imperatori laura (7 Ergebnisse)

Taschenbuch. Zustand: Neu. Druck auf Anfrage Neuware - Printed after ordering - Project Report from the year 2013 in the subject Physics - Acoustics, grade: Alpha, University of Cambridge (Department of Physics), course: Natural Sciences Tripos Part IB, language: English, abstract: In order to test non-linearity, the effects of different transfer functions of an AD633 multiplier in a given electrical circuit were investigated and compared with the theoretical expectations. First of all, the phenomenon of frequency doubling was found to occur when squaring the input voltage. Secondly, the multiplier was reconfigured to give a square-root response. This allowed us to vary the degree of non-linearity by choosing the parameters of input voltage and DC offset such that we could determine which terms in the Taylor expansion of the transfer function were relevant and hence to what degree the circuit behaved non-linearly. For a small, sinusoidal variation about a large DC level, the system was found to be weakly non-linear. For high amplitude and a low DV offset we observed strong non-linearity. Compared to weak non-linearity, we were able to detect the third harmonic as well as the first and the second one. The existence of harmonics was investigated on the PicoScope screen and verified by plotting output amplitude (dBV) versus input amplitude (dBV) and finding the gradient of the slope corresponding to the respective harmonic. Finally, frequency mixing was explored in its broader context by investigating amplitude modulation and demodulation on the same circuit board.

Taschenbuch. Zustand: Neu. Druck auf Anfrage Neuware - Printed after ordering - Scientific Essay from the year 2012 in the subject Physics - Mechanics, , language: English, abstract: In order to test SHM, the behaviour changes of a torsion pendulum due to different damping factors as well as its changes due to applying an external exciter were observed and compared with the theoretical expectations. The quality factor of the same damping state (with a brake current of 6A in the eddy brakes) was calculated using two different approaches and the resulting values were found to be within of each one, as Q1 = 6.0±1.3 and Q2 = 7.5±0.7. The first approach was based on measuring the maximum displacement for each successive oscillation and deducing the slope from the plot of the natural logarithm of the amplitude against the number of oscillations. Differently, the second estimate of Q was obtained under forced oscillation conditions by taking the ratio of the experimentally determined resonance amplitude and the amplitude of natural oscillation.

Taschenbuch. Zustand: Neu. Druck auf Anfrage Neuware - Printed after ordering - Project Report from the year 2012 in the subject Psychology - Learning Psychology, Intelligence Research, grade: A, University of Cambridge (Department of Experimental Psychology), course: Natural Sciences Tripos, language: English, abstract: The Generation-Recognition Theory and the Encoding Specificity Theory that both deliver a process description of human memory were both tested by the Cued Recall & Recognition test - a simplified form of experiments performed by Watkins and Tulving. The Cued Recall & Recognition test was performed on 42 subjects overall and the proportion of words that were recalled, but not recognised, was determined to be 0.27+/-0.19. Two different groups were allocated (unknown to the participants) on the basis of the stimulus sets used (stimulus set 1 or 2) to test the influence of the stimulus sets on obtaining the above results. We verified that our results were not likely to be due simply to the specific stimuli that were used but showing a more general effect given that we found t(40)_{0.05}=1.168 in a two tailed t-test, and, thus, retained H_{0}: ``There is no significant difference in the proportion of words recalled, but not recognised, between the two groups (due to the different stimulus sets used).'' The significant proportion of words being recalled but not recognised contradicts generation-recognition theory, but supports encoding specificity theory, which argues that retrieval is based on a congruence between how information was encoded (or studied) and how it is accessed at retrieval, hence memory is highly context-dependent and episodic in nature.

Taschenbuch. Zustand: Neu. Druck auf Anfrage Neuware - Printed after ordering - Project Report from the year 2013 in the subject Psychology - Methods, grade: A, University of Cambridge (Department of Experimental Psychology), course: Natural Sciences Tripos, language: English, abstract: The principle of adaptive independence regarding middle- and short-wave cones was tested by Stiles 'Two-colour threshold technique'. Using yellow background light, the sensitivity of middle-wave cones was lowered and the shift in higher sensitivity of middle-cones to short-wave cones to blue test flashes was found to occur at a background radiance of 0.03 W/m^2sr .

