Ensemble Performance Research Articles

Освоение китайскими студентами русского языка в процессе вокального ансамблевого исполнительства

Освоение китайскими студентами русского языка в процессе вокального ансамблевого исполнительства

Enhancement of the Heuristic Optimization Based Extended Space Forests with Classifier Ensembles

Extended space forests are a matter of common knowledge for ensuring improvements on classification problems. They provide richer feature space and present better performance than the original feature space-based forests. Most of the contemporary studies employs original features as well as various combinations of them as input vectors for extended space forest approach. In this study, we seek to boost the performance of classifier ensembles by integrating them with heuristic optimization-based features. The contributions of this paper are fivefold. First, richer feature space is developed by using random combinations of input vectors and features picked out with ant colony optimization method which have high importance and not have been associated before. Second, we propose widely used classification algorithm which is utilized baseline classifier. Third, three ensemble strategies, namely bagging, random subspace, and random forests are proposed to ensure diversity. Fourth, a wide range of comparative experiments are conducted on widely used biomedicine datasets gathered from the University of California Irvine (UCI) machine learning repository to contribute to the advancement of proposed study. Finally, extended space forest approach with the proposed technique turns out remarkable experimental results compared to the original version and various extended versions of recent state-of-art studies

Study on the Construction of Initial Condition Perturbations for the Regional Ensemble Prediction System of North China

The regional ensemble prediction system (REPS) of North China is currently under development at the Institute of Urban Meteorology, China Meteorological Administration, with initial condition perturbations provided by global ensemble dynamical downscaling. To improve the performance of the REPS, a comparison of two initial condition perturbation methods is conducted in this paper: (i) Breeding, which was specifically designed for the REPS, and (ii) Dynamical downscaling. Consecutive tests were implemented to evaluate the performances of both methods in the operational REPS environment. The perturbation characteristics were analyzed, and ensemble forecast verifications were conducted. Furthermore, a heavy precipitation case was investigated. The main conclusions are as follows: the Breeding perturbations were more powerful at small scales, while the downscaling perturbations were more powerful at large scales; the difference between the two perturbation types gradually decreased with the forecast lead time. The downscaling perturbation growth was more remarkable than that of the Breeding perturbations at short forecast lead times, while the perturbation magnitudes of both schemes were similar for long-range forecasts. However, the Breeding perturbations contained more abundant small-scale components than downscaling for the short-range forecasts. The ensemble forecast verification indicated a slightly better downscaling ensemble performance than that of the Breeding ensemble. A precipitation case study indicated that the Breeding ensemble performance was better than that of downscaling, particularly in terms of location and strength of the precipitation forecast.

FNIRS Responses in Professional Violinists While Playing Duets: Evidence for Distinct Leader and Follower Roles at the Brain Level.

Music played in ensembles is a naturalistic model to study joint action and leader-follower relationships. Recently, the investigation of the brain underpinnings of joint musical actions has gained attention; however, the cerebral correlates underlying the roles of leader and follower in music performance remain elusive. The present study addressed this question by simultaneously measuring the hemodynamic correlates of functional neural activity elicited during naturalistic violin duet performance using fNIRS. Findings revealed distinct patterns of functional brain activation when musicians played the Violin 2 (follower) than the Violin 1 part (leader) in duets, both compared to solo performance. More specifically, results indicated that musicians playing the Violin 2 part had greater oxy-Hb activation in temporo-parietal (p = 0.02) and somatomotor (p = 0.04) regions during the duo condition in relation to the solo. On the other hand, there were no significant differences in the activation of these areas between duo/solo conditions during the execution of the Violin 1 part (p’s > 0.05). These findings suggest that ensemble cohesion during a musical performance may impose particular demands when musicians play the follower position, especially in brain areas associated with the processing of dynamic social information and motor simulation. This study is the first to use fNIRS hyperscanning technology to simultaneously measure the brain activity of two musicians during naturalistic music ensemble performance, opening new avenues for the investigation of brain correlates underlying joint musical actions with multiple subjects in a naturalistic environment.

