Bibliographic record
Abstract
As more stringent emission limits and low consumption requirements necessary for all current vehicle propulsion systems also apply to s.i. 2-stroke engines, one of the most important design modifications that can cope with these constraints involves performing the scavenging process using pure air, which means not only fuel-free air but also oil-free air. Current two stroke s.i. engines are therefore equipped with a gasoline direct injection systems (GDI) and are the lubrication apparatus has also been modified in order to reduce both pollutant emissions and oil consumption. After a short introduction on the two stroke s.i. engine, some examples of this kind of engine that apply these new technical solutions are presented and analyzed. The second part of the paper instead presents the research activities conducted at the Energy Department Politecnico di Torino on two stroke s.i. engine over the last two decades. After presenting the first experience gained a two stroke prototype engine, the first experimental results obtained on two mass-produced crankcase scavenged 2-stroke engines, the Benelli FB-1226 and the Husqvarna WR 250, provided with gasoline direct injection, are presented. These experimental results refer to a comparison between a carburettor or gasoline indirect injection fuel feeding system with a direct fuel injection system, as far as fuel consumption and pollutant emissions are concerned. As satisfactory results were obtained, the direct injection apparatus was mounted onto a new prototype engine and the first experimental tests once more showed encouraging results, as far as fuel consumption and pollutant emissions are concerned
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.002 | 0.002 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.005 | 0.001 |
| Insufficient payload (model declined to judge) | 0.036 | 0.006 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".