrel populations, which could bias efficacy values low. We suggest a minimum of a 61-m buffer surrounding census plots. Increasing to 66 m or more would further benefit efficacy assessments, but increased size of the buffer zone must be balanced with greater costs and regulatory constraints

Efficacy of Rodenticides for Roof Rat and Deer Mouse Control in Orchards

Roof rats and deer mice are occasional pests of orchard crops throughout the world. The application of rodenticides is an effective and practical method for controlling rodent pests and reducing damage. However, a paucity of information exists on the efficacy of rodenticides in orchards for these pest species. To address this gap in knowledge, we first developed an index to measure rodent activity in order to monitor efficacy of rodenticides. We then used this index to test the efficacy of 3 first-generation anticoagulant rodenticide baits to determine their utility for controlling roof rats and deer mice in agricultural orchards. Of the baits tested, the 0.005% diphacinone grain bait was the most effective option for controlling both roof rats and deer mice (average efficacy = 90% and 99%, respectively). The use of elevated bait stations proved effective at providing bait to target species and should substantially limit non-target access to rodenticides

Biomechanical and Sensory Feedback Regularize the Behavior of Different Locomotor Central Pattern Generators

This work presents an in-depth numerical investigation into a hypothesized two-layer central pattern generator (CPG) that controls mammalian walking and how different parameter choices might affect the stepping of a simulated neuromechanical model. Particular attention is paid to the functional role of features that have not received a great deal of attention in previous work: the weak cross-excitatory connectivity within the rhythm generator and the synapse strength between the two layers. Sensitivity evaluations of deafferented CPG models and the combined neuromechanical model are performed. Locomotion frequency is increased in two different ways for both models to investigate whether the model’s stability can be predicted by trends in the CPG’s phase response curves (PRCs). Our results show that the weak cross-excitatory connection can make the CPG more sensitive to perturbations and that increasing the synaptic strength between the two layers results in a trade-off between forced phase locking and the amount of phase delay that can exist between the two layers. Additionally, although the models exhibit these differences in behavior when disconnected from the biomechanical model, these differences seem to disappear with the full neuromechanical model and result in similar behavior despite a variety of parameter combinations. This indicates that the neural variables do not have to be fixed precisely for stable walking; the biomechanical entrainment and sensory feedback may cancel out the strengths of excitatory connectivity in the neural circuit and play a critical role in shaping locomotor behavior. Our results support the importance of including biomechanical models in the development of computational neuroscience models that control mammalian locomotion