AlSi12 Alaşımından Üretilen Kompresör Silindir Kapağında Abrasif Aşınma Davranışının İncelenmesi

Bu çalışmada havalı fren kompresör silindir kafası üretiminde kullanılan aynı kimyasal bileşime sahip fakat farklı morfolojide iki farklı AlSi12 alaşımının aşınma dirençleri incelenmiştir. Yüksek basınçlı döküm yöntemiyle üretilmiş ürünler abrasif aşınmaya maruz bırakılmıştır. Aşınma deneyleri, kuvvet kontrollü test cihazında 600 mesh SiC zımpara, 10, 20 ve 30N yükleri altında 300 rpm dönme hızında yapılmıştır. Abrasif aşınma test sonuçlarına göre, küresel dendritlere sahip alaşımın aşınma davranışının daha iyi olduğu sonucu ortaya çıkmıştır

Fracture resistance of root-filled teeth after cavity preparation with conventional burs, Er: YAG and Er,Cr: YSGG lasers

Purpose The aim of the present study is to compare the fracture resistance of teeth after access cavity preparation with conventional rotary burs, Erbium-doped yttrium aluminum garnet laser (Er:YAG) and Erbium, cromium: yttrium scandium gallium garnet laser (Er,Cr:YSGG) lasers. Materials and methods Fifty five intact mandibular molars were divided into 3 negative groups (groups 1, 2, 3; n=5 for each), 3 study groups (groups 4, 5, 6; n=10 for each) and 1 positive control group (intact teeth; n=10). Access cavities of groups 1, 2 and 3 were prepared with conventional burs, Er:YAG laser and Er,Cr:YSGG laser respectively. After root canal obturation, their coronal portions were left non-restored. Access cavities of groups 4, 5 and 6 were prepared by using the same equipment but their coronal portions were restored with composite resinafter root canal obturation. Following thermocycling, fracture strength was evaluated with a Universal Testing Machine. Mean force at which each sample is fractured was recorded in Newton unit and statistically analyzed. Results Fracture resistance of group 7 (intact teeth) was significantly higher than all other groups (p<0.001). Differences among the fracture resistance values of groups 4, 5 and 6 were not significantly different but they were significantly higher than those of groups 1, 2 and 3 (p<0.001). No significant difference was found between Groups 1, 2 and 3. Conclusion Preparing access cavities with either laser or bur has no effect on the fracture resistance of teeth with root canal treatment

AlSi12 Alaşımından Üretilen Kompresör Silindir Kapağında Abrasif Aşınma Davranışının İncelenmesi

Bu çalışmada havalı fren kompresör silindir kafası üretiminde kullanılan aynı kimyasal bileşime sahip fakat farklı morfolojide iki farklı AlSi12 alaşımının aşınma dirençleri incelenmiştir. Yüksek basınçlı döküm yöntemiyle üretilmiş ürünler abrasif aşınmaya maruz bırakılmıştır. Aşınma deneyleri, kuvvet kontrollü test cihazında 600 mesh SiC zımpara, 10, 20 ve 30N yükleri altında 300 rpm dönme hızında yapılmıştır. Abrasif aşınma test sonuçlarına göre, küresel dendritlere sahip alaşımın aşınma davranışının daha iyi olduğu sonucu ortaya çıkmıştır

AlSi12 Alaşımından Üretilen Kompresör Silindir Kapağında Abrasif Aşınma Davranışının İncelenmesi

Bu çalışmada havalı fren kompresör silindir kafası üretiminde kullanılan aynı kimyasal bileşime sahip fakat farklı morfolojide iki farklı AlSi12 alaşımının aşınma dirençleri incelenmiştir. Yüksek basınçlı döküm yöntemiyle üretilmiş ürünler abrasif aşınmaya maruz bırakılmıştır. Aşınma deneyleri, kuvvet kontrollü test cihazında 600 mesh SiC zımpara, 10, 20 ve 30N yükleri altında 300 rpm dönme hızında yapılmıştır. Abrasif aşınma test sonuçlarına göre, küresel dendritlere sahip alaşımın aşınma davranışının daha iyi olduğu sonucu ortaya çıkmıştır

Estimation of emissions from crop residue burning in Türkiye using remotely sensed data and the Google Earth Engine platform

This research aims to find crop-based residue burning (CRB) amounts for the Southeastern Anatolia Region of Türkiye, where versatile and diverse of agricultural fields are available. We used the time series of Sentinel-2 images to identify spatial distribution of different crop types and to determine the burned agricultural fields in 2019 using Google Earth Engine platform. We implemented Intergovernmental Panel on Climate Change standards to calculate the emissions from Greenhouse gases and Particulate Matter. We also analyzed Sentinel-5P images to generate Nitrogen Dioxide maps and compared them with crop-based emission calculations. Our analysis illustrated that 14,444.307 Gg of Greenhouse Gases and 117.809 Gg of Particulate Matters were released in 2019 due to CRB practices. Our results can potentially improve the national statistics by providing spatio-temporal field-based CRB emissions and supporting country-level agricultural decision-making processes. Researchers could implement our proposed data and methodology in other regions suffering from the CRB problem

One Observation behind Two-Envelope Puzzles

and popular puzzles a participant is required to compare two numbers of which she is shown only one. Although the puzzles have been discussed and explained extensively, no connection between them has been established in the literature. We show here that there is one simple principle behind these puzzles. In particular, this principle sheds new light on the paradoxical nature of the first puzzle. According to this principle the ranking of several random variables must depend on at least one of them, except for the trivial case where the ranking is constant. Thus, in the nontrivial case there must be at least one variable the observation of which conveys information about the ranking. A variant of the first puzzle goes back to the mathematician Littlewood [7], who attributed it to the physicist Schrödinger. See [6], [3], [2]and[1] for more detail on the historical background and for further elaboration on this puzzle. Here is the common version of the puzzle, as first appeared in [5]: To switch or not to switch? There are two envelopes with money in them. The sum of money in one of the envelopes is twice as large as the othe

Evaluating the potential of multi-temporal Sentinel-1 and Sentinel-2 data for regional mapping of olive trees

Olives are a crucial economic crop in Mediterranean countries. Detailed spatial information on the distribution and condition of crops at regional and national scales is essential to ensure the continuity of crop quality and yield efficiency. However, most earlier studies on olive tree mapping focused mainly on small parcels using single-sensor, very high resolution (VHR) data, which is time-consuming, expensive and cannot feasibly be scaled up to a larger area. Therefore, we evaluated the performance of Sentinel-1 and Sentinel-2 data fusion for the regional mapping of olive trees for the first time, using the Izmir Province of Türkiye, an ancient olive-growing region, as a case study. Three different monthly composite images reflecting the different phenological stages of olive trees were selected to separate olive trees from other land cover types. Seven land-cover classes, including olives, were mapped separately using a random forest classifier for each year between 2017 and 2021. The results were assessed using the k-fold cross-validation method, and the final olive tree map of Izmir was produced by combining the olive tree distribution over two consecutive years. District-level areas covered by olive trees were calculated and validated using official statistics from the Turkish Statistical Institute (TUIK). The K-fold cross-validation accuracy varied from 94% to 95% between 2017 and 2021, and the final olive map achieved 98% overall accuracy with 93% producer accuracy for the olive class. The district-level olive area was strongly related to the TUIK statistics (R 2 = 0.60, NRMSE = 0.64). This study used Sentinel data and Google Earth Engine (GEE) to produce a regional-scale olive distribution map that can be scaled up to the entire country and replicated elsewhere. This map can, therefore, be used as a foundation for other scientific studies on olive trees, particularly for the development of effective management practices.</p