Intentional Islanding of Active Distribution Networks by GenSets: An Analysis of Technical Constraints and Opportunities

The willingness to improve the security and reliability of power supply to end-users, often pushed by prescriptions of national regulatory authorities, is bringing considerable challenges for distribution system operators. Islanding a portion of the public distribution network after a fault is considered a measure to mitigate the effects of service interruptions. This procedure is usually carried out by counterfeeding the grid through a generator set (GenSet). Even if this approach is widely adopted around the world, reenergizing the grid and keeping the electric island stable is not a trivial task. In this framework, the scope of this paper is to provide a set of technical guidelines for the usage of GenSets to supply public grids in emergency conditions. The goal is to highlight the static and dynamic limits of the GenSet operations and simplify their exploitation for the grid operators. The numerical analyses, which have been carried out through the RMS simulation tool of the DigSilent PowerFactory software, also aim to evaluate the technical constraints in the case of active networks, which involve distributed generation implementing regulations according to ENTSO-E and Italian technical standards

ESR Processing of a New HighPressureDieCasting Steel

Schmiedewerke Groditz (SWG) is among the global players of special re-melted steel alloys production. Within the RFCS project n⁰ 751360 HPDCSTEEL (High Pressure Die Casting Steel) a new ESR steel grade has been developed. At SWG the steel grade was produced using an open ESR unit. During re-melting the master alloy has been continuously added into the liquid slag bath and a modified ESR ingot of 20t has been manufactured. The ESR process was modified to increase the quality and performance of the steel, maintaining a constant distribution of synthetic carbides into the obtained ingot. A master alloy was placed on the bottom of the ESR machine before starting with the pre-charge. Furthermore, during re-melting the master alloy has been fed continuously using an installed balance system. No problems in the steel processing were detected, with a standard ESR melting and permanent feeding of the new alloy. The chemical composition of the alloy and of the liquid ESR slag was measured several times during the re-melting process, to determine if the master alloy was correctly dissolved in the melt

Learning Opinion Dynamics From Social Traces

Opinion dynamics - the research field dealing with how people's opinions form and evolve in a social context - traditionally uses agent-based models to validate the implications of sociological theories. These models encode the causal mechanism that drives the opinion formation process, and have the advantage of being easy to interpret. However, as they do not exploit the availability of data, their predictive power is limited. Moreover, parameter calibration and model selection are manual and difficult tasks. In this work we propose an inference mechanism for fitting a generative, agent-like model of opinion dynamics to real-world social traces. Given a set of observables (e.g., actions and interactions between agents), our model can recover the most-likely latent opinion trajectories that are compatible with the assumptions about the process dynamics. This type of model retains the benefits of agent-based ones (i.e., causal interpretation), while adding the ability to perform model selection and hypothesis testing on real data. We showcase our proposal by translating a classical agent-based model of opinion dynamics into its generative counterpart. We then design an inference algorithm based on online expectation maximization to learn the latent parameters of the model. Such algorithm can recover the latent opinion trajectories from traces generated by the classical agent-based model. In addition, it can identify the most likely set of macro parameters used to generate a data trace, thus allowing testing of sociological hypotheses. Finally, we apply our model to real-world data from Reddit to explore the long-standing question about the impact of backfire effect. Our results suggest a low prominence of the effect in Reddit's political conversation.Comment: Published at KDD202

Desain Sistem Pipa Distribusi Gas untuk Sektor Perumahan dan Komersial di Wilayah Kebayoran Baru – Jakarta Selatan

Pemanfaatan gas alam di Indonesia untuk sektor Perumahan dan komersial masih belum optimum, termasuk di wilayah ibukota. Berbagai kebijakan telah dirumuskan pemerintah untuk mendukung pemanfaatan gas alam termasuk meningkatkan infrastruktur penyaluran gas alam. Tujuan utama dari studi ini adalah untuk melakukan perancangan sistem pipa distribusi gas untuk sektor Perumahan dan komersial di wilayah Kebayoran Baru (Jakarta Selatan) serta melakukan analisa kelayakan ekonomi dari proyek tersebut. Kebayoran Baru adalah wilayah yang potensial untuk dilakukan pengembangan gas kota. Berdasarkan perhitungan yang telah dilakukan di studi ini, kebutuhan gas untuk sektor Perumahan dan komersial di Kebayoran Baru adalah sekitar 0,9 MMSCFD. Studi ini mencakup pula pemilihan rute untuk sistem pipa distribusi gas di wilayah tersebut. Berdasarkan hasil simulasi dengan perangkat lunak Fluid Flow dan dikonversi dengan spesifikasi pipa komersial yang ada di pasaran, diameter pipa yang akan digunakan adalah 180 mm, 90 mm, dan 63 mm. Total panjang pipa distribusi tersebut adalah 20,3 m. Dari hasil studi ini, rancangan tersebut akan layak dari segi ekonomi apabila harga jual gas sebesar Rp3.141/m3dan harga ini lebih rendah dibandingkan harga LPG untuk wilayah Jakarta

Relationship between lactation curve function and phenotypic variance in random regression Test Day models

In Random Regression models (RRM), the most updated version of Test Day (TD) models, the lactation curve is split into a fixed average curve and a random animal specific part (deviation from the average curve) (Schaeffer, 2004). The variance component of the RR coefficients determines the (co) variance function of each pair of days in milk (DIM) (Pool and Meuwissen, 2000). Very different patterns of variance functions have been reported in literature, and several authors pointed out a possible rule of the type of function chosen as RR sub-model and data structure (Kettunen et al., 2000; Meyer, 1998). Aim of this work is to investigate some possible reasons for such results, in particular the effects of the mathematical function and of the possible occurrence of different shapes of lactation curve (regular and atypical)