A Systematic Literature Review and Meta-Analysis on Cross Project Defect Prediction

Background: Cross project defect prediction (CPDP) recently gained considerable attention, yet there are no systematic efforts to analyse existing empirical evidence. Objective: To synthesise literature to understand the state-of-the-art in CPDP with respect to metrics, models, data approaches, datasets and associated performances. Further, we aim to assess the performance of CPDP versus within project DP models. Method: We conducted a systematic literature review. Results from primary studies are synthesised (thematic, meta-analysis) to answer research questions. Results: We identified 30 primary studies passing quality assessment. Performance measures, except precision, vary with the choice of metrics. Recall, precision, f-measure, and AUC are the most common measures. Models based on Nearest-Neighbour and Decision Tree tend to perform well in CPDP, whereas the popular naive Bayes yields average performance. Performance of ensembles varies greatly across f-measure and AUC. Data approaches address CPDP challenges using row/column processing, which improve CPDP in terms of recall at the cost of precision. This is observed in multiple occasions including the meta-analysis of CPDP versus WPDP. NASA and Jureczko datasets seem to favour CPDP over WPDP more frequently. Conclusion: CPDP is still a challenge and requires more research before trustworthy applications can take place. We provide guidelines for further research.

Volta basin precipitation and temperature climatology: evaluation of CORDEX-Africa regional climate model simulations

Here, an evaluation of nine simulations of the regional climate models (RCM) performed within the frame of CORDEX-Africa Project to reproduce the Volta Basin climatology (1971–2005) is presented. Performance metrics of climatological means were computed from annual, seasonal, and monthly total values which detect differences in the spatial and temporal structures of the model outputs with observational datasets for precipitation and temperature evaluated over three sub-domains (the Guinea Coast, the Soudano-Sahel, and the Sahel) within the basin. The results reveal pronounced influence of the GCM-derived boundary conditions at homogeneous zones, for example, CNRM-induced model overestimations over the Sahel. A good replica of the spatial distribution of climatic parameters particularly for temperature with biases within 0.1 °C and obvious wet bias for precipitation up to 40% is detected predominantly over the Sahel with widespread differences in spatial extent and intensities. A better performance is obtained for summer and fall but worse in spring for precipitation. The analysis showed that the basic characteristics of the West African climate are reasonably reproduced by the models, including its variability in sign, amplitude, and spatial extent, but also, there are recognized deficiencies of the model simulations for some selected metrics, regions, and seasons. The study emphasizes on individual model skills than in ensemble performance, and CanESM2-RCA4 and NorESM1-RCA4 RCMs were realized to replicate best the observed dataset so these models are recommended for impact studies over the basin for most seasons. Results achieved will be valuable in the choice of GCMs/RCMs for impact study over the basin, and we conclude that this may also depend on the focus of interest, whether it is a study on variability and process representation or region of study or timescales.

A review of evidence about use and performance of species distribution modelling ensembles like BIOMOD

AbstractAimThe idea of combining predictions from different models into an ensemble has gained considerable popularity in species distribution modelling, partly due to free and comprehensive software such as the R package BIOMOD. However, despite proliferation of ensemble models, we lack oversight of how and where they are used for modelling distributions, and how well they perform. Here, we present such an overview.LocationGlobal.MethodsSince BIOMOD is freely available and widely used by ensemble species distribution modellers, we focused on articles that apply BIOMOD, filtering the initial 852 papers identified in our structured literature search to a relevant final subset of 224 eligible peer‐reviewed journal articles.ResultsBIOMOD‐based ensembles are used across many taxa and locations, with terrestrial plants being the most represented group of species (n = 72) and Europe being the most represented continent (n = 106). These studies often focus on forecasting distributions in the future (n = 109), and commonly use presence‐only species data (n = 139) and climatic environmental predictors (n = 219). An average of six models are used in ensembles, and approximately half of ensembles weight contributions of models by their cross‐validation performance. However, discussion about choices made in the modelling process and unambiguous information on the performance of ensemble models versus individual models are limited. The use of independent data to validate model performance is particularly uncommon.Main conclusionsWe document the breadth of ensemble applications, but could not draw strong quantitative conclusions about the predictive performance of ensemble models, due to lack of unambiguous information reported. Understanding how and where ensembles are best used when modelling species distributions is important for enabling best choices for different applications. To enable this objective to be achieved, we provide recommendations for thorough reporting practices in a BIOMOD‐based ensemble workflow.

