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Author |
Somsen, C.; Wassermann, E.F.; Kästner, J.; Schryvers, D. |
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Title |
Precursor phenomena in a quenched and aged Ni52Ti48 shape memory alloy |
Type |
A1 Journal article |
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Year |
2003 |
Publication |
Journal de physique: 4
T2 – 10th International Conference on Martensitic Transformations, JUN 10-14, 2002, ESPOO, FINLAND |
Abbreviated Journal |
J Phys Iv |
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Volume |
112 |
Issue |
Part 2 |
Pages |
777-780 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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Abstract |
We measured the electrical resistivity R(T) and specific heat C-p(T) between room temperature (RT) and 4.2 K as well as the microstructure by transmission electron microscopy (TEM) of a Ni-52 Ti-48 SMA quenched from 1000degreesC (B2-Phase range) to RT and then annealed for 1h at T=380degreesC, 550degreesC and 650degreesC. In the “as quenched” and the “650degreesC annealed” state no martensitic transformations (MT's) occur. The diffraction patterns show faint reflections originating from coherent Ni4Ti3 precipitates in an early state of formation. Additional reflections of the type 1/2 <110>, 1/2 <111> and 1/3 <110> result from various lattice displacement waves, which are precursors of the MT's to the B19' and R-phase, respectively. Indeed, high resolution TEM micrographs of the [001] zone of the “as quenched” sample reveal transverse 1/2 <110> <110> lattice displacement waves, precursors of the B19' martensite. The coherent Ni4Ti3 precipitates, homogeneously distributed on a small length scale, binder the MT's in the “as quenched” and the “650degreesC annealed” state, and thus only the precursors appear. When annealed at T=380degreesC, however, coherent Ni4Ti3 precipitates with a length of 10nm are clearly visible in TEM. These precipitates trigger the NIT from the B2 to the R-phase on cooling, as evidenced also by anomalies in R(T) and C-p(T). Annealing at T-550degreesC leads to the well known two step MT's from the B2 to the R-phase and then into the B19'-phase. These martensitic transitions are clearly seen as additional peaks in the specific heat and anomalies in the resistance, while the “as quenched” and 650degreesC annealed samples show weak features in R(T) and C-p(T). |
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Place of Publication |
Les Ulis |
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Wos |
000186503400036 |
Publication Date |
2008-08-19 |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1155-4339; |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
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Times cited |
2 |
Open Access |
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Notes |
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Approved |
Most recent IF: NA |
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Call Number |
UA @ lucian @ c:irua:102791 |
Serial |
2694 |
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Permanent link to this record |
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Author |
Ball, J.M.; Schryvers, D. |
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Title |
The analysis of macrotwins in NiAl martensite |
Type |
A1 Journal article |
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Year |
2003 |
Publication |
Journal de physique: 4
T2 – 10th International Conference on Martensitic Transformations, JUN 10-14, 2002, ESPOO, FINLAND |
Abbreviated Journal |
J Phys Iv |
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Volume |
112 |
Issue |
Part 1 |
Pages |
159-162 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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Abstract |
We present a theoretical study of macrotwins arising in cubic to tetragonal martensitic transformations. The results help to explain some features of such macrotwins observed in Ni65Al35. |
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Place of Publication |
Les Ulis |
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Wos |
000186503200024 |
Publication Date |
2008-08-19 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1155-4339; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
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Times cited |
11 |
Open Access |
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Notes |
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Approved |
Most recent IF: NA |
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Call Number |
UA @ lucian @ c:irua:103275 |
Serial |
3569 |
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Author |
Nord, M.; Verbeeck, J. |
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Title |
Towards Reproducible and Transparent Science of (Big) Electron Microscopy Data Using Version Control |
Type |
P1 Proceeding |
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Year |
2019 |
Publication |
Microscopy and microanalysis
T2 – Microscopy & Microanalysis 2019, 4-8 August, 2019, Portland, Oregon |
Abbreviated Journal |
Microsc Microanal |
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Volume |
25 |
Issue |
S2 |
Pages |
232-233 |
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Keywords |
P1 Proceeding; Electron microscopy for materials research (EMAT) |
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Wos |
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Publication Date |
2019-08-05 |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1431-9276 |
ISBN |
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Additional Links |
UA library record |
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Impact Factor |
