The phrase "at the upper section" is correct and usable in written English.
It can be used to refer to a specific part or area that is located at the top of something, such as a document, structure, or image.
Example: "The diagram illustrates the components of the machine, with the most critical parts located at the upper section."
Alternatives: "in the top part" or "at the top section".
Reichelt was not clean at the upper section of the 2.1-kilometer (1.3-mile) course, which was set with an unusual amount of short, sharp turns, almost making it look like a giant-slalom course.
In this paper, the characteristic of the radiation fields at the upper section of the reactor of an ADS was analyzed.
The location of the first successful implementations was the Gulf of Mexico, where thick Pleistocene Miocene sediments are represented by clastic rock, which are poorly consolidated at the upper section and are often overpressured from the very top.
In this study, an empirical correlation was developed to predict the solids holdup at the upper section of the riser in circulating and interconnected fluidized beds with an improved level of accuracy for a broad range of operating conditions and riser dimensions.
For the AHPMW waveguide with triangle metal nanowire, the electric field component E y distributes asymmetrically along the Y-axis of the waveguide, and the major E y is confined at the upper section of the triangle metal, which results in the decline of the propagation length.
By increasing cutting density, they tend to precipitate more, and the fluid will no longer be a mixture of mud cutting, i.e., there will be a low-viscosity fluid at the upper section of the drill string, which reduces the stress applied on this section.
Electron microscopy observations indicate that annealing at 250 °C has caused a phase transformation to form Mg5Pd2 at the upper sections of the Mg layer, with the general periodicity of the sample still maintained, in accordance with the reflectometry measurements.
Due to these water management practices and other influencing factors (land use and the construction of dams in the upper section) at catchment scale, it is difficult to assess the risks and consequences of floods without assessing the surrounding mountainous areas (Mezősi, Meyer, et al. 2013); thus this hazard was excluded from the assessment.
The solids were found to flow downward at the U-wall surface in the upper section, where the velocity increased with the superficial gas velocity and the solid suspension density.
But this one is full of delights: the off-center half-timbering on the upper section, the irregular crenelations at the roof, the slight chamfer at the corner.
