The effects of computer-assisted keyboard technology and MIDI accompaniments on group piano students' performance accuracy and attitudes.

Recommendations from the results include using CAI such as the Guide Mode to help group piano students improve in pitch accuracy during the early stages of learning new repertoire. After students feel comfortable with the pitches, practicing with MIDI accompaniments but without the Guide Mode may assist in the development of rhythmic continuity. However, teachers should not assume that the technology is an automatic way of improving piano performance. More time to practice with the technology outside of the classroom setting may be needed to observe any longer term effects on students' performance.Perceptions of MIDI accompaniments and the Guide Mode's effectiveness in helping students improve performance accuracy were generally positive. In open-ended responses, a majority of the participants from the Guide Mode group expressed that practicing with the Guide Mode was the most helpful part of the practice sessions. Students also reported that they made greater improvement when they practiced hands separately. Some subjects also stated that the use of MIDI accompaniments helped keep their rhythm steady. Other subjects believed that the use of technology had no effect on their performance.This study investigated the effects of musical instrument digital interface (MIDI) accompaniment and computer-assisted instruction (CAI) technology on group piano students' performance accuracy and attitudes. Subjects ( N = 29) in this quasi-experimental design were non-keyboard music major college students in four intact third semester piano classes. Two of the classes were assigned to a group that practiced with the Guide Mode on Yamaha Clavinova keyboards and MIDI accompaniment, while the other two classes were assigned to a group that practiced without the Guide Mode but with MIDI accompaniment.The researcher compared the posttest scores to the pretest scores within subjects for significant differences in performance accuracy due to the treatment. Differences in pretest and posttest scores were also compared between the Guide Mode group and the MIDI-only group. Four outliers were identified as possibly skewing the data. When the outliers were removed, the group that practiced with the Guide Mode (n = 19) demonstrated significantly better improvement in total pitch errors in comparison to the control group (n = 10), p < .05. No significant difference in rhythmic errors emerged between groups. Within groups, participants made significant improvement in overall accuracy from pretests to posttests.Subjects' performances of two piano compositions were first recorded as pretests. Afterwards each class practiced the same two compositions with their respective treatment for two weeks in class. Subjects then recorded the two compositions as posttests. Three judges evaluated the pretest and posttest recordings for accuracy in pitch and rhythm. A Likert-type questionnaire investigated subjects' attitudes toward practicing with the Guide Mode and MIDI accompaniment

Failure analysis of CFRP laminates subjected to Compression After Impact: FE simulation using discrete interface elements

This paper presents a model for the numerical simulation of impact damage, permanent indentation and compression after impact (CAI) in CFRP laminates. The same model is used for the formation of damage developing during both low-velocity / low-energy impact tests and CAI tests. The different impact and CAI elementary damage types are taken into account, i.e. matrix cracking, fiber failure and interface delamination. Experimental tests and model results are compared, and this comparison is used to highlight the laminate failure scenario during residual compression tests. Finally, the impact energy effect on the residual strength is evaluated and compared to experimental results

Investigation of transition between spark ignition and controlled auto-ignition combustion in a V6 direct-injection engine with cam profile switching

Controlled auto-ignition (CAI) combustion, also known as Homogeneous Charge Compression Ignition (HCCI) can be achieved by trapping residuals with early exhaust valve closure in a direct fuel injection in-cylinder four-stroke gasoline engines (through the employment of low-lift cam profiles). Due to the operating region being limited to low and mid-load operation for CAI combustion with a low-lift cam profile, it is important to be able to operate SI combustion at high-load with a normal cam profile. A 3.0L prototype engine was modified to achieve CAI combustion, using a Cam Profile Switching mechanism which has the capability to switch between high and low-lift cam-profiles. A strategy was used where a high-profile could be used for SI combustion and a low-lift profile was used for CAI combustion. Initial analysis showed that for transitioning from SI to CAI combustion, misfire occurred on the first CAI transitional cycle. Subsequent experiments showed that the throttle opening position and switching time could be controlled avoiding misfire. Further work investigated transitioning at different loads and from CAI to SI combustion

The cascade structure of linear instability in collapsible channel flows

This paper studies the unsteady behaviour and linear stability of the flow in a collapsible channel using a fluid–beam model. The solid mechanics is analysed in a plane strain configuration, in which the principal stretch is defined with a zero initial strain. Two approaches are employed: unsteady numerical simulations solving the nonlinear fully coupled fluid–structure interaction problem; and the corresponding linearized eigenvalue approach solving the Orr–Sommerfeld equations modified by the beam. The two approaches give good agreement with each other in predicting the frequencies and growth rates of the perturbation modes, close to the neutral curves. For a given Reynolds number in the range of 200–600, a cascade of instabilities is discovered as the wall stiffness (or effective tension) is reduced. Under small perturbation to steady solutions for the same Reynolds number, the system loses stability by passing through a succession of unstable zones, with mode number increasing as the wall stiffness is decreased. It is found that this cascade structure can, in principle, be extended to many modes, depending on the parameters. A puzzling ‘tongue’ shaped stable zone in the wall stiffness–Re space turns out to be the zone sandwiched by the mode-2 and mode-3 instabilities. Self-excited oscillations dominated by modes 2–4 are found near their corresponding neutral curves. These modes can also interact and form period-doubling oscillations. Extensive comparisons of the results with existing analytical models are made, and a physical explanation for the cascade structure is proposed

An Arnoldi-frontal approach for the stability analysis of flows in a collapsible channel

In this paper, we present a new approach based on a combination of the Arnoldi and frontal methods for solving large sparse asymmetric and generalized complex eigenvalue problems. The new eigensolver seeks the most unstable eigensolution in the Krylov subspace and makes use of the efficiency of the frontal solver developed for the finite element methods. The approach is used for a stability analysis of flows in a collapsible channel and is found to significantly improve the computational efficiency compared to the traditionally used QZ solver or a standard Arnoldi method. With the new approach, we are able to validate the previous results obtained either on a much coarser mesh or estimated from unsteady simulations. New neutral stability solutions of the system have been obtained which are beyond the limits of previously used methods