1.891 |
Times cited |
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Open Access |
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Notes |
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Approved |
Most recent IF: 1.891 |
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Call Number |
EMAT @ emat @c:irua:164058 |
Serial |
5377 |
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Author |
Nguyen, N.T.T.; Peeters, F.M. |
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Title |
Phase-diagram for the magnetic states of the Mn-ion subsystem in a magnetic quantum dot |
Type |
P1 Proceeding |
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Year |
2010 |
Publication |
Journal of physics : conference series
T2 – Conference on Quantum Dots 2010 (QD2010), APR 26-30, 2010, Nottingham, ENGLAND |
Abbreviated Journal |
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Volume |
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Issue |
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Pages |
012032-12034 |
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Keywords |
P1 Proceeding; Engineering sciences. Technology; Condensed Matter Theory (CMT) |
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Abstract |
The interplay between two types of spin-spin exchange interaction (namely of the electron with the Mn-ions and the Mn-ions with each other) that are governed by the positions of the Mn-ions and the magnetic field is studied in the case of a Mn-ion doped CdTe quantum dot. We investigate the formation of different magnetic phases and the existence of frustrated magnetic states due to the dominant contribution of the Mn-Mn energy. |
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Place of Publication |
Bristol |
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Wos |
000294907400032 |
Publication Date |
2010-09-21 |
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Series Editor |
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Abbreviated Series Title |
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Series Volume |
245 |
Series Issue |
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Edition |
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ISSN |
1742-6596; |
ISBN |
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Additional Links |
UA library record; WoS full record |
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Impact Factor |
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Times cited |
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Open Access |
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Notes |
; ; |
Approved |
Most recent IF: NA |
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Call Number |
UA @ lucian @ c:irua:113081 |
Serial |
2582 |
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Permanent link to this record |
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Author |
Nguyen, N.T.T.; Peeters, F.M. |
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Title |
The breakdown of Kohn's theorem in few-electron parabolic quantum dots doped with a single magnetic impurity Mn2+ |
Type |
P1 Proceeding |
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Year |
2010 |
Publication |
Journal of physics : conference series
T2 – Conference on Quantum Dots 2010 (QD2010), APR 26-30, 2010, Nottingham, ENGLAND |
Abbreviated Journal |
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Volume |
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Issue |
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Pages |
012031-12034 |
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Keywords |
P1 Proceeding; Engineering sciences. Technology; Condensed Matter Theory (CMT) |
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Abstract |
The cyclotron resonance (CR) absorption spectrum is calculated for a II-VI parabolic quantum dot (QD) containing few electrons and a single magnetic dopant (Mn(2+)). We find that Kohn's theorem no longer holds for this system and that the CR spectrum depends on the number of electrons inside the QD. The electron-Mn-ion interaction strength can be tuned for example by the magnetic field and by moving the Mn-ion to different positions inside the QD. We demonstrate that due to the presence of the Mn-ion the relative motion of the electrons couple with their center-of-mass motion through the electron-Mn-ion spin-spin exchange term resulting in an electron-electron interaction dependence of the magneto-optical absorption spectrum. At the ferromagnetic-antiferromagnetic transition we observe significant discontinuities in the CR lines. |
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Place of Publication |
Bristol |
Editor |
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Wos |
000294907400031 |
Publication Date |
2010-09-21 |
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Series Editor |
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Abbreviated Series Title |
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Series Volume |
245 |
Series Issue |
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Edition |
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ISSN |
1742-6596; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
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Times cited |
1 |
Open Access |
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Notes |
; ; |
Approved |
Most recent IF: NA |
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Call Number |
UA @ lucian @ c:irua:113080 |
Serial |
3572 |
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Permanent link to this record |
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Author |
Fitawok, M.B.; Derudder, B.; Minale, A.S.; Van Passel, S.; Adgo, E.; Nyssen, J. |