Taschenbuch. Zustand: Neu. Druck auf Anfrage Neuware - Printed after ordering - Seminar paper from the year 2014 in the subject Psychology - Social Psychology, grade: A, University of Cambridge (Department of Psychology), course: Part IB Experimental Psychology, language: English, abstract: We investigate problem solving by analogy in order to see whether solving a similar, easier problem beforehand aids in deciphering a more complicated one, given that the two problems have a similar (homomorphic) problem state. The two problems that have been used in this experiment are the historic Missionary & Cannibals problem (M&C) as well as its visual representation - referred to as 'Counter-Moving' (CM) in the following. The use of analogy in problem solving requires restructuring the problem in order to create an insight - as can be measured by 'warmth' ratings - in contrast to problem solving based on trial-and-error learning (mostly common in elementary algebra) as proposed by behaviourists such as Thorndike. The restructuring of the problem relies on mapping from a source domain to a target domain. Since there is an infinite number of possible source domains, many humans have difficulies at spontaneous use of analogy and need its relevance to be highlighted. We have shown that the success rate on the counter-moving problem does differ significantly from the success rate on the M&C problem, which implies that the CM problem is conceptually easier to understand. Hence, we could show that solving a similar, easier problem with a homomorphic problem state does indeed increase the success rate of solving a more complicated one later by comparing the success rates between Groups A and B that solved the problems in opposite orders.

Taschenbuch. Zustand: Neu. Druck auf Anfrage Neuware - Printed after ordering - Seminar paper from the year 2014 in the subject Psychology - Learning Psychology, Intelligence Research, grade: A, University of Cambridge (Department of Psychology), course: Natural Sciences Tripos Part IB Experimental Psychology, language: English, abstract: Based on studies by Steele and Aronson that have revealed the phenomenon of stereotype threat in black students, we have tested whether Cambridge undergraduates might suffer from a similar stereotype threat of exceptional intelligence. In this paradigm they would feel the need to perform highly in all kinds of ability tests irrespective of their state anxiety, even if it is known that most people perform worse when experiencing greater anxiety due to a lack of focus. This possibility was investigated by dividing the students - unbeknownst to them - into two groups depending on which kinds of Raven's items - easy or very hard ones - they had to complete immediately prior to a speeded test (the Wechsler Digit Symbol) and a non-speeded test (vocabulary). The different speed conditions were used in order to estimate the effect of state anxiety, since various studies have shown that it might have a negative impact on speeded tests. This experiment has demonstrated that there is no statistically significant difference in the performance on the Wechsler Digit Symbol task as well as on the vocabulary test between the group that was administered the easy Raven's items and the one that was assigned the hard items.

Taschenbuch. Zustand: Neu. Druck auf Anfrage Neuware - Printed after ordering - Seminar paper from the year 2014 in the subject Psychology - Developmental Psychology, grade: A, University of Cambridge (Department of Psychology), course: Part IB Experimental Psychology, language: English, abstract: Our aim was to confirm that vision in adults can be trained to associate certain retinal locations with specific depth arrangements of stimuli, such that presenting a depth-ambiguous stimulus at a certain retinal location would cause it to be perceived to have a specific depth arrangement. Even if Backus et al. have already demonstrated that 'cue-recruitment' is still possible in human adults, i.e. that adults can still learn to associate any arbitrary stimulus feature with depth, we were not able to verify the hypothesis that our ability to perceive depth is not innate and - thus - purely a product of postnatal learning experience, whereby the capacity is still present in human adults. We verified that the 14 subjects could reliably report depth as a group, but they did not perceive, more than would be expected by chance, the same depth arrangement for an ambiguous stimulus at a particular location in the test block as they had for the unambiguous stimuli at that location in the training blocks. Hence, we rejected the first H_{0, training} hypothesis that there is no significant difference in the number of correct and incorrect answers during the training session, and furthermore, retained the second H_{0, test} hypothesis that there is no significant difference between the number of trials, in which a test block was perceived to be same or opposite to the previous training stimuli at the respective same location as in the training trials, since the paired t-test gave rise to t(13)_{0.05}=0.2 , which is well below the expected value for a one-tailed t-test of 1.7.