Body sway reflects joint emotional expression in music ensemble performance

Joint action is essential in daily life, as humans often must coordinate with others to accomplish shared goals. Previous studies have mainly focused on sensorimotor aspects of joint action, with measurements reflecting event-to-event precision of interpersonal sensorimotor coordination (e.g., tapping). However, while emotional factors are often closely tied to joint actions, they are rarely studied, as event-to-event measurements are insufficient to capture higher-order aspects of joint action such as emotional expression. To quantify joint emotional expression, we used motion capture to simultaneously measure the body sway of each musician in a trio (piano, violin, cello) during performances. Excerpts were performed with or without emotional expression. Granger causality was used to analyze body sway movement time series amongst musicians, which reflects information flow. Results showed that the total Granger-coupling of body sway in the ensemble was higher when performing pieces with emotional expression than without. Granger-coupling further correlated with the emotional intensity as rated by both the ensemble members themselves and by musician judges, based on the audio recordings alone. Together, our findings suggest that Granger-coupling of co-actors’ body sways reflects joint emotional expression in a music ensemble, and thus provide a novel approach to studying joint emotional expression.

Eye gaze as a means of giving and seeking information during musical interaction.

During skilled music ensemble performance, a multi-layered network of interaction processes allows musicians to negotiate common interpretations of ambiguously-notated music in real-time. This study investigated the conditions that encourage visual interaction during duo performance. Duos recorded performances of a new piece before and after a period of rehearsal. Mobile eye tracking and motion capture were used in combination to map uni- and bidirectional eye gaze patterns. Musicians watched each other more during temporally-unstable passages than during regularly-timed passages. They also watched each other more after rehearsal than before. Duo musicians may seek visual interaction with each other primarily, but not exclusively, when coordination is threatened by temporal instability. Visual interaction increases as musicians become familiar with the piece, suggesting that they visually monitor each other once a shared interpretation of the piece is established. Visual monitoring of co-performers' movements and attention may facilitate feelings of engagement and high-level creative collaboration.

Ансамблевое музицирование в зеркале западноевропейской живописи XVII – XVIII веков

During the Baroque era ensemble music-making was a favorite pastime. For the nobility and the middle class “communication by means of music” was an inherent part of life: the musical language was the means of expressing respect, presenting “musical offerings” and confessions of love. In musical competitions virtuosi demonstrated their exceptional performing skills, and high-society ladies accompanied readings of poetical works with playing the harp or the lute. The desire to make music in the form of solo or ensemble performance was shared by players on various instruments endowed with different levels of preparedness. This “social demand” resulted in the appearance of the two-staff form of notation, endowed with traits of a quasi-score, which it was customary to call the keyboard urtext. However, this music can be termed as being for the keyboard only upon the condition of their performance on the organ or the harpsichord. The structure of the “two-staff scores” from the 17th and 18th centuries possesses immense possibilities, since it presents a universal form of notation for ensemble and orchestral compositions in convolved form. As the result of the traits of the quasi-score, the baroque urtext became a unique phenomenon, a peculiar “mirror of the epoch”, which registered numerous 17th and 18th century musical instrumental clichés, scenes of music-making in duos, trios, and even images of groups of the baroque orchestra — the solo and the continuo. A sort of mirror reflecting pictures of music-making and ensemble groups was provided by the art canvases of 17th and 18th century painters.

Тема детства во французской музыке XIX века: к постановке проблемы

The paper describes piano and vocal music of the 19th-century French composers – Ch. Alkan, Ch. Gounod, J. Bizet, and G. Fauré. The research does not focus that much on the analysis of musical language of selected works, rather, it explores their historical and cultural context as well as some of the reasons for their appearance. The theme of childhood in the 19th-century French musical culture has a special role. It naturally follows from the general attention to childhood demonstrated by philosophers, educators, and writers of the 18th-19th centuries, and has several ideas behind. Firstly, an idea of educating a music lover. The Biedermeier style (in its French version) and the fashion for domestic music-making created a demand for easy and convenient pieces for solo and ensemble performance. The priority was given to piano four-hands and songs for voice and piano. Secondly, the opening of Paris Conservatory, numerous other music education institutions as well as private music classes required the development of educational material for beginner musicians of different ages. Thirdly, this is a special vision of composers that combined naivety, humor and nostalgia. This mix does not only shape the imagery of selected works, but also the composer’s preference for certain genres, forms and systems of expressive means. To conclude it should be noted that the theme of childhood in the 19th-century French music is a remarkable phenomenon worthy of further consideration.