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Title |
Stakeholder perspectives on farmers' resistance towards urban land-use changes in Bahir Dar, Ethiopia |
Type |
A1 Journal article |
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Year |
2023 |
Publication |
Journal of land use science |
Abbreviated Journal |
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Volume |
18 |
Issue |
1 |
Pages |
25-38 |
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Keywords |
A1 Journal article; Engineering Management (ENM) |
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Abstract |
Owing to growing uncontrolled land-use change and urban expansion, farmers in urban fringes are struggling to sustain their livelihood. Farmers have been expressing their dissatisfaction at different times. This study analyzes the stakeholders' perspectives on the causes and outcomes of farmers' resistance to land-use change and urban expansion processes by zooming in on Bahir Dar, Ethiopia. The paper is based on focus group discussions with farmers in the neighboring villages, local agricultural extension experts, and, subsequently, key informant interviews of local government officials. Juxtaposing farmers' and local experts' positions reveals that inadequate compensations during land expropriation, lack of good governance in the urban expansion process, and inaccessibility of infrastructures are primary reasons for the farmers' struggle against urban expansion in the urban fringes. This study provides insights into the consequences of unplanned urban development challenges and may inform research and policymaking on sustainable urban development in the area and beyond. |
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Wos |
000936397600001 |
Publication Date |
2023-02-22 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1747-423x; 1747-4248 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
3.2 |
Times cited |
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Open Access |
OpenAccess |
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Notes |
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Approved |
Most recent IF: 3.2; 2023 IF: NA |
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Call Number |
UA @ admin @ c:irua:195109 |
Serial |
7368 |
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Permanent link to this record |
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Author |
Fitawok, M.B.; Derudder, B.; Minale, A.S.; Van Passel, S.; Adgo, E.; Nyssen, J. |
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Title |
Modeling the Impact of Urbanization on Land-Use Change in Bahir Dar City, Ethiopia: An Integrated Cellular Automata–Markov Chain Approach |
Type |
A1 Journal Article |
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Year |
2020 |
Publication |
Land |
Abbreviated Journal |
Land |
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Volume |
9 |
Issue |
4 |
Pages |
115 |
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Keywords |
A1 Journal Article; analytical hierarchy process; cellular automata; land-use change; Markov chain; urbanization; Engineering Management (ENM) ; |
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Abstract |
The fast-paced urbanization of recent decades entails that many regions are facing seemingly uncontrolled land-use changes (LUCs) that go hand in hand with a range of environmental and socio-economic challenges. In this paper, we use an integrated cellular automata–Markov chain (CA–MC) model to analyze and predict the urban expansion of and its impact on LUC in the city of Bahir Dar, Ethiopia. To this end, the research marshals high-resolution Landsat images of 1991, 2002, 2011, and 2018. An analytical hierarchy process (AHP) method is then used to identify the biophysical and socioeconomic factors underlying the expansion in the research area. It is shown that, during the period of study, built-up areas are rapidly expanding in the face of an overall decline of the farmland and vegetation cover. Drawing on a model calibration for 2018, the research predicts the possible geographies of LUC in the Bahir Dar area for 2025, 2034, and 2045. It is predicted that the conversions of other land-use types into built-up areas will persist in the southern, southwestern, and northeastern areas of the sprawling city, which can mainly be traced back to the uneven geographies of road accessibility, proximity to the city center, and slope variables. We reflect on how our findings can be used to facilitate sustainable urban development and land-use policies in the Bahir Dar area. |
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Wos |
000533901100026 |
Publication Date |
2020-04-09 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
2073-445X |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
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Times cited |
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Open Access |
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Notes |
The authors would like to thank the VLIR-UOS project for funding this research through Bahir Dar University—Institutional University Cooperation (BDU-IUC) program. |
Approved |
Most recent IF: NA |
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Call Number |
ENM @ enm @c:irua:169600 |
Serial |
6381 |
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Permanent link to this record |
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Author |
Chekol Zewdie, M.; Moretti, M.; Tenessa, D.B.; Ayele, Z.A.; Nyssen, J.; Tsegaye, E.A.; Minale, A.S.; Van Passel, S. |
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Title |
Agricultural technical efficiency of smallholder farmers in Ethiopia : a stochastic frontier approach |
Type |
A1 Journal article |
