4,563 research outputs found

    Teachers’ Conflict-Inducing Attitudes and Their Repercussions on Students’ Psychological Health and Learning Outcomes

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    This paper studied the causes and effects of negative teacher–student relationships on students’ psychological health and educational outcomes, primarily due to negative teacher–teacher interactions. Survey data were collected from 130 faculty members and 746 students of 10 higher educational institutions located in different cities of the Punjab province of Pakistan. Path analysis was used to estimate results. The findings revealed that incivility among faculty members and higher discontent with university resources generates a conflict-inducing attitude in faculty members, which subsequently creates negative behavior in teachers towards students. It was further observed that hostile attitudes of faculty members towards students adversely affects the psychological health and educational outcomes of students at universities. These findings suggest that students’ learning processes can be improved by controlling negative teacher–teacher interactions, which has important implications for institutions of higher learning

    Orbital and Pauli limiting effects in heavily doped Ba1x_{1-x}Kx_xFe2_2As2_2

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    We investigated the thermodynamic properties of the Fe-based lightly disordered superconductor Ba0.05_{0.05}K0.95_{0.95}Fe2_2As2_2 in external magnetic field H applied along the FeAs layers (H//ab planes). The superconducting (SC) transition temperature for this doping level is Tc_c = 6.6 K. Our analysis of the specific heat C(T,H) measured for T < Tc_c implies a sign change of the superconducting order parameter across different Fermi pockets. We provide experimental evidence for the three components superconducting order parameter. We find that all three components have values which are comparable with the previously reported ones for the stochiometric compound KFe2_2As2_2. Our data for C(T,H) and resistivity rho(T,H) can be interpreted in favor of the dominant orbital contribution to the pair-breaking mechanism at low fields, while Pauli limiting effect dominates at high fields, giving rise to a gapless superconducting state with only the leading non-zero gap.Comment: 7 pages, 5 figure

    Soil Aggregate Response to Three Freeze-Thaw Methods in a Northeastern China Mollisol

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    Freeze-thaw (FT) cycles occur annually in soils of mesic and frigid temperature regimes. FT has profound impacts on soil aggregates yet is often difficult to document in field settings. As a result, laboratory-based FT experiments are widely used, albeit with their own limitations. Both laboratory and field-based research indicates that aggregate properties vary with rates of freezing and thawing as well as the number and amplitudes of FT cycles. In this study, we introduce a continuous freezing-to-thawing-to-freezing technique (i.e., “VTR”) and compare it to a commonly used discrete freeze-then-thaw-then-freeze method (i.e., “RTCR”) and compare both results to natural seasonal changes. Our study soil is the A horizon of the major cropped mollisol in northeastern China. We examined it under natural field soil moisture conditions as well as two controlled soil moisture contents in the laboratory. Both RTCR and VTR show a decrease in large (\u3e1mm) aggregate content and a corresponding increase in medium (0.5 to 0.2 mm) aggregates (P\u3e0.05) that is proportional to the number of FT cycles and soil moisture content. Wet aggregate stability (WAS) increased (P\u3c0.05) over the time of the experiment with each method. RTCR data showed an interaction between FT cycles and soil water content. VTR was better, although certainly not with better matched field results than RTCR, which we attribute its FT cycles being matched to anactual field. These results confirm the dependability and authenticity of the VTR technique

    Phase diagram of CeFeAs1x_{1-x}Px_{x}O obtained from electric resistivity, magnetization, and specific heat measurements

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    We performed a systematic study on the properties of CeFeAs1x_{1-x}Px_{x}O (0x10\leq x\leq 1) by electrical resistivity, magnetization and specific heat measurements. The c-axis lattice constant decreases significantly with increasing P content, suggesting a remarkable chemical pressure. The Fe-3d electrons show the enhanced metallic behavior upon P-doping and undergo a magnetic quantum phase transition around x0.4x \approx 0.4. Meanwhile, the Ce-4f electrons develop a ferromagnetic order near the same doping level. The ferromagnetic order is vanishingly small around x=0.9x=0.9. The data suggest a heavy-fermion-like behavior as x0.95x\geq 0.95. No superconductivity is observed down to 2 K. Our results show the ferromagnetic ordered state as an intermediate phase intruding between the antiferromagnetic bad metal and the nonmagnetic heavy fermion metal and support the cerium-containing iron pnictides as a unique layered Kondo lattice system.Comment: 7 pages, 6 figures, text and figures revised, references added

    Robustness analysis and experimental validation of a fault detection and isolation method for the modular multilevel converter

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    This paper presents a fault detection and isolation (FDI) method for open-circuit faults of power semiconductor devices in a modular multilevel converter (MMC). The proposed FDI method is simple with only one sliding mode observer (SMO) equation and requires no additional transducers. The method is based on an SMO for the circulating current in an MMC. An open-circuit fault of power semiconductor device is detected when the observed circulating current diverges from the measured one. A fault is located by employing an assumption-verification process. To improve the robustness of the proposed FDI method, a new technique based on the observer injection term is introduced to estimate the value of the uncertainties and disturbances, this estimated value can be used to compensate the uncertainties and disturbances. As a result, the proposed FDI scheme can detect and locate an open-circuit fault in a power semiconductor device while ignoring parameter uncertainties, measurement error and other bounded disturbances. The FDI scheme has been implemented in a field programmable gate array (FPGA) using fixed point arithmetic and tested on a single phase MMC prototype. Experimental results under different load conditions show that an open-circuit faulty power semiconductor device in an MMC can be detected and located in less than 50ms
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