Rational design of functional materials guided by single particle chemiluminescence imaging.

Chemiluminescence (CL) functionalized materials have found tremendous value in developing CL assays for clinical assays and point-of-care tests. To date, the design and optimization of these materials have mainly relied on conventional trial-and-error procedures in which the ensemble performance is evaluated using conditional experiments. Here we have built an optical microscope to acquire the CL emission from single magnetic-polymer hybrid microbeads functionalized with luminol analogues, and to access the CL kinetics of each individual particle. It was incidentally found that a minor subpopulation of microbeads exhibited intense and delayed CL emission while the majority showed transient and weak emission. Structural characterization of the very same individual particles uncovered that the amorphous multi-core microstructures were responsible for the enhanced encapsulation efficiency and optimized CL reaction kinetics. Guided by this knowledge stemming from single particle CL imaging, the synthesis procedure was rationally optimized to enrich the portion of microbeads with better CL performance, which was validated by both single particle imaging and the significantly improved analytical performance at the ensemble level. The present work not only demonstrates the CL imaging and CL kinetics curve of single microbeads for the first time, but also sets a clear example showing the capability of single particle studies to investigate the structure-activity relationship in a bottom-up manner and to help the rational design of ensemble materials with improved performance.

A Diversity-Accuracy Measure for Homogenous Ensemble Selection

Several selection methods in the literature are essentially based on an evaluation function that determines whether a model M contributes positively to boost the performances of the whole ensemble. In this paper, we propose a method called DIversity and ACcuracy for Ensemble Selection (DIACES) using an evaluation function based on both diversity and accuracy. The method is applied on homogenous ensembles composed of C4.5 decision trees and based on a hill climbing strategy. This allows selecting ensembles with the best compromise between maximum diversity and minimum error rate. Comparative studies show that in most cases the proposed method generates reduced size ensembles with better performances than usual ensemble simplification methods

Fractionally delayed Legendre wavelet transform based detection and optimal features based classification of voltage sag causes

Detection of underlying causes of voltage sag is more crucial than detection of voltage sag from the mitigation point of view. Therefore, this paper proposes the detection and classification of the eight causes of voltage sag. This approach augments the conventional technique of wavelet transform by designing the fractionally delayed Legendre wavelet as the signal processing tool. The unique event characteristics are sought from approximation, and detailed signal coefficients which are obtained by using 4-level multiresolution analysis. To achieve a higher classification rate, the best optimal features are rummaged around the extracted features by employing the ant lion optimization algorithm. This algorithm retains only the suitable features as per the fitness criterion based on the classification accuracy and number of features. The representative feature set is classified using the classifier ensemble employing plural majority voting. The classifier ensemble has three members which are support vector machine, probabilistic neural network, and multilayer neural network. Better performance of the classifier ensemble is observed as compared to individual members in classification of voltage sag causes. The efficacy of the proposed methodology has been validated in the presence of noise also. This approach has successfully classified the causes of voltage sag using optimal features with good accuracy in the case of both noiseless signals and noisy signals.

Formation of professional qualities of the future head of vocal-instrumental collective in the process of ensemble performance

Formation of professional qualities of the future head of vocal-instrumental collective in the process of ensemble performance