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Year |
2021 |
Publication |
Land |
Abbreviated Journal |
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Volume |
10 |
Issue |
3 |
Pages |
246 |
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Keywords |
A1 Journal article; Engineering Management (ENM) |
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Abstract |
In the past decade, to improve crop production and productivity, Ethiopia has embarked on an ambitious irrigation farming expansion program and has introduced new large- and small-scale irrigation initiatives. However, in Ethiopia, poverty remains a challenge, and crop productivity per unit area of land is very low. Literature on the technical efficiency (TE) of large-scale and small-scale irrigation user farmers as compared to the non-user farmers in Ethiopia is also limited. Investigating smallholder farmers' TE level and its principal determinants is very important to increase crop production and productivity and to improve smallholder farmers' livelihood and food security. Using 1026 household-level cross-section data, this study adopts a technology flexible stochastic frontier approach to examine agricultural TE of large-scale irrigation users, small-scale irrigation users and non-user farmers in Ethiopia. The results indicate that, due to poor extension services and old-style agronomic practices, the mean TE of farmers is very low (44.33%), implying that there is a wider room for increasing crop production in the study areas through increasing the TE of smallholder farmers without additional investment in novel agricultural technologies. Results also show that large-scale irrigation user farmers (21.05%) are less technically efficient than small-scale irrigation user farmers (60.29%). However, improving irrigation infrastructure shifts the frontier up and has a positive impact on smallholder farmers' output. |
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Wos |
000633846200001 |
Publication Date |
2021-03-01 |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
2073-445x |
ISBN |
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Additional Links |
UA library record; WoS full record |
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Impact Factor |
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Times cited |
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Open Access |
OpenAccess |
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Notes |
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Approved |
Most recent IF: NA |
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Call Number |
UA @ admin @ c:irua:177647 |
Serial |
6913 |
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Permanent link to this record |
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Author |
Verreck, D.; Verhulst, A.S.; Sorée, B.; Collaert, N.; Mocuta, A.; Thean, A.; Groeseneken, G. |
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Title |
Non-uniform strain in lattice-mismatched heterostructure tunnel field-effect transistors |
Type |
P1 Proceeding |
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Year |
2016 |
Publication |
Solid-State Device Research (ESSDERC), European Conference
T2 – 46th European Solid-State Device Research Conference (ESSDERC) / 42nd, European Solid-State Circuits Conference (ESSCIRC), SEP 12-15, 2016, Lausanne, SWITZERLAND |
Abbreviated Journal |
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Volume |
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Issue |
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Pages |
412-415 |
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Keywords |
P1 Proceeding; Condensed Matter Theory (CMT) |
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Abstract |
Because of its localized impact on the band structure, non-uniform strain at the heterojunction between lattice-mismatched materials has the potential to significantly enlarge the design space for tunnel-field effect transistors (TFET). However, the impact of a complex strain profile on TFET performance is difficult to predict. We have therefore developed a 2D quantum mechanical transport formalism capable of simulating the effects of a general non-uniform strain. We demonstrate the formalism for the GaAsxSb(1-x)/InyGa(1-y) As system and show that a performance improvement over a lattice-matched reference is indeed possible, allowing for relaxed requirements on the source doping. We also point out that the added design parameter of mismatch is not free, but limited by the desired effective bandgap at the tunnel junction. |
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Publisher |
Ieee |
Place of Publication |
New york |
Editor |
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Wos |
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Series Title |
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Abbreviated Series Title |
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Series Issue |
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Edition |
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ISSN |
978-1-5090-2969-3 |
ISBN |
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Additional Links |
UA library record; WoS full record |
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Impact Factor |
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Times cited |
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Open Access |
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Notes |
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Approved |
Most recent IF: NA |
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Call Number |
UA @ lucian @ c:irua:138233 |
Serial |
4358 |
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Permanent link to this record |