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Stiffener requirements for plate girders
Both the static and fatigue behavior of plate girders are influenced by the stiffeners. Girder strength could be substantially increased by the proper use of stiffners. The objective of this thesis is to review the requirements for stiffeners of welded plate girders
Calorimetric and magnetic study for NiMnIn and relative cooling power in paramagnetic inverse magnetocaloric systems
The non-stoichiometric Heusler alloy NiMnIn undergoes a
martensitic phase transformation in the vicinity of 345 K, with the high
temperature austenite phase exhibiting paramagnetic rather than ferromagnetic
behavior, as shown in similar alloys with lower-temperature transformations.
Suitably prepared samples are shown to exhibit a sharp transformation, a
relatively small thermal hysteresis, and a large field-induced entropy change.
We analyzed the magnetocaloric behavior both through magnetization and direct
field-dependent calorimetry measurements. For measurements passing through the
first-order transformation, an improved method for heat-pulse relaxation
calorimetry was designed. The results provide a firm basis for the analytic
evaluation of field-induced entropy changes in related materials. An analysis
of the relative cooling power (RCP), based on the integrated field-induced
entropy change and magnetizing behavior of the Mn spin system with
ferromagnetic correlations, shows that a significant RCP may be obtained in
these materials by tuning the magnetic and structural transformation
temperatures through minor compositional changes or local order changes
The thermal and electrical properties of the promising semiconductor MXene Hf2CO2
In this work, we investigate the thermal and electrical properties of
oxygen-functionalized M2CO2 (M = Ti, Zr, Hf) MXenes using first-principles
calculations. Hf2CO2 is found to exhibit a thermal conductivity better than
MoS2 and phosphorene. The room temperature thermal conductivity along the
armchair direction is determined to be 86.25-131.2 Wm-1K-1 with a flake length
of 5-100 um, and the corresponding value in the zigzag direction is
approximately 42% of that in the armchair direction. Other important thermal
properties of M2CO2 are also considered, including their specific heat and
thermal expansion coefficients. The theoretical room temperature thermal
expansion coefficient of Hf2CO2 is 6.094x10-6 K-1, which is lower than that of
most metals. Moreover, Hf2CO2 is determined to be a semiconductor with a band
gap of 1.657 eV and to have high and anisotropic carrier mobility. At room
temperature, the Hf2CO2 hole mobility in the armchair direction (in the zigzag
direction) is determined to be as high as 13.5x103 cm2V-1s-1 (17.6x103
cm2V-1s-1), which is comparable to that of phosphorene. Broader utilization of
Hf2CO2 as a material for nanoelectronics is likely because of its moderate band
gap, satisfactory thermal conductivity, low thermal expansion coefficient, and
excellent carrier mobility. The corresponding thermal and electrical properties
of Ti2CO2 and Zr2CO2 are also provided here for comparison. Notably, Ti2CO2
presents relatively low thermal conductivity and much higher carrier mobility
than Hf2CO2, which is an indication that Ti2CO2 may be used as an efficient
thermoelectric material.Comment: 26 pages, 5 figures, 2 table
Steel beam-to-column moment connections, February 1973 Presented at ASCE Nat. Struc. Eng\u27g Meeting Preprint 1920, April 1973
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