The Aesthetics and Ethics of Contemporary Female Songstress in Javanese Ensemble

The research is financed by Lembaga DIPA LP2P3M Indonesia Institute of the Arts Surakarta 2018 Abstract Javanese people had various arts and cultures, including karawitan (Javanese ensemble). Javanese ensemble was one of the traditional arts that was still popular and was maintained until now. Surakarta-style Javanese ensemble had elaborate garap instruments, also had garap vocal that was no less complicated than garap instruments. The so-called vocal was: sindhènan. In this study, sindhèn (songstress) was deliberately chosen as the object of study, because sindhèn still existed and had musical and social strength. This was evident in every performance, both in independent musical performances and as supporter of other performing arts, sindhèn always came with its aesthetics. In the last decade, many young sindhèns had little concern for the sindhènan musical principles. In the end, it caused lack of good qualities of the sindhènan that they did. They justified the fact with, " sing penting payu (what matters was that my service could be sold)". Based on this fact, this study seeked to uncover problems related to sindhèn in klenengan performances, including: 1) Why was sindhèn become an important element in Javanese ensemble?, 2) How did the influence of sindhèn on klenèngan performances? Both problems were revealed using garap theory and aesthetic theory. The accumulation of various analyzes carried out in this study, essentially led to the goal of being able to produce a research finding that was centered on the essence of the problem. This was a qualitative research. Information was collected through literature studies, interviews, and direct observations of sindhèn’s performances in Surakarta-style Javanese ensemble shows. This study found that sindhèn needed aesthetics and ethics. Aesthetics included, céngkok, luk, wiled, and gregel. While in this term, ethics was meant as the manners of a sindhèn in Javanese ensemble performances. The way sindhèn acted, greatly influenced the klenenngan performances, because it could give its own satisfaction to those who liked performing arts. Keywords: Javanese ensemble, sindhèn , aesthetic, ethics DOI : 10.7176/RHSS/9-2-10

Evaluation and projected changes in daily rainfall characteristics over Central Africa based on a multi-model ensemble mean of CMIP5 simulations

This study uses daily rainfall data from 20 global climate models (GCMs) simulations, participating in the phase 5 of the Coupled Model Intercomparison Project (CMIP5) and eight daily rainfall indices defined by the Expert Team on Climate Change Detection and Indices (ETCCDI), to investigate the changes in extreme weather conditions over Central Africa under the representative concentration pathway 8.5. The performance of the multi-model ensemble (MME) mean which in fact refers to the best performing models selected through the Taylor diagram analysis was evaluated by comparing with two gridded daily observation datasets during the historical period (1998–2005). Results show that although some uncertainties may exist between the gridded observation datasets, MME consistently outperform individual models and reasonably reproduced the observed pattern of daily rainfall indices over the region, except in the case of consecutive wet day (CWD) where the high variability of individual members has resulted in the degradation of the overall skill of the MME. The assessment of the climate change signal in the eight daily rainfall indices was done for the mid and late twenty-first century (2026–2056 and 2066–2095 respectively), relative to the baseline historical time period (1976–2005). We found a significant increase in the total wet day rainfall amount (PRCPTOT) over southern (northern) Central Africa from December to February (from September to November). This is mainly due to the increase of high intense rainfall events rather than their frequency. The results also reveal that the increase in PRCPTOT was coupled with increase in the maximum consecutive 5-day rainfall amount (RX5DAY), the 95th percentile (R95), and the total wet day rainfall amount above the 95th percentile (R95PTOT), with more robust patterns of change at the late twenty-first century. The increase in extreme rainfall events (RX5DAY, R95, and R95PTOT) is likely to increase flood risks over Cameroon, Central African Republic, Gabon, Congo, Angola, Zambia, and Democratic Republic of Congo. On the other hand, changes in CWD and PRCPTOT are projected to significantly decrease over Angola, Zambia, and Democratic Republic of Congo from September to November. This is due to a substantial increase of zonal moisture divergence fluxes in upper atmospheric layers. The analysis has also shown that areas where CWD and PRCPTOT decreases coincides with those where consecutive dry days (CDD) increase. The decrease in CWD and PRCPTOT coupled with the increase in CDD could worsen drought risk and significantly disrupt priority socio-economic sectors for development such as rain-fed agriculture, hydroelectric power generation, and water resource availability. The results thus underline the importance for decision-makers to seriously consider adaptation and mitigation measures, in order to limit the risks of natural disasters such as severe droughts and floods that Central African countries may suffer in the future.

Organising Sound with Audio Clothes: An interview with Benoit Maubrey

Benoit Maubrey’s work with audio art started in Berlin in 1982 with public sound sculptures, and he eventually turned to performative practices with portable audio embedded in clothes and costumes. His artistic practice currently spans site-specific and non-site-specific sound installations, locational and non-locational performances, as well as performed, interactive and non-interactive sound installations, and a comprehensive description of his artistic trajectory is planned for release in 2019: Benoit Maubrey – Sound Sculptures. His most well-known ensemble is The Audio Ballerinas, wearing tutus with a combination of solar cells, light sensors, samplers, radios, amplifiers and loudspeakers. The ensemble has been performing since its debut in Lille in 1990. Maubrey has developed a huge portfolio of audio ensemble performances on several continents, and an interesting thread of autonomy and critical reflection is running through his oeuvre. The costumes and their technical affordances have changed with new technological developments, and in this interview Maubrey explains these developments, and how he has maintained and extended his artistic focus.

Improved performance of a PRECIS ensemble in simulating near-surface air temperature over China

The near-surface air temperature over China is simulated from 1950 to 2099 using the PRECIS model from the Met Office Hadley Centre at a 25-km resolution. In order to reflect the different parametric and structural uncertainties in future temperature projections, the PRECIS model is driven by five lateral boundary conditions, which include a four-member HadCM3-based perturbed-physics ensemble (i.e., HadCM3Q0, Q1, Q7 and Q13) and an ECHAM5 model. For the present climate, PRECIS reasonably reproduces the spatial patterns of near-surface air temperatures over most regions in China, except for some underestimation in the west. The annual cycles of mean temperature are well captured but its magnitude is slightly underestimated throughout the year. Future temperature projections are further analyzed for three successive 30-year periods throughout the twenty-first century. Despite more uncertainties with time, the ensemble results demonstrate that the temperature over China is likely to continue to increase throughout the twenty-first century, with different spatial-time variation. There is an apparent increasing pattern along with the latitude for seasonal temperature. Through comparison with the driving GCMs, PRECIS ensemble shows smaller biases in most regions of China, except for in the west plateau. The cause is that RCMs could inherit some errors from the driving GCMs in addition to their own errors. These errors could be magnified unintentionally in downscaling over high elevations and have been propagated into future climate projections. However, there is no apparent relationship between projected changes and model biases (i.e., larger bias does not necessarily lead to bigger changes in temperature). These results could be directly used to analyze the impacts caused by climate warming on agriculture, energy and other related sectors in China.

A first-of-its-kind multi-model convection permitting ensemble for investigating convective phenomena over Europe and the Mediterranean

A recently launched project under the auspices of the World Climate Research Program’s (WCRP) Coordinated Regional Downscaling Experiments Flagship Pilot Studies program (CORDEX-FPS) is presented. This initiative aims to build first-of-its-kind ensemble climate experiments of convection permitting models to investigate present and future convective processes and related extremes over Europe and the Mediterranean. In this manuscript the rationale, scientific aims and approaches are presented along with some preliminary results from the testing phase of the project. Three test cases were selected in order to obtain a first look at the ensemble performance. The test cases covered a summertime extreme precipitation event over Austria, a fall Foehn event over the Swiss Alps and an intensively documented fall event along the Mediterranean coast. The test cases were run in both “weather-like” (WL, initialized just before the event in question) and “climate” (CM, initialized 1 month before the event) modes. Ensembles of 18–21 members, representing six different modeling systems with different physics and modelling chain options, was generated for the test cases (27 modeling teams have committed to perform the longer climate simulations). Results indicate that, when run in WL mode, the ensemble captures all three events quite well with ensemble correlation skill scores of 0.67, 0.82 and 0.91. They suggest that the more the event is driven by large-scale conditions, the closer the agreement between the ensemble members. Even in climate mode the large-scale driven events over the Swiss Alps and the Mediterranean coasts are still captured (ensemble correlation skill scores of 0.90 and 0.62, respectively), but the inter-model spread increases as expected. In the case over Mediterranean the effects of local-scale interactions between flow and orography and land–ocean contrasts are readily apparent. However, there is a much larger, though not surprising, increase in the spread for the Austrian event, which was weakly forced by the large-scale flow. Though the ensemble correlation skill score is still quite high (0.80). The preliminary results illustrate both the promise and the challenges that convection permitting modeling faces and make a strong argument for an ensemble-based approach to investigating high impact